50 results on '"Christof Schomerus"'
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2. Body procurement in the Dr. Senckenbergische Anatomie in Frankfurt/Main after the Second World War — From unclaimed corpses to body bequests
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Helmut Wicht, Gisela Hack-Molitor, Christof Schomerus, Leonie Sophie Weiß, and Udo Benzenhöfer
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Human Body ,World War II ,General Medicine ,Detailed data ,language.human_language ,Transitional phase ,German ,Politics ,Body donation ,Procurement ,Germany ,Law ,Political science ,Cadaver ,language ,Humans ,Unclaimed body ,Anatomists ,Anatomy ,Developmental Biology - Abstract
The present paper provides a detailed historical and numerical analysis of the processes regarding body procurement in a particular German anatomical institute, namely, the Dr. Senckenbergische Anatomie (DSA) in Frankfurt am Main. It covers the period from 1946 to 1980; i.e. the transitional phase during which unclaimed corpses were replaced by corpses stemming from body donors. The DSA is fortunate to possess the complete set of records spanning that period. Thus, we cannot only document the (failed) organizational and political efforts of the local anatomists and governmental agencies to uphold the unclaimed body system of old, but we can also present rather detailed data regarding the genesis of the system of body donations. In particular, we will provide evidence that this system was more or less self-generating, and that its emergence was not actively propagated by the local anatomists. Instead, it was triggered by both the media and by the donors themselves, with the latter acting as multipliers. In addition we provide, for the first time, data on the efficacy (in terms of "file corpses" vs. real corpses in anatomy) of a body donation system in Germany.
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- 2021
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3. Robot-assisted percutaneous placement of K-wires during minimally invasive interventions of the spine
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Adam Spandorfer, Yann Croissant, Stephan Zangos, Thomas J. Vogl, U. Joseph Schoepf, Christoph Czerny, Moritz H. Albrecht, Katrin Eichler, and Christof Schomerus
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Computer-assisted surgery ,medicine.medical_specialty ,Robot assistance ,Percutaneous ,Lumbar Vertebrae ,business.industry ,medicine.medical_treatment ,Robotics ,Needle guidance ,Radiation exposure ,03 medical and health sciences ,0302 clinical medicine ,Physical medicine and rehabilitation ,Surgery, Computer-Assisted ,030220 oncology & carcinogenesis ,medicine ,Robot ,Humans ,030211 gastroenterology & hepatology ,Surgery ,business ,Tomography, X-Ray Computed ,Bone Wires - Abstract
Purpose: To assess the accuracy and time requirements of image-guided percutaneous K-wire insertion in the spine using an advanced robot assistance device for needle guidance and to demonst...
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- 2018
4. Recommendations of the working group of the Anatomische Gesellschaft on reduction of formaldehyde exposure in anatomical curricula and institutes
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Johanna Plendl, Janet Weigner, Lars Bräuer, Imke Weyers, Axel Unverzagt, Stefanie Gundlach, Stephan Heermann, Martin Dokter, Daniela Fietz, Birte Steiniger, Daniela Kugelmann, Andreas Schmiedl, Ulrich Fassnacht, Andreas Winkelmann, Magdalena Müller-Gerbl, Tamás Sebestény, Bernhard Hirt, Michael L. Pretterklieber, Christoph Viebahn, Hans-Joachim Schnittler, Ute Nimtschke, Christof Schomerus, Björn Spittau, Merle Winkler, Christoph Redies, Mirko H. H. Schmidt, Ernst Voigt, Jens Waschke, Wolfram F. Neiss, Thomas Tschernig, Erich Brenner, Friedrich Paulsen, Arlette Deutsch, Martin Scaal, Süleyman Ergün, Martin Bergmann, Desalegn Tadesse Egu, and Andreas Buchhorn
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0301 basic medicine ,medicine.medical_specialty ,medicine.medical_treatment ,Veterinary anatomy ,General Medicine ,Body weight ,3. Good health ,03 medical and health sciences ,Dissection ,Body donation ,030104 developmental biology ,Formaldehyde ,Occupational Exposure ,Practice Guidelines as Topic ,medicine ,Respiratory Hypersensitivity ,Humans ,Embalming ,030101 anatomy & morphology ,Occupational exposure limit ,Anatomy ,Intensive care medicine ,Reduction (orthopedic surgery) ,FORMALDEHYDE EXPOSURE ,Developmental Biology - Abstract
The practice of human and veterinary medicine is based on the science of anatomy and dissection courses are still irreplaceable in the teaching of anatomy. Embalming is required to preserve body donors, for which process formaldehyde (FA) is the most frequently used and well characterized biocidal substance. Since January 2016, a new occupational exposure limit (OEL) for FA of 0.37mg/m3 issued by the European Committee on Hazardous Substances is obligatory since FA has been classified as a human 1B carcinogen. The anatomical institutes in the German-speaking region are called upon to consolidate efforts to reduce use of FA in anatomical curricula and body donations. As a result, the Anatomische Gesellschaft (AG) has formed a "Working Group for Reduction of Formaldehyde Exposure in Dissection Courses" tasked with discussion and recommendation of measures to reduce FA. Based on the assessment of the Working Group, the AG has issued an official opinion to the effect that, at this point in time, embalming of body donors without FA completely is not feasible. Therefore, a combination of approaches are to be used to reduce FA exposure, including technical and structural (architectural) adaptations, modification of protocols for fixation and preservation as well as organizational measures. One structural measure considered unavoidable is the integration of air supply and exhaust of individual dissecting tables into the ventilation system of the anatomy building. To embalm human body donors, intra-arterial perfusion fixation with up to 4% FA and a total fluid volume of 150mL/kg body weight will suffice. For animals where body weights and biology of bodies vary widely (i.e. special needs of fixation for ruminants, large animals as horses) perfusion fixation with up to 4% FA and a quantity of fixative solution of 10-15% of the body weight may be required. Preservation of body donors in storage (immersion) can be done with 40% ethanol or in a full bath preservation containing up to 2% FA. Corpse humidification in the dissecting room is possible with 2% phenoxyethanol, in each case without FA. In veterinary anatomy, microbiological burden is often higher and therefore might lead to a need of FA in long-time storage. Compliance with the current OEL in all institutes would appear to be feasible in combination with various organizational measures.
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- 2018
5. Notes on the history of the Dr. Senckenbergische Anatomie in Frankfurt/Main. Part II. The Dr. Senckenbergische Anatomie during the Third Reich and its body supply
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Helmut Wicht, Udo Benzenhöfer, Thomas Theo Brehm, Horst-Werner Korf, and Christof Schomerus
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Hospitals, Psychiatric ,Euthanasia ,business.industry ,Prisoners ,Academies and Institutes ,Biography ,General Medicine ,History, 20th Century ,Germany ,National Socialism ,Law ,Concentration Camps ,Cadaver ,Humans ,Medicine ,War Crimes ,Nazi Germany ,Anatomy ,business ,Order (virtue) ,Communism ,Developmental Biology - Abstract
In order to be able to understand how body supply was maintained at the Dr. Senckenbergische Anatomie from 1933 to 1945 – with special emphasis on victims of the National Socialist regime – we have collected information from various and often fragmentary sources. The documents reveal that during this period at least 474 bodies were brought to the anatomical institute. Among them were the bodies of at least 71 prisoners, 51 of whom had been executed, and the bodies of 8 inmates of (labor-) camps. 356 unclaimed bodies were received, some of them may stem from victims of “euthanasia” programs. The sources of 39, as of yet, unnamed bodies could not be verified. The current collections and the catalogs were screened for remains of victims of the National Socialist regime, but none were found. The vast majority of the bodies were used for teaching purposes. Hans Schreiber, one of the directors of the institute, whose biography is provided here, used at least 9 additional executed individuals for his research. Wherever possible, we have identified the victims of the National Socialist regime, executed persons and the inmates of (labor-) camps, whose bodies were used by the anatomists in Frankfurt, by name. Among the victims was Georg Froba, a communist philanthropist, whose biography is provided.
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- 2015
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6. Of pigs and men-comparing the development of Calliphora vicina (Diptera: Calliphoridae) on human and porcine tissue
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Marcel A. Verhoff, Jens Amendt, Christof Schomerus, and Victoria Bernhardt
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Veterinary medicine ,Pathology ,medicine.medical_specialty ,Calliphora vicina ,Swine ,030231 tropical medicine ,Loin ,Pathology and Forensic Medicine ,03 medical and health sciences ,0302 clinical medicine ,Porcine tissue ,parasitic diseases ,medicine ,Juvenile ,Animals ,Humans ,030216 legal & forensic medicine ,Forensic entomology ,Calliphoridae ,Larva ,biology ,Diptera ,fungi ,Forensic Sciences ,technology, industry, and agriculture ,food and beverages ,Feeding Behavior ,biology.organism_classification ,Body Remains ,Pupa ,Postmortem Changes ,Entomology - Abstract
Over the last decades, studies on juvenile development of forensically important Diptera were performed by using non-human tissues (e.g., beef liver) as a nutrition medium. Such developmental data are used as a reference in determining the age of juvenile necrophagous insects sampled from a human body and thereby to estimate the minimum postmortem interval (PMImin). Despite the acceptance of these studies in the forensic community, some might ask whether such data appropriately reflect the growth of blow flies on human tissue. We, therefore, studied larval growth rates and development times of Calliphora vicina (Diptera: Calliphoridae) on human muscle tissue as well as on pork loin, pork liver, and minced pork at 25 °C. Larval growth rates were significantly (p
- Published
- 2016
7. Novel, Portable, Cassette-Sized, and Wireless Flat-Panel Digital Radiography System: Initial Workflow Results Versus Computed Radiography
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Volkmar Jacobi, Thomas J. Vogl, Nagy N.N. Naguib, Thomas Lehnert, Christof Schomerus, Joern O. Balzer, and Hanns Ackermann
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Adult ,Male ,Adolescent ,Radiography ,Patient positioning ,Efficiency, Organizational ,Flat panel ,Patient Positioning ,Software ,Humans ,Wireless ,Medicine ,X-Ray Intensifying Screens ,Radiology, Nuclear Medicine and imaging ,Computed radiography ,Child ,Aged ,Digital radiography ,Aged, 80 and over ,business.industry ,Equipment Design ,General Medicine ,Middle Aged ,Radiographic Image Enhancement ,Workflow ,Time and Motion Studies ,Radiographic Image Interpretation, Computer-Assisted ,Female ,business ,Nuclear medicine ,Computer hardware - Abstract
The purpose of this article is to compare workflow efficiency between a conventional computed radiography (CR) system and a novel, portable, cassette-sized, and wireless flat-panel digital radiography (DR) system.Observational time-motion analyses were performed at one site at which CR and the new portable DR system are used concurrently. The workflow steps of both systems were identified and categorized to facilitate comparison. The times required for examination preparation, patient positioning, exposure, postacquisition processing, and the examination as a whole were recorded by a neutral observer. Timing differences between the CR and portable DR systems were compared, and all data were analyzed using commercially available statistical software. Nine general radiographic examination types were selected, with approximately 50 patients per examination type.A total of 941 examinations (CR, n = 474; portable DR, n = 467) were timed in this study. Total examination time differences between CR and portable DR system (mean, 26.44 seconds; median 26.99 seconds) were found to be statistically significant (p0.001), with DR proving faster than CR. The single largest contributor to the time difference between CR and portable DR was postacquisition processing (mean, 26.58 seconds; median, 25.91 seconds), which was a composite of multiple individual steps, including cassette transport (CR only, mean, 13.22 seconds; median, 12.74 seconds), cassette readout (mean, 10.15 seconds; median, 10.4 seconds), and postprocessing (mean, 3.21 seconds; median, 3.11 seconds).Overall radiographer time was significantly shorter when performing examination-related tasks with the novel, portable DR system than when performing comparable tasks with the CR system, a difference that appears to result largely from technology configuration.
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- 2011
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8. Spatial and temporal expression patterns ofBmaldelineate a circadian clock in the nervous system ofBranchiostoma lanceolatum
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Elke Laedtke, Horst-Werner Korf, Christof Schomerus, and Helmut Wicht
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animal structures ,Lancelet ,Molecular Sequence Data ,Circadian clock ,Nervous System ,Prosencephalon ,Biological Clocks ,Chordata, Nonvertebrate ,Animals ,Humans ,Amino Acid Sequence ,Cloning, Molecular ,Phylogeny ,Genetics ,Cephalochordate ,Regulation of gene expression ,Branchiostoma lanceolatum ,Base Sequence ,biology ,Suprachiasmatic nucleus ,General Neuroscience ,ARNTL Transcription Factors ,biology.organism_classification ,Biological Evolution ,Circadian Rhythm ,Cell biology ,ARNTL ,CLOCK ,Gene Expression Regulation ,Suprachiasmatic Nucleus - Abstract
We cloned the homologue of the clock gene Bmal from a cephalochordate, Branchiostoma lanceolatum (syn. amphioxus). Amphioxus possesses a single copy of this gene (amphiBmal) that encodes for a protein of 649 amino acids, which is quite similar to BMALs of other chordates. The gene is expressed by a restricted cell group in the anterior vesicle of the neural tube, and its expression site coincides with that of another clock gene, namely, amphiPer. The expression of amphiBmal shows a rhythmic fluctuation that persists under constant darkness and is, thus, circadian. Similar to the situation in craniates, the peak phases of the amphiBmal and amphiPer expression are offset by 12 hours. Based on these observations and the putative homology between the diencephalon of vertebrates and the anterior vesicle of lancelets, we suggest a homology between the suprachiasmatic nucleus of craniates and the amphiBmal/amphiPer-expressing cell group of amphioxus.
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- 2010
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9. 'Isolierte Verletzung' der Ligamenta alaria
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K.-D. Thomann, M. Rauschmann, T. Sebestény, and Christof Schomerus
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Gynecology ,medicine.medical_specialty ,Whiplash injury ,business.industry ,medicine ,Orthopedics and Sports Medicine ,Ligamenta alaria ,business - Abstract
Distorsionen der Halswirbelsaule nach Auffahrunfallen spielen im Rahmen der Begutachtung eine grose Rolle. Besondere Schwierigkeiten bereiten prolongierte oder chronische Verlaufe. Der Radiologe E. Volle entwickelte und publizierte ein Klassifikationssystem isolierter Verletzungen der Ligamenta alaria. Bei einer grosen Anzahl von Patienten wurde daraufhin der kraniozervikale Ubergang operiert. Die Ergebnisse wurden mehrfach veroffentlicht. Die vorliegende Publikation beschreibt die Anatomie der Ligamenta alaria, Komplexverletzungen, das Konzept der isolierten Lasion der Ligamenta alaria und die operative Behandlung. Ausgewertet werden deutsche und internationale Veroffentlichungen. Ergebnis: Isolierte Verletzungen der Ligamenta alaria konnten nicht nachgewiesen werden. Die publizierten Befunde beruhen nach aktuellem Kenntnisstand auf einer Fehlinterpretation kernspintomographischer Befunde – sie sind als Artefakte anzusehen. Der Klassifikation isolierter Verletzungen der Ligamenta alaria liegt kein anatomisches Korrelat zugrunde. Eine operative Stabilisation aufgrund einer angeblich isolierten Verletzung der Ligamenta alaria ist somit nicht indiziert. Diese Aussage trifft nicht fur stattgehabte Verletzungen zu, die im Rahmen von Hochrasanztraumata aufgetreten sind, mit einem komplexen Verletzungsmuster einhergehen und andere Strukturen (Gelenkkapseln, Membrana atlantooccipitalis) miteinbeziehen.
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- 2010
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10. Nocturnal Behavior and RhythmicPeriodGene Expression in a Lancelet,Branchiostoma lanceolatum
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Elke Laedtke, Horst-Werner Korf, Frédéric Moret, Helmut Wicht, Qian Zhang, and Christof Schomerus
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Male ,Physiology ,Lancelet ,Photoperiod ,Period (gene) ,Circadian clock ,Biological Clocks ,Chordata, Nonvertebrate ,Physiology (medical) ,Animals ,Circadian rhythm ,Phylogeny ,Regulation of gene expression ,Behavior ,Branchiostoma lanceolatum ,biology ,Suprachiasmatic nucleus ,Nuclear Proteins ,Anatomy ,Darkness ,biology.organism_classification ,Circadian Rhythm ,Cell biology ,CLOCK ,Gene Expression Regulation ,Female - Abstract
The authors here present the first anatomical, molecular biological, and ethological data on the organization of the circadian system of a lancelet, Branchiostoma lanceolatum, a close invertebrate relative of vertebrates. B. lanceolatum was found to be a nocturnal animal and, since its rhythmic activity persisted under constant darkness, it also appears to possess an endogenous, circadian oscillator. The authors cloned a homolog of the clock gene Period ( Per), which plays a central (inhibitory) role in the biochemical machinery of the circadian oscillators of both vertebrates and protostomians. This gene from B. lanceolatum was designated as amphiPer. Both the sequence of its cDNA and that of the predicted protein are more similar to those of the Per paralogs of vertebrates than to those of the single protostomian Per gene. A strong expression of amphiPer was found in a small cell group in the anterior neural tube. The amphiPer mRNA levels fluctuated in a rhythmic manner, being high early in the day and low late at night. The authors' data suggest a homology of the amphiPer expessing cells to the suprachiasmatic nucleus of vertebrates.
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- 2008
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11. Cannabinoids attenuate norepinephrine-induced melatonin biosynthesis in the rat pineal gland by reducing arylalkylamine N-acetyltransferase activity without involvement of cannabinoid receptors
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Iris Habazettl, Marco Koch, Faramarz Dehghani, Horst-Werner Korf, and Christof Schomerus
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Male ,endocrine system ,medicine.medical_specialty ,Cannabinoid receptor ,AANAT ,medicine.medical_treatment ,Biology ,Pharmacology ,Arylalkylamine N-Acetyltransferase ,Pineal Gland ,Biochemistry ,Melatonin ,Norepinephrine ,Cellular and Molecular Neuroscience ,Pineal gland ,Organ Culture Techniques ,Internal medicine ,Cyclic AMP ,medicine ,Animals ,Drug Interactions ,Enzyme Inhibitors ,Rats, Wistar ,Cyclic AMP Response Element-Binding Protein ,Radiometry ,Receptors, Cannabinoid ,Cells, Cultured ,Dose-Response Relationship, Drug ,Cannabinoids ,Immunohistochemistry ,Endocannabinoid system ,Rats ,Enzyme Activation ,Endocrinology ,medicine.anatomical_structure ,Area Under Curve ,Arylalkylamine ,lipids (amino acids, peptides, and proteins) ,Cannabinoid ,Signal transduction ,hormones, hormone substitutes, and hormone antagonists ,medicine.drug - Abstract
Cannabinoids modulate neuronal and neuroendocrine circuits by binding to cannabinoid receptors acting upon cAMP/Ca(2+)-mediated intracellular signaling cascades. The rat pineal represents an established model to investigate intracellular signaling processes because a well defined input, the neurotransmitter norepinephrine, is transformed via cAMP/Ca(2+)-dependent mechanisms into an easily detectable output signal, the biosynthesis of melatonin. Here we investigated the impact of cannabinoids on norepinephrine-regulated melatonin biosynthesis in the rat pineal. We demonstrated that treatment of cultured rat pineals with 9-carboxy-11-nor-delta-9-tetrahydrocannabinol (THC), cannabidiol or cannabinol significantly reduced norepinephrine-induced arylalkylamine N-acetyltransferase (AANAT) activity and melatonin biosynthesis. These effects were not mimicked by the cannabinoid receptor agonist WIN55,212-2 and were not blocked by cannabinoid 1 and 2 receptor antagonists. The cannabinoids used did not affect norepinephrine-induced increases in cAMP/Ca(2+) levels. Notably, cannabinoids were found to directly inhibit AANAT activity in lysates of the pineal gland. This effect was specific in so far as cannabinoids did not influence the activity of hydroxyindole-O-methyltransferase (HIOMT), the last enzyme in melatonin biosynthesis. Taken together, our data strongly suggest that cannabinoids inhibit AANAT activity and attenuate melatonin biosynthesis through intracellular actions without involvement of classical cannabinoid receptor-dependent signaling cascades.
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- 2006
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12. Extracellular nucleotide signaling in adult neural stem cells: synergism with growth factor-mediated cellular proliferation
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Marc Füllgrabe, Santosh K. Mishra, Horst-Werner Korf, Simon C. Robson, Varsha Shukla, H. Zimmermann, Christof Schomerus, Yukio Ikehara, Norbert Braun, Jean Sévigny, and Christian Gachet
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Adenosine ,medicine.medical_treatment ,Subventricular zone ,Uridine Triphosphate ,Biology ,Receptors, Purinergic P2Y2 ,Mice ,Receptors, Purinergic P2Y1 ,Adenosine Triphosphate ,Neurosphere ,Purinergic P2 Receptor Antagonists ,medicine ,Extracellular ,Animals ,Progenitor cell ,Molecular Biology ,Cells, Cultured ,Cell Proliferation ,Adenosine Triphosphatases ,Mice, Knockout ,Neurons ,Epidermal Growth Factor ,Receptors, Purinergic P2 ,Multipotent Stem Cells ,Growth factor ,Neurogenesis ,Alkaline Phosphatase ,Molecular biology ,Neural stem cell ,Adenosine Diphosphate ,Isoenzymes ,Mice, Inbred C57BL ,medicine.anatomical_structure ,Calcium ,Fibroblast Growth Factor 2 ,Signal Transduction ,Developmental Biology ,Adult stem cell - Abstract
We have previously shown that the extracellular nucleoside triphosphate-hydrolyzing enzyme NTPDase2 is highly expressed in situ by stem/progenitor cells of the two neurogenic regions of the adult murine brain:the subventricular zone (type B cells) and the dentate gyrus of the hippocampus (residual radial glia). We explored the possibility that adult multipotent neural stem cells express nucleotide receptors and investigated their functional properties in vitro. Neurospheres cultured from the adult mouse SVZ in the presence of epidermal growth factor and fibroblast growth factor 2 expressed the ecto-nucleotidases NTPDase2 and the tissue non-specific isoform of alkaline phosphatase, hydrolyzing extracellular ATP to adenosine. ATP, ADP and, to a lesser extent, UTP evoked rapid Ca2+ transients in neurospheres that were exclusively mediated by the metabotropic P2Y1 and P2Y2 nucleotide receptors. In addition,agonists of these receptors and low concentrations of adenosine augmented cell proliferation in the presence of growth factors. Neurosphere cell proliferation was attenuated after application of the P2Y1-receptor antagonist MRS2179 and in neurospheres from P2Y1-receptor knockout mice. In situ hybridization identified P2Y1-receptor mRNA in clusters of SVZ cells. Our results infer nucleotide receptor-mediated synergism that augments growth factor-mediated cell proliferation. Together with the in situ data, this supports the notion that extracellular nucleotides contribute to the control of adult neurogenesis.
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- 2006
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13. Mechanisms Regulating Melatonin Synthesis in the Mammalian Pineal Organ
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Horst-Werner Korf and Christof Schomerus
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medicine.medical_specialty ,Light ,Transcription, Genetic ,AANAT ,CREB ,Arylalkylamine N-Acetyltransferase ,Pineal Gland ,General Biochemistry, Genetics and Molecular Biology ,Pinealocyte ,Melatonin ,Pineal gland ,History and Philosophy of Science ,Internal medicine ,medicine ,Animals ,Protein kinase A ,Protein kinase C ,biology ,General Neuroscience ,Circadian Rhythm ,Rats ,Endocrinology ,medicine.anatomical_structure ,biology.protein ,Phosphorylation ,Cattle ,medicine.drug - Abstract
The day/night rhythm in melatonin production is a characteristic feature in vertebrate physiology. This hormonal signal reliably reflects the environmental light conditions and is independent of behavioral aspects. In all mammalian species, melatonin production is regulated by norepinephrine, which is released from sympathetic nerve fibers exclusively at night. Norepinephrine elevates the intracellular cAMP concentration via beta-adrenergic receptors and activates the cAMP-dependent protein kinase A. This pathway is crucial for regulation of the penultimate enzyme in melatonin biosynthesis, the arylalkylamine N-acetyltransferase (AANAT); cAMP/protein kinase A may, however, act in different ways. In ungulates and primates, pinealocytes constantly synthesize AANAT protein from continually available Aanat mRNA. During the day-in the absence of noradrenergic stimulation-the protein is immediately destroyed by proteasomal proteolysis. At nighttime, elevated cAMP levels cause phosphorylation of AANAT by protein kinase A. This posttranslational modification leads to interaction of phosphorylated AANAT with regulatory 14-3-3 proteins, which protect AANAT from degradation. Increases in AANAT protein are paralleled by increases in enzyme activity. Stimulation of the cAMP/protein kinase A pathway may also activate pineal gene expression. In rodents, transcriptional activation of the Aanat gene is the primary mechanism for the induction of melatonin biosynthesis and results in marked day/night fluctuations in Aanat mRNA. It involves protein kinase A-dependent phosphorylation of the transcription factor cyclic AMP response element-binding protein (CREB) and binding of phosphorylated CREB in the promoter region of the Aanat gene. In conclusion, a common neuroendocrine principle, the nocturnal rise in melatonin, is controlled by strikingly diverse regulatory mechanisms. This diversity has emerged in the course of evolution and reflects the high adaptive plasticity of the melatonin-generating pineal organ.
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- 2005
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14. Activation of Arylalkylamine N-Acetyltransferase by Phorbol Esters in Bovine Pinealocytes Suggests a Novel Regulatory Pathway in Melatonin Synthesis
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Elke Laedtke, Christof Schomerus, and Horst-Werner Korf
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Male ,medicine.medical_specialty ,AANAT ,Endocrinology, Diabetes and Metabolism ,Biology ,Arylalkylamine N-Acetyltransferase ,Pineal Gland ,Pinealocyte ,Melatonin ,Cellular and Molecular Neuroscience ,Pineal gland ,chemistry.chemical_compound ,Organ Culture Techniques ,Endocrinology ,Internal medicine ,Phorbol Esters ,Cyclic AMP ,medicine ,Animals ,Calcium Signaling ,Protein kinase A ,Phorbol 12,13-Dibutyrate ,Protein Kinase C ,Protein kinase C ,Endocrine and Autonomic Systems ,Enzyme Activation ,medicine.anatomical_structure ,chemistry ,Arylalkylamine ,Phorbol ,Tetradecanoylphorbol Acetate ,Cattle ,Female ,Signal Transduction ,medicine.drug - Abstract
In all mammalian species investigated, noradrenaline activates a beta-adrenoceptor/cAMP/protein kinase A-dependent mechanism to switch on arylalkylamine N-acetyltransferase and melatonin biosynthesis in the pineal gland. Other compounds which are known to influence the melatonin-generating system are phorbol esters. The effect of phorbol esters on regulation of melatonin synthesis has been mainly investigated in rat pinealocytes. In these cells, phorbol esters do not increase cAMP levels and arylalkylamine N-acetyltransferase on their own; however, phorbol esters potentiate the effects on cAMP and AANAT activity induced upon beta-adrenoceptor stimulation. In the present study, we investigated the effect of phorbol esters on the regulation of melatonin synthesis in bovine pinealocytes. We show that, in these cells, the phorbol esters 4beta-phorbol 12-myristate 13-acetate (PMA) or phorbol 12,13-dibutyrate have a direct stimulatory effect and induced 4-10-fold increases in AANAT protein levels, AANAT activity and melatonin production. The extent of these effects was similar to those induced by noradrenaline. Notably, responses to PMA were not accompanied by increases in cAMP levels. Northern blot analysis showed that Aanat mRNA levels did not change upon PMA treatment indicating that phorbol esters control AANAT at a post-transcriptional level. The effects on AANAT and melatonin production were reduced by use of protein kinase C inhibitors, but not by blockade of the cyclic AMP/protein kinase A pathway. Our results point towards a novel mechanism in the regulation of melatonin production that is cAMP-independent and involves protein kinase C. The study is of particular interest because regulation of melatonin biosynthesis in bovines may resemble that in primates more closely than that in rodents.
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- 2004
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15. Dephosphorylation of pCREB by protein serine/threonine phosphatases is involved in inactivation of Aanat gene transcription in rat pineal gland
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Horst-Werner Korf, Viviane Mauhin, Jörg H. Stehle, Marco Koch, and Christof Schomerus
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Dephosphorylation ,Cellular and Molecular Neuroscience ,Downregulation and upregulation ,AANAT ,Gene expression ,Arylalkylamine ,Biology ,Biochemistry ,Molecular biology ,Transcription factor ,Pinealocyte ,Endocrine gland - Abstract
The rat pineal gland is a suitable model to investigate neurotransmitter-controlled gene expression, because it is well established that the stimulation of melatonin biosynthesis by norepinephrine (NE) depends on the activation of the gene that encodes arylalkylamine N-acetyltransferase (AANAT), the melatonin rhythm enzyme. The mechanisms responsible for downregulation of Aanat transcription are less clear. In this in vitro study we investigated the role of pCREB dephosphorylation for termination of Aanat gene transcription. Immunosignals for pCREB, strongly induced after NE stimulation, rapidly decreased after withdrawal of NE. The immunoreactivity of the inhibitory transcription factor ICER increased twofold after NE treatment for 6 h, but did not change within 30 min after removal of the stimulus. Application of protein serine/threonine phosphatase (PSP) inhibitors prevented pCREB dephosphorylation and blocked the decreases in Aanat mRNA levels, AANAT protein amount and melatonin biosynthesis all of which occurred rapidly after NE withdrawal. PSPs in the rat pineal gland were characterized by immunocytochemistry and immunoblotting. NE-stimulation for 8 h induced accumulation of PSP1-catalytic subunit (CSU) in pinealocyte nuclei, but did not affect the distribution of PSP2A-CSU. The results identify dephosphorylation of pCREB by PSPs as an essential mechanism for downregulation of Aanat transcription in the rat pineal gland.
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- 2003
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16. Norepinephrine-dependent phosphorylation of the transcription factor cyclic adenosine monophosphate responsive element-binding protein in bovine pinealocytes
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Elke Laedtke, Christof Schomerus, and Horst-Werner Korf
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biology ,AANAT ,CREB ,Molecular biology ,Pinealocyte ,Pineal gland ,chemistry.chemical_compound ,Endocrinology ,medicine.anatomical_structure ,chemistry ,Arylalkylamine ,medicine ,biology.protein ,Cyclic adenosine monophosphate ,CREB1 ,Transcription factor - Abstract
Inthemammalian pineal gland,norepinephrine (NE)isreleasedduringthenightfromsympatheticnerveendings[1]in response to neuronal signals from the endogenousoscillator,thehypothalamicnucleussuprachiasmaticus[2].NEdrivesthesynthesisofthepinealhormonemelatoninwhich,uponitssynthesis,isimmediatelyreleasedintothecirculation. The role of NE as the dominant regulator(input)andtheday/nightrhythminmelatoninproduction(output) represent highly conserved features in pinealphysiologyofallmammalsinvestigatedsofar.Instrikingcontrast, the molecular mechanisms that translate thenorepinephrinergic input into the melatonin signal varyamongpinealocytesfromdifferentmammalianspecies[3–5].In the rat, and apparently also in other rodents,melatonin synthesis is primarily regulated through tran-scriptionalmechanisms.NEactivatespinealocytesthroughtheb-adrenergic/cyclicadenosinemonophosphate(cAMP)pathway[3,4,6].ElevatedcAMPlevelsresultinactivationofproteinkinaseAwhichphosphorylatesthetranscriptionfactor cAMP response element-binding protein (CREB)[7–9]. Phosphorylated CREB (pCREB) binds to cAMPresponse elements (CREs) in the promoter regions ofvariousgenes.Intheratpinealorgan,pCREBisofcentralimportanceforinitiation,maintenance,andterminationoftherhythmicmelatoninbiosynthesis[10].Onecrucialtargetof pCREB is the gene for the arylalkylamine N-acetyl-transferase(AANAT),thepenultimateandkeyenzymeofmelatoninsynthesis.IncreasesinAanatmRNAlevelsarecloselyassociatedwithsimilarchangesinAANATproteinlevelsandAANATactivity[3,6].OthertargetsofpCREBare thegenes for theb-adrenergicreceptor [11] and forthe transcription factor inducible cAMP early repressorAbstract: Norepinephrine(NE)-dependentactivationoftranscriptionfactorsisofcentralimportancefortherhythmicproductionofmelatoninintherodentpinealgland.Atvariancewithrodents,NEregulatesmelatoninbiosynthesisthroughpost-translationalmechanismsinungulates,anditisnotyetknownwhethertranscriptionfactorsplayanyroleinungulatepinealfunctions.Here,weinvestigatedinisolatedbovinepinealocytestheNE-dependentphosphorylationofthetranscriptionfactorcyclicadenosinemonophosphate(cAMP)responsiveelement-bindingprotein(CREB)andcomparedtheeffectsofNEwiththoseofvasoactiveintestinalpeptide(VIP)andpituitaryadenylatecyclase-activatingpolypeptide(PACAP).Treatmentwith10
- Published
- 2003
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17. Notes on the history of the Dr. Senckenbergische Anatomie in Frankfurt/Main. Part I. Development of student numbers, body procurement, and gross anatomy courses from 1914 to 2013
- Author
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Thomas Theo Brehm, Horst-Werner Korf, Udo Benzenhöfer, Christof Schomerus, and Helmut Wicht
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Student population ,Students, Medical ,business.industry ,Library science ,General Medicine ,History, 20th Century ,Procurement ,Student affairs ,National Socialism ,Cadaver ,Gross anatomy ,Medicine ,Humans ,Nazi Germany ,Curriculum ,Anatomy ,business ,Developmental Biology - Abstract
Until recently, it was believed that all internal documentation regarding student affairs and body procurement of the Dr. Senckenbergische Anatomie concerning the time before March 1944 - when the building was destroyed during an Allied air raid - was lost. A few years ago, however, we discovered stacks of old documents in the current anatomy building. These documents permitted a reconstruction (1) of the history of body procurement, student numbers and course management from 1914 to 1944, as well as (2) some aspects of the building's history in the time immediately after its destruction that have hitherto not been documented. In this paper (Part I), we will deal with the organizational history of the Dr. Senckenbergische Anatomie from 1914 to 2013, placing special emphasis on the development of the student population and body procurement, as well as on the major changes that occurred in the gross anatomy labs of the last century. More than 30,000 students were trained in the Dr. Senckenbergische Anatomie over the last 100 years, and more than 3000 bodies have been received. The number of incoming bodies has remained quite stable in all these years and is, on average, approximately 32 per year. The number of students entering the gross anatomy lab during that period, however, rose from less than 100 to more than 600. A companion paper (Part II) deals with the years of the Third Reich (1933-1945) in more detail.
- Published
- 2015
18. Signal transduction and regulation of melatonin synthesis in bovine pinealocytes: impact of adrenergic, peptidergic and cholinergic stimuli
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James Olcese, Joan L. Weller, Christof Schomerus, Elke Laedtke, David C. Klein, and Horst-Werner Korf
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endocrine system ,medicine.medical_specialty ,Histology ,Arylamine N-Acetyltransferase ,AANAT ,Stimulation ,Biology ,Pineal Gland ,Pathology and Forensic Medicine ,Pinealocyte ,Melatonin ,Norepinephrine ,Phenylephrine ,1-Methyl-3-isobutylxanthine ,Internal medicine ,Muscarinic acetylcholine receptor ,Cyclic AMP ,medicine ,Animals ,Calcium Signaling ,Receptor ,Neuropeptides ,Cell Biology ,Immunohistochemistry ,Nicotinic agonist ,Endocrinology ,Pituitary Adenylate Cyclase-Activating Polypeptide ,Cattle ,Signal transduction ,hormones, hormone substitutes, and hormone antagonists ,Signal Transduction ,Vasoactive Intestinal Peptide ,medicine.drug - Abstract
Limited studies of the regulation of pineal melatonin biosynthesis in ungulates indicate that it differs considerably from that in rodents. Here we have investigated several signal transduction cascades and their impact on melatonin synthesis in bovine pinealocytes. Norepinephrine increased the intracellular calcium ion concentration ([Ca2+]i) via alpha(1)-adrenergic receptors. Activation of beta-adrenergic receptors enhanced cAMP accumulation and rapidly elevated arylalkylamine N-acetyltransferase (AANAT) activity and melatonin secretion. The beta-adrenergically evoked increases in AANAT activity were potentiated by alpha(1)-adrenergic stimulation, but this was not seen with cAMP or melatonin production. PACAP treatment caused small increases in cAMP, AANAT activity and melatonin biosynthesis, apparently in a subpopulation of cells. VIP and glutamate did not influence any of these parameters. Activation of nicotinic and muscarinic acetylcholine receptors increased [Ca2+]i, but did not alter cAMP levels, AANAT activity or melatonin production. Our study reveals that discrete differences in pineal signal transduction exist between the cow and rodent, and emphasizes the potential importance that the analysis of ungulate pinealocytes may play in understanding regulation of pineal melatonin biosynthesis in primates and man, whose melatonin-generating system appears to be more similar to that in ungulates than to that in rodents.
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- 2002
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19. Selective Adrenergic/Cyclic AMP-Dependent Switch-Off of Proteasomal Proteolysis Alone Switches on Neural Signal Transduction
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Elke Laedtke, Horst-Werner Korf, David C. Klein, Joan L. Weller, and Christof Schomerus
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Male ,Proteasome Endopeptidase Complex ,Arylamine N-Acetyltransferase ,AANAT ,Proteolysis ,Biology ,Pineal Gland ,Biochemistry ,Pinealocyte ,Norepinephrine ,Cellular and Molecular Neuroscience ,Pineal gland ,Multienzyme Complexes ,Cyclic AMP ,medicine ,Animals ,Protease Inhibitors ,RNA, Messenger ,Cells, Cultured ,Neurons ,Protein Synthesis Inhibitors ,Messenger RNA ,medicine.diagnostic_test ,Colforsin ,Aralkylamine N-acetyltransferase ,Stimulation, Chemical ,Acetylcysteine ,Cysteine Endopeptidases ,medicine.anatomical_structure ,Bucladesine ,Arylalkylamine ,Cattle ,Female ,Puromycin ,Signal transduction ,Peptide Hydrolases ,Signal Transduction - Abstract
The molecular processes underlying neural transmission are central issues in neurobiology. Here we describe a novel mechanism through which noradrenaline (NA) activates its target cells, using the mammalian pineal organ as a model. In this neuroendocrine transducer, NA stimulates arylalkylamine N-acetyltransferase (AANAT; EC 2.3.1.87), the key enzyme regulating the nocturnal melatonin production. In rodents, AANAT protein accumulates as a result of enhanced transcription, but in primates and ungulates, the AANAT mRNA level fluctuates only marginally, indicating that other mechanisms regulate AANAT protein and activity. These were investigated in cultured bovine pinealocytes. AANAT mRNA was readily detectable in unstimulated pinealocytes, and levels did not change following NA treatment. In contrast, NA increased AANAT protein levels in parallel with AANAT activity, apparently through a cyclic AMP-mediated mechanism. Immunocytochemistry revealed that the changes in AANAT protein levels occurred in virtually all pinealocytes. Inhibition of AANAT degradation by proteasomal proteolysis alone was found to switch-on enzyme activity by increasing AANAT protein levels five- to 10-fold. Accordingly, under unstimulated conditions AANAT protein is continually synthesized and immediately destroyed by proteasomal proteolysis. NA appears to act via cyclic AMP to protect AANAT from proteolytic destruction, resulting in accumulation of the protein. These findings show that tightly regulated control of proteasomal proteolysis of a specific protein alone can play a pivotal role in neural regulation.
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- 2002
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20. Effects of neuroactive substances on the activity of subcommissural organ cells in dispersed cell and explant cultures
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Frank Nürnberger, Mda Kopp, E. M. Rodríguez, Faramarz Dehghani, Christof Schomerus, Annie Meiniel, Horst-W. Korf, S. Schöniger, and Erik Maronde
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Male ,Serotonin ,medicine.medical_specialty ,Histology ,chemistry.chemical_element ,Substance P ,Biology ,Calcium ,Calcium in biology ,Pathology and Forensic Medicine ,Adenosine Triphosphate ,Calcium imaging ,Culture Techniques ,Internal medicine ,medicine ,Extracellular ,Animals ,Calcium Signaling ,Cells, Cultured ,Receptors, Tachykinin ,Neurotransmitter Agents ,Dose-Response Relationship, Drug ,Voltage-dependent calcium channel ,Colforsin ,T-type calcium channel ,Cell Biology ,Immunohistochemistry ,Cell biology ,Calcium ATPase ,Endocrinology ,chemistry ,Cattle ,Female ,Subcommissural Organ ,Subcommissural organ - Abstract
The subcommissural organ (SCO), an ependymal (glial) circumventricular organ, releases glycoproteins into the cerebrospinal fluid; however, the regulation of its secretory activity is largely unknown. To identify neuroactive substances that may regulate SCO activity, we investigated immunocytochemically identified bovine SCO cells by means of calcium imaging. This analysis was focused on: (1) serotonin (5HT) and substance P (SP), immunocytochemically shown to be present in axons innervating the bovine SCO; and (2) ATP, known to activate glial cells. 5HT had no effect on the intracellular calcium concentration ([Ca(2+)](i)), and its precise role remains to be clarified. SP elicited rises in [Ca(2+)](i) in approx. 30% and ATP in even 85% of the analyzed SCO cells. These effects were dose-dependent, involved NK(3) and P2Y(2) receptors linked to G protein and phospholipase C (PLC) activation, and could not be mimicked by forskolin or 8-bromo-cAMP. In 50% of the SP-sensitive cells, the increases in [Ca(2+)](i) comprised calcium release from thapsigargin-sensitive intracellular stores and an influx of extracellular calcium via protein kinase C (PKC)-induced opening of L-type voltage-gated calcium channels (VGCCs). In the remaining SP-sensitive cells, the increase in [Ca(2+)](i) was caused exclusively by influx of extracellular calcium via VGCCs of the L-type. In all ATP-sensitive cells the increase in [Ca(2+)](i) involved calcium release from thapsigargin-sensitive intracellular stores and a PKC-mediated influx of extracellular calcium via L-type VGCCs. Our data suggest that SP and ATP are involved in regulation of the activity of SCO cells.
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- 2002
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21. Transcription factor dynamics and neuroendocrine signalling in the mouse pineal gland: a comparative analysis of melatonin-deficient C57BL mice and melatonin-proficient C3H mice
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Charlotte von Gall, Alfred J. Lewy, Horst-Werner Korf, Paul Pévet, Christof Schomerus, Berthe Vivien-Roels, and Jörg H. Stehle
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endocrine system ,CAMP-Responsive Element Modulator ,education.field_of_study ,medicine.medical_specialty ,biology ,AANAT ,General Neuroscience ,CREB ,Pinealocyte ,Melatonin ,Pineal gland ,medicine.anatomical_structure ,Endocrinology ,Internal medicine ,Arylalkylamine ,medicine ,biology.protein ,Transcriptional regulation ,education ,hormones, hormone substitutes, and hormone antagonists ,medicine.drug - Abstract
In rodents, the nocturnal rise and fall of arylalkylamine N-acetyltransferase (AANAT) activity controls the rhythmic synthesis of melatonin, the hormone of the pineal gland. This rhythm involves the transcriptional regulation of the AANAT by two norepinephrine (NE)-inducible transcription factors, e.g. the activator pCREB (phosphorylated Ca2+/cAMP-response element binding protein) and the inhibitor ICER (inducible cAMP early repressor). Most inbred mouse strains do not produce melatonin under standard laboratory light/dark conditions. As melatonin-deficient mice are often the founders for transgenic animals used for chronobiological experimentations, molecular components of neuroendocrine signalling in the pineal gland as an integral part of clock entrainment mechanisms have to be deciphered. We therefore compared calcium signalling, transcriptional events and melatonin synthesis in the melatonin-deficient C57BL mouse and the melatonin-proficient C3H mouse. Pineal glands and primary pinealocytes were cultured and stimulated with NE or were collected at various times of the light/dark (LD) cycle. Changes in intracellular calcium concentrations, the phosphorylation of CREB, and ICER protein levels follow similar dynamics in the pineal glands of both mouse strains. pCREB levels are high during the early night and ICER protein shows elevated levels during the late night. In the C57BL pineal gland, a low but significant increase in melatonin synthesis could be observed upon NE stimulation, and, notably, also when animals were exposed to long nights. We conclude that the commonly used C57BL mouse is not completely melatonin-deficient and that this melatonin-deficiency does not affect molecular details involved in regulating transcriptional events of melatonin synthesis.
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- 2000
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22. The Pineal Organ, Its Hormone Melatonin, and the Photoneuroendocrine System
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Werner Korf, Christof Schomerus, Jörg H. Stehle, Werner Korf, Christof Schomerus, and Jörg H. Stehle
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- Neurosciences, Cytology, Physiology
- Abstract
Provides comprehensive, updated information on the structure, and cell and molecular biology of the vertebrate pineal organ, which is the source of the'timing hormone'melatonin.
- Published
- 2012
23. Melatonin Excretion Rhythms in the Cultured Pineal Organ of the Lamprey, Lampetra japonica
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T. Kachi, Stuart E. Dryer, Jiri Vanecek, Takashi Yoshimura, Akihito Adachi, Masayuki Hara, Masaomi Iyo, S. Hashimoto, M.F. Xu, D.J. Kennaway, Y. Saito, Sato Honma, Shizufumi Ebihara, Norio Mori, T. Yamauchi, Takuro Endo, P.M. Iuvone, P. Greve, Theresa D'Souza, S. Kajihara, M. Bernard, T. Irie, Katsumi Aida, Yukitomo Morita, Masayuki Iigo, V.M. Cassone, T. Suzuki, Kazuaki Hirata, M. Kurushima, Michikazu Samejima, Ken-ichi Honma, Satoko Hashimoto, Norio Okamoto, Ondrej Slanar, Norio Suzuki, K. Honma, Gregory M. Cahill, Katsuhisa Uchida, P. Pévet, Satoshi Tamotsu, P.L. Tang, Mitsuo Tabata, Horst-W. Korf, Ritsuko Ohtani-Kaneko, H. Kudou, B. Pitrosky, Susanne Kroeber, Takuya Nogi, D.C. Klein, Hana Zemkova, Christof Schomerus, G. Takahashi, N. Kimura, A. Alonso-Gomez, Minoru Hasegawa, Z.M. Qian, Kanjun Hirunagi, and Yutaka Ohashi
- Subjects
endocrine system ,medicine.medical_specialty ,biology ,Lamprey ,Endogeny ,biology.organism_classification ,Melatonin ,Excretion ,Cellular and Molecular Neuroscience ,Rhythm ,Endocrinology ,Developmental Neuroscience ,Neurology ,Internal medicine ,medicine ,Lampetra japonica ,Secretion ,Circadian rhythm ,hormones, hormone substitutes, and hormone antagonists ,medicine.drug - Abstract
Pineal organ of the lamprey, Lampetra japonica, is essential to keep the circadian locomotor activity rhythm as previously reported. In this paper, we tried to show that an endogenous oscillator is located and is working in the pineal organ. When the pineal organs were excised and cultured in a plastic tube with M199 medium at 20 degrees C, melatonin secretion rhythms were clearly observed under both light-dark and continuous dark conditions. The circadian secretion of melatonin continued for more than five cycles under the continuous dark condition. This indicates that the pineal organ has an endogenous oscillator and that the melatonin secretion rhythm is controlled by this oscillator. These findings suggest the possibility that the locomotor activity rhythm of the lamprey is under the control of the oscillator in the pineal organ.
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- 1997
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24. Regulation of the Intracellular Concentration of Free Calcium Ions in Pinealocytes of the Rainbow Trout and the Rat
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Susanne Kroeber, Horst-W. Korf, and Christof Schomerus
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Intracellular Fluid ,medicine.medical_specialty ,Patch-Clamp Techniques ,Light ,chemistry.chemical_element ,Calcium ,Biology ,Pineal Gland ,Calcium in biology ,Pinealocyte ,Norepinephrine ,Cellular and Molecular Neuroscience ,Pineal gland ,Developmental Neuroscience ,Internal medicine ,Cyclic AMP ,medicine ,Animals ,L-type calcium channel ,Patch clamp ,Calcium metabolism ,Voltage-dependent calcium channel ,Rats ,medicine.anatomical_structure ,Endocrinology ,Neurology ,chemistry ,Oncorhynchus mykiss ,Biophysics - Abstract
Together with cAMP, calcium ions play an important role in the regulation of melatonin synthesis in the pineal organ of all vertebrate species, irrespective of the conspicuous phylogenetic transformation of the melatonin-producing cell, the pinealocyte. Here we address the question how the intracellular concentration of free calcium ions [Ca2+]i is regulated in directly light-sensitive trout pinealocytes and in rat pinealocytes which have lost the direct light sensitivity and respond to norepinephrine. Isolated pinealocytes identified by the S-antigen immunoreaction were investigated by means of the fura-2 technique, image analysis and patch clamp recordings. Approximately 30% of the trout pinealocytes exhibited spontaneous [Ca2+]i oscillations that were not affected by light or dark adaptation of the cells. Removal of extracellular Ca2+ or application of 10 microM nifedipine caused a reversible breakdown of the [Ca2+]i oscillations. Treatments with 60 mM KCl and nifedipine suggest that voltage-gated L-type calcium channels play a major role in the regulation of [Ca2+]i in both oscillating and nonoscillating trout pinealocytes. Experiments with thapsigargin (2 microM) revealed the presence of intracellular calcium stores in 80% of the trout pinealocytes, but their role in the regulation of [Ca2+]i remains elusive. Norepinephrine had no apparent effect on [Ca2+]i in any trout pinealocyte. In rat pinealocytes, [Ca2+]i did not show spontaneous oscillations. Norepinephrine evoked a dramatic biphasic rise in [Ca2+]i in more than 95% of the cells via stimulation of alpha1-adrenergic receptors. The response reflects a combination of calcium mobilization from intracellular, thapsigargin-sensitive calcium stores and an increased calcium influx. Voltage-gated calcium channels of the L-type are present in the rat pinealocyte membrane, but they are not involved in the norepinephrine-induced calcium response. These channels, however, mediate the increase in calcium influx which is observed in virtually all rat pinealocytes upon stimulation with acetylcholine or nicotine. The results show that the mechanisms which regulate [Ca2+]i in pinealocytes are complex and differ considerably between poikilothermic and mammalian species.
- Published
- 1997
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25. Contents Vol. 6, 1997
- Author
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Takuya Nogi, Masaomi Iyo, S. Hashimoto, D.C. Klein, Norio Mori, M. Kurushima, D.J. Kennaway, Yutaka Ohashi, Norio Suzuki, Ondrej Slanar, K. Honma, Hana Zemkova, Christof Schomerus, H. Kudou, B. Pitrosky, T. Kachi, P. Pévet, M. Bernard, T. Irie, Satoshi Tamotsu, P.L. Tang, Katsuhisa Uchida, Masayuki Iigo, Kanjun Hirunagi, T. Yamauchi, Norio Okamoto, Satoko Hashimoto, Shizufumi Ebihara, S. Kajihara, Gregory M. Cahill, Z.M. Qian, Theresa D'Souza, M.F. Xu, Mitsuo Tabata, Horst-W. Korf, G. Takahashi, N. Kimura, Takuro Endo, Minoru Hasegawa, Ritsuko Ohtani-Kaneko, Yukitomo Morita, Y. Saito, Susanne Kroeber, Jiri Vanecek, Takashi Yoshimura, A. Alonso-Gomez, T. Suzuki, Katsumi Aida, V.M. Cassone, Michikazu Samejima, Ken-ichi Honma, Stuart E. Dryer, Akihito Adachi, P. Greve, Kazuaki Hirata, Masayuki Hara, Sato Honma, and P.M. Iuvone
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Cellular and Molecular Neuroscience ,Developmental Neuroscience ,Neurology - Published
- 1997
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26. Melatonin Receptors in the Spinal Cord
- Author
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Michikazu Samejima, Ken-ichi Honma, T. Kachi, Gregory M. Cahill, P. Pévet, Ritsuko Ohtani-Kaneko, A. Alonso-Gomez, Hana Zemkova, Theresa D'Souza, Satoko Hashimoto, Takuro Endo, M. Bernard, Norio Mori, Susanne Kroeber, T. Suzuki, Christof Schomerus, M.F. Xu, Masayuki Hara, Shizufumi Ebihara, P.L. Tang, Sato Honma, Yukitomo Morita, P.M. Iuvone, Takuya Nogi, D.C. Klein, D.J. Kennaway, P. Greve, Katsuhisa Uchida, Katsumi Aida, V.M. Cassone, T. Irie, M. Kurushima, Kazuaki Hirata, Stuart E. Dryer, Akihito Adachi, Mitsuo Tabata, Horst-W. Korf, Y. Saito, K. Honma, Z.M. Qian, T. Yamauchi, S. Kajihara, Jiri Vanecek, Takashi Yoshimura, Ondrej Slanar, G. Takahashi, N. Kimura, Norio Suzuki, Satoshi Tamotsu, H. Kudou, B. Pitrosky, Yutaka Ohashi, Kanjun Hirunagi, Masaomi Iyo, S. Hashimoto, Masayuki Iigo, Norio Okamoto, and Minoru Hasegawa
- Subjects
medicine.medical_specialty ,business.industry ,Spinal cord ,Melatonin ,Cellular and Molecular Neuroscience ,Endocrinology ,medicine.anatomical_structure ,Developmental Neuroscience ,Neurology ,Internal medicine ,medicine ,Receptor ,business ,medicine.drug - Published
- 1997
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27. Calcium oscillations in a subpopulation of S-antigen-immunoreactive pinealocytes of the rainbow trout (Oncorhynchus mykiss)
- Author
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Susanne Kroeber, Christof Schomerus, and Horst-Werner Korf
- Subjects
Male ,Periodicity ,medicine.medical_specialty ,Thapsigargin ,chemistry.chemical_element ,Calcium ,Pineal Gland ,Calcium in biology ,Membrane Potentials ,Pinealocyte ,Norepinephrine ,chemistry.chemical_compound ,Internal medicine ,medicine ,Extracellular ,Animals ,L-type calcium channel ,Sympathomimetics ,Molecular Biology ,Cells, Cultured ,Phylogeny ,biology ,Voltage-dependent calcium channel ,Histocytochemistry ,General Neuroscience ,S100 Proteins ,biology.organism_classification ,Immunohistochemistry ,Trout ,Endocrinology ,Microscopy, Fluorescence ,chemistry ,Oncorhynchus mykiss ,Biophysics ,Female ,Calcium Channels ,Neurology (clinical) ,Fura-2 ,Developmental Biology - Abstract
By means of the fura-2 technique and image analysis the intracellular concentration of free calcium ions [Ca 2+ ] i was examined in isolated rainbow trout pinealocytes identified by S-antigen immunocytochemistry. Approximately 30% of the pinealocytes exhibited spontaneous [Ca 2+ ] i oscillations whose frequency differed from cell to cell. Neither illumination with bright light nor dark adaptation of the cells had an apparent effect on the oscillations. Removal of extracellular Ca 2+ or application of 10 μ M nifedipine caused a reversible breakdown of the [Ca 2+ ] i oscillations. Application of 60 mM KCl elevated [Ca 2+ ] i in 90% of the oscillating and 50% of the non-oscillating pinealocytes. The effect of KCl was blocked by 50 μ M nifedipine. These results suggest that voltage-gated L-type calcium channels play a major role in the regulation of [Ca 2+ ] i in trout pinealocytes. Experiments with thapsigargin (2 μ M) revealed the presence of intracellular calcium stores in 80% of the trout pinealocytes, but their role for regulation of [Ca 2+ ] i remains elusive. Treatment with norepinephrine (100 pM–50 μ M), previously shown to induce calcium release from intracellular calcium stores in rat pinealocytes, had no apparent effect on [Ca 2+ ] i in any trout pinealocyte. This finding conforms to the concept that noradrenergic mechanisms are not involved in signal transduction in the directly light-sensitive pineal organ of anamniotic vertebrates.
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- 1997
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28. Norepinephrine-induced phosphorylation of the transcription factor CREB in isolated rat pinealocytes: an immunocytochemical study
- Author
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Jörg H. Stehle, Horst-Werner Korf, Satoshi Tamotsu, Patrick H. Roseboom, and Christof Schomerus
- Subjects
Male ,Agonist ,medicine.medical_specialty ,Histology ,medicine.drug_class ,Stimulation ,Propranolol ,Biology ,CREB ,Pineal Gland ,Pathology and Forensic Medicine ,Pinealocyte ,Norepinephrine (medication) ,Norepinephrine ,Phenylephrine ,Pineal gland ,Antibody Specificity ,Internal medicine ,medicine ,Animals ,Phosphorylation ,Rats, Wistar ,Cyclic AMP Response Element-Binding Protein ,Receptor ,Cells, Cultured ,Colforsin ,Isoproterenol ,Cell Biology ,Adrenergic beta-Agonists ,Immunohistochemistry ,Rats ,medicine.anatomical_structure ,Endocrinology ,biology.protein ,Adrenergic alpha-Agonists ,Transcription Factors ,medicine.drug - Abstract
In the present study we investigated whether norepinephrine, which stimulates melatonin biosynthesis in the mammalian pineal organ, causes phosphorylation of the cyclic AMP responsive element binding protein (CREB) in rat pinealocytes. Cells isolated from the pineal organ of adult male rats and cultured on coated coverslips were treated with norepinephrine, beta- or alpha 1-adrenergic agonists for 12, 5, 10, 20, 30, 60 or 300 min and then immunocytochemically analyzed with an antibody against phosphorylated CREB (p-CREB). Treatment with norepinephrine or beta-adrenergic agonists resulted in a similar, time-dependent induction of p-CREB immunoreactivity, exclusively found in cell nuclei. The alpha 1-adrenergic agonist phenylephrine did not induce p-CREB immunoreactivity at low doses (0.1 microM) or when high doses (10 microM) were applied in combination with a beta-antagonist (propranolol, 0.1 microM). This indicates that induction of CREB phosphorylation is elicited by beta-adrenergic receptor stimulation. The response was first seen after 10 min and reached a maximum after 30 to 60 min when more than 90% of the cells displayed p-CREB immunoreactivity. The intensity of the p-CREB immunoreactivity showed marked cell-to-cell variation, but nearly all immunoreactive cells were identified as pinealocytes by double-labeling with an antibody against the S-antigen, a pinealocyte-specific marker. The results show that norepinephrine stimulation induces p-CREB immunoreactivity by acting upon beta-adrenergic receptors in virtually all rat pinealocytes. The findings support the notion that phosphorylation of CREB is a rather rapid and uniform response of pinealocytes to noradrenergic stimulation and thus is an important link between adrenoreceptor activation and subsequent gene expression in the rat pineal organ.
- Published
- 1995
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29. CDC25-dependent induction of inositol 1,4,5-trisphosphate and diacylglycerol inSaccharomyces cerevisiaeby nitrogen
- Author
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Hans Küntzel and Christof Schomerus
- Subjects
Nitrogen ,Saccharomyces cerevisiae ,Biophysics ,Cell Cycle Proteins ,Biology ,Biochemistry ,Diglycerides ,Fungal Proteins ,Adenylyl cyclase ,Radioligand Assay ,chemistry.chemical_compound ,Phosphoinositide Phospholipase C ,Phospholipase C ,Structural Biology ,Inositol 1,4,5-trisphosphate ,Diacyl glycerol ,Genetics ,Inositol ,Diglyceride ,Inositol phosphate ,Molecular Biology ,Diacylglycerol kinase ,chemistry.chemical_classification ,CDC25 ,Phosphoric Diester Hydrolases ,ras-GRF1 ,Phosphatidylinositol Diacylglycerol-Lyase ,Cell Biology ,biology.organism_classification ,Nitrogen signalling ,chemistry ,Second messenger system ,Signal Transduction - Abstract
The addition of ammonium sulfate to starved yeast cells leads to a 3- to 4-fold rapid increase of the second messengers inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG), the products of phosphoinositide-specific phospholipase C (PI-PLC). This response is reduced by dissecting the RAS-activating Cdc25 protein, and is completely abolished by the cdc25-1 mutation even at permissive temperature. Starved cdc25-1 mutant cells have a strongly reduced IP3 content, but an at least 10-fold increased DAG level compared to the isogenic wild-type strain. NH4 does not stimulate cAMP synthesis, and glucose does not induce IP3 and DAG. Our data suggest that the Cdc25 protein controls a nitrogen-specific signalling pathway involving the effector PI-PLC, in addition to the glucose-induced activation of adenylyl cyclase (AC).
- Published
- 1992
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30. Site-directed mutagenesis of the Saccharomyces cerevisiae CDC25 gene: effects on mitotic growth and cAMP signalling
- Author
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Christof Schomerus, Thomas Munder, and Hans Küntzel
- Subjects
Genes, Fungal ,Molecular Sequence Data ,Restriction Mapping ,Mutant ,Saccharomyces cerevisiae ,Mitosis ,Adenylate kinase ,Cell Cycle Proteins ,Fungal Proteins ,Ras-GRF1 ,Cyclic AMP ,Genetics ,Amino Acid Sequence ,Cloning, Molecular ,Phosphorylation ,Site-directed mutagenesis ,Molecular Biology ,Fungal protein ,Base Sequence ,biology ,ras-GRF1 ,biology.organism_classification ,Cell biology ,Biochemistry ,Mutagenesis, Site-Directed ,biology.protein ,CREB1 ,Signal Transduction - Abstract
A potential membrane-interacting site within the essential growth-controlling carboxy-terminal region of the CDC25 protein was interrupted by a lethal mutation (1461 Tyr----Asp and 1462 Leu----Arg). The elimination of two potential phosphorylation sites found in the same region (1489 Thr----Pro and 1584 Ser----Pro) does not affect growth but completely prevents glucose-induced cAMP signalling in the double mutant, whereas the single mutants produce normal or slightly retarded cAMP signals. A cluster of five potential targets for cAMP-dependent phosphorylation at the amino-terminal region could be deleted without affecting phenotypic properties. It is concluded that the carboxy-terminal 137 residues of the CDC25 protein are involved in three different functions: control of mitotic growth, glucose-induced hyperactivation of adenylate cyclase, and feed-back inhibition of cAMP synthesis.
- Published
- 1990
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31. Dephosphorylation of pCREB by protein serine/threonine phosphatases is involved in inactivation of Aanat gene transcription in rat pineal gland
- Author
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Marco, Koch, Viviane, Mauhin, Jörg H, Stehle, Christof, Schomerus, and Horst-Werner, Korf
- Subjects
Male ,Transcription, Genetic ,Arylamine N-Acetyltransferase ,Immunoblotting ,In Vitro Techniques ,Immunohistochemistry ,Pineal Gland ,Rats ,Cyclic AMP Response Element Modulator ,DNA-Binding Proteins ,Isoenzymes ,Repressor Proteins ,Norepinephrine ,Protein Subunits ,Catalytic Domain ,Phosphoprotein Phosphatases ,Animals ,RNA, Messenger ,Enzyme Inhibitors ,Phosphorylation ,Rats, Wistar ,Cyclic AMP Response Element-Binding Protein ,Cells, Cultured ,Melatonin - Abstract
The rat pineal gland is a suitable model to investigate neurotransmitter-controlled gene expression, because it is well established that the stimulation of melatonin biosynthesis by norepinephrine (NE) depends on the activation of the gene that encodes arylalkylamine N-acetyltransferase (AANAT), the melatonin rhythm enzyme. The mechanisms responsible for downregulation of Aanat transcription are less clear. In this in vitro study we investigated the role of pCREB dephosphorylation for termination of Aanat gene transcription. Immunosignals for pCREB, strongly induced after NE stimulation, rapidly decreased after withdrawal of NE. The immunoreactivity of the inhibitory transcription factor ICER increased twofold after NE treatment for 6 h, but did not change within 30 min after removal of the stimulus. Application of protein serine/threonine phosphatase (PSP) inhibitors prevented pCREB dephosphorylation and blocked the decreases in Aanat mRNA levels, AANAT protein amount and melatonin biosynthesis all of which occurred rapidly after NE withdrawal. PSPs in the rat pineal gland were characterized by immunocytochemistry and immunoblotting. NE-stimulation for 8 h induced accumulation of PSP1-catalytic subunit (CSU) in pinealocyte nuclei, but did not affect the distribution of PSP2A-CSU. The results identify dephosphorylation of pCREB by PSPs as an essential mechanism for downregulation of Aanat transcription in the rat pineal gland.
- Published
- 2003
32. Norepinephrine-dependent phosphorylation of the transcription factor CREB in bovine pinealocytes
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Elke Laedtke, Christof Schomerus, and Horst-Werner Korf
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ATF/CREB ,Sp1 transcription factor ,biology ,General transcription factor ,Chemistry ,TAF2 ,biology.protein ,CREB ,Transcription factor ,Activating transcription factor 2 ,Cell biology ,Pinealocyte - Published
- 2003
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33. Norepinephrine-dependent phosphorylation of the transcription factor cyclic adenosine monophosphate responsive element-binding protein in bovine pinealocytes
- Author
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Christof, Schomerus, Elke, Laedtke, and Horst-Werner, Korf
- Subjects
Norepinephrine ,Animals ,Cattle ,Phosphorylation ,Cyclic AMP Response Element-Binding Protein ,Immunohistochemistry ,Pineal Gland ,Cells, Cultured - Abstract
Norepinephrine (NE)-dependent activation of transcription factors is of central importance for the rhythmic production of melatonin in the rodent pineal gland. At variance with rodents, NE regulates melatonin biosynthesis through post-translational mechanisms in ungulates, and it is not yet known whether transcription factors play any role in ungulate pineal functions. Here, we investigated in isolated bovine pinealocytes the NE-dependent phosphorylation of the transcription factor cyclic adenosine monophosphate (cAMP) responsive element-binding protein (CREB) and compared the effects of NE with those of vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP). Treatment with 10(-7) m NE for 30 min induced a strong nuclear phosphorylated CREB (pCREB) immunoreaction in cells that were identified as pinealocytes by immunocytochemical demonstration of serotonin, a pinealocyte-specific marker. Immunoblots showed that the NE-induced immunoreaction was due to phosphorylation of the transcription factor CREB and another protein, presumably the activating transcription factor 1 (ATF-1). 10(-7) m isoproterenol (ISO) or 10(-5) m forskolin mimicked the response to NE indicating that NE acts through the beta-adrenergic/cAMP pathway. Also 10(-7) m PACAP, but not 10(-7) m VIP-enhanced CREB phosphorylation; however, only a subpopulation of cells was responsive to PACAP. Our results suggest that, irrespective of whether or not melatonin production is controlled via transcriptional mechanisms, NE-induced CREB phosphorylation represents a very conserved element in pineal physiology of mammals because NE increases pCREB levels in all mammalian species investigated so far. However, the genes targeted by pCREB may vary from one mammalian species to the other. Our results also suggest that transcription factors other than pCREB, like ATF-1, may play a role in pineal functions of mammals.
- Published
- 2003
34. Signal Transduction in The Rodent Pineal Organ
- Author
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James Olcese, Charlotte von Gall, Martina Pfeffer, Jörg H. Stehle, Helmut Wicht, Erik Maronde, Christof Schomerus, Faramarz Dehghani, Susanne Kroeber, and Horst-Werner Kork
- Subjects
endocrine system ,Biology ,Cell biology ,Melatonin ,Pineal gland ,medicine.anatomical_structure ,Acetyltransferase ,Second messenger system ,Arylalkylamine ,medicine ,Post-translational regulation ,Signal transduction ,Transduction (physiology) ,hormones, hormone substitutes, and hormone antagonists ,medicine.drug - Abstract
SUMMARY The rodent pineal organ transduces a photoneural input into a hormonal output. This photoneuroendocrine transduction leads to highly elevated levels of the hormone melatonin at nightime which serves as a message for darkness. The melatonin rhythm depends on transcriptional, translational and posttranslational regulation of the arylalkylamine- N -acetyltransferase, the key enzyme of melatonin biosynthesis. These regulatory mechanisms are fundamentally linked to two second messenger systems, namely the C AMP- and the Ca 2+ -signal transduction pathways. Our data gained by molecular biology, immunohistochemistry and single-cell imaging demonstrate a time-and substance-specific activation of these signaling pathways and provide a framework for the understanding of the complex signal transduction cascades in the rodent pineal gland which in concert not only regulate the basic profile but also finetune the circa-dian rhythm in melatonin synthesis. Melatonin after Four Decades, edited by James Olcese.Kluwer Academic / Plenum Publishers, New York, 2000.
- Published
- 2002
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35. Of rodents and ungulates and melatonin: creating a uniform code for darkness by different signaling mechanisms
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Jörg H. Stehle, Charlotte von Gall, Horst-Werner Korf, and Christof Schomerus
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0301 basic medicine ,Primates ,endocrine system ,Cellular adaptation ,Physiology ,Circadian clock ,Rodentia ,CREB ,Pinealocyte ,Melatonin ,03 medical and health sciences ,Pineal gland ,0302 clinical medicine ,Physiology (medical) ,medicine ,Animals ,Humans ,Artiodactyla ,Chronobiology Phenomena ,biology ,Activator (genetics) ,Darkness ,CLOCK ,030104 developmental biology ,medicine.anatomical_structure ,Biochemistry ,biology.protein ,030217 neurology & neurosurgery ,medicine.drug ,Signal Transduction - Abstract
Melatonin synthesis in the mammalian pineal gland is one of the best investigated output pathways of the circadian clock because it can be readily measured and is tightly regulated by a clearly defined input, the neurotransmitter norepinephrine. In this system, a regulatory scenario was deciphered that is centered around the cyclic AMP pathway but shows peculiar species-specific differences. In rodents, the cyclic AMP–mediated, temporally sequential up-regulation of two transcription factors, the activator CREB (cyclic AMP–responsive elementbinding protein) and the inhibitor ICER (inducible cyclic AMP–dependent early repressor), is the core mechanism to determine rhythmic accumulation of the mRNA encoding for the rate-limiting enzyme in melatonin synthesis, the arylalkylamine N-acetyltransferase (AA-NAT). Thus, in rodents, the regulation of melatonin synthesis bears an essential transcriptional component, which, however, is flanked by posttranscriptional mechanisms. In contrast, in ungulates, and possibly also in primates, AA-NAT appears to be regulated exclusively on the posttranscriptional level. Here, increasing cyclic AMP levels inhibit the breakdown of constitutively synthesized AA-NAT protein by proteasomal proteolysis, leading to an elevated enzyme activity. Thus, self-restriction of cellular responses, as a reaction to external cues, is accomplished by different mechanisms in pinealocytes of different mammalian species. In such a temporally gated cellular adaptation, transcriptionally active products of clock genes may play a supplementary role. Their recent detection in the endogenously oscillating nonmammalian pineal organ and, notably, also in the slave oscillator of the mammalian pineal gland underlines that the mammalian pineal gland will continue to serve as an excellent model system to understand mechanisms of biological timing.
- Published
- 2001
36. Analyses of signal transduction cascades in rat pinealocytes reveal a switch in cholinergic signaling during postnatal development
- Author
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Horst-Werner Korf, Christof Schomerus, and Elke Laedtke
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Male ,medicine.medical_specialty ,Aging ,CREB ,Pineal Gland ,Pinealocyte ,Norepinephrine ,Calcium imaging ,Internal medicine ,Muscarinic acetylcholine receptor ,medicine ,Animals ,Receptors, Cholinergic ,Calcium Signaling ,Phosphorylation ,Cyclic AMP Response Element-Binding Protein ,Molecular Biology ,Calcium signaling ,biology ,General Neuroscience ,Neuropeptides ,Acetylcholine ,Rats ,Endocrinology ,Nicotinic agonist ,Animals, Newborn ,biology.protein ,Cholinergic ,Pituitary Adenylate Cyclase-Activating Polypeptide ,Neurology (clinical) ,Developmental Biology ,medicine.drug ,Signal Transduction ,Vasoactive Intestinal Peptide - Abstract
In the rat pineal gland, norepinephrine activates α1- and β-adrenergic receptors and triggers melatonin production through an increase in the intracellular calcium concentration ([Ca2+]i) and stimulation of the cAMP/cAMP responsive element-binding protein (CREB) cascade. VIP and PACAP also elevate the intracellular cAMP level and promote melatonin formation. Finally, ACh antagonizes the norepinephrine-induced hormone synthesis via nicotinic acetylcholine receptors and subsequent activation of voltage-gated calcium channels. By immuno(cyto)chemical demonstration of phosphorylated CREB and calcium imaging we have investigated the temporal relationship between the maturation of these signaling pathways and the rhythmic onset of melatonin biosynthesis in developing rat pinealocytes. Norepinephrine-regulated calcium signaling and phosphorylation of CREB are already fully developed at birth, i.e., prior to ingrowth of the sympathetic innervation into the pineal parenchyma, and appear to develop in an innervation-independent manner. VIP- and PACAP-induced CREB phosphorylation is restricted to subpopulations of neonatal cells and thus also displays an adult pattern. Cholinergic calcium signaling exhibits a developmental switch within the first three postnatal weeks. In neonatal pinealocytes, acetylcholine elevates [Ca2+]i via muscarinic rather than nicotinic acetylcholine receptors. In the second postnatal week, pinealocytes gain responsiveness to nicotine and gradually lose responsiveness to muscarinic cholinergic stimuli. Voltage-gated calcium channels are absent in neonatal cells and develop during the first postnatal days. ACh-evoked cellular events may be diversified depending on the functional subclass of receptor that is present. The transient existence of muscarinic acetylcholine receptors and the subsequent switch to nicotinic receptors would permit ACh to elicit temporary effects in early pineal development.
- Published
- 1999
37. Cholinergic signal transduction cascades in rat pinealocytes: functional and ontogenetic aspects
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Horst-Werner Korf, Christof Schomerus, and Revues Inra, Import
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medicine.medical_specialty ,Sympathetic Nervous System ,chemistry.chemical_element ,Nerve Tissue Proteins ,Calcium ,Biology ,Receptors, Nicotinic ,Pineal Gland ,Calcium in biology ,Pinealocyte ,Norepinephrine ,Internal medicine ,Muscarinic acetylcholine receptor ,[SDV.BDD] Life Sciences [q-bio]/Development Biology ,medicine ,Animals ,Calcium Signaling ,[SDV.BDLR] Life Sciences [q-bio]/Reproductive Biology ,Ion Transport ,Voltage-dependent calcium channel ,Age Factors ,Gene Expression Regulation, Developmental ,Receptors, Muscarinic ,Acetylcholine ,Cell biology ,Rats ,[SDV.AEN] Life Sciences [q-bio]/Food and Nutrition ,Metabotropic receptor ,Nicotinic agonist ,Endocrinology ,chemistry ,Cholinergic Fibers ,Calcium Channels ,medicine.drug - Abstract
In adult rat pinealocytes, acetylcholine activates nicotinic receptors whose stimulation causes a depolarization of the cells, opening of voltage-gated cation channels of the L-type and sub- sequent increase in the intracellular calcium ion concentration. These events trigger a release of glu- tamate that, by its action on metabotropic glutamate type 3 receptors, activates an inhibitory cyclic AMP cascade and suppresses norepinephrine-induced melatonin biosynthesis. The nicotinic res- ponse is fully developed in the third postnatal week. Prior to this timepoint, rat pinealocytes possess functional muscarinic receptors whose activation causes a rise in the intracellular calcium ion concen- tration through a calcium release from thapsigargin-sensitive intracellular calcium stores and an opening of store-operated calcium channels. This cascade may influence tissue differentiation and matu- ration of the melatonin pathway. The demonstration of functional cholinoreceptors and the ontoge- netic switch from muscarinic to nicotinic signalling in rat pinealocytes supports the concept that pineal functions in mammals are influenced by neuronal inputs other than the sympathetic innerva- tion which serves as the major regulatory system. © Inra/Elsevier, Paris
- Published
- 1999
38. Control of CREB phosphorylation and its role for induction of melatonin synthesis in rat pinealocytes
- Author
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Christof Schomerus, Jörg H. Stehle, Horst-Werner Korf, and Erik Maronde
- Subjects
endocrine system ,medicine.medical_specialty ,Transcription, Genetic ,Cyclic AMP-Dependent Protein Kinase Type II ,Biology ,CREB ,Pineal Gland ,Pinealocyte ,Melatonin ,Pineal gland ,Norepinephrine ,Organ Culture Techniques ,Internal medicine ,medicine ,Cyclic AMP ,Animals ,Phosphorylation ,Protein kinase A ,Cyclic AMP Response Element-Binding Protein ,Cells, Cultured ,Kinase ,Neuropeptides ,Cell Biology ,General Medicine ,Cyclic AMP-Dependent Protein Kinases ,Circadian Rhythm ,Rats ,Receptors, Adrenergic ,medicine.anatomical_structure ,Endocrinology ,Gene Expression Regulation ,biology.protein ,Pituitary Adenylate Cyclase-Activating Polypeptide ,Signal transduction ,Protein Processing, Post-Translational ,hormones, hormone substitutes, and hormone antagonists ,medicine.drug ,Signal Transduction ,Vasoactive Intestinal Peptide - Abstract
Phosphorylation of the transcription factor CREB appears as an important step in the signal transduction cascade that activates melatonin biosynthesis in the mammalian pineal organ. We have studied the mechanisms causing CREB phosphorylation by immunocytochemical and immunochemical demonstration of phosphorylated CREB (pCREB) in isolated, immunocytochemically identified rat pinealocytes kept in vitro and in the rat pineal organ in situ. Norepinephrine (NE), the most potent stimulator of the melatonin biosynthesis was shown to induce pCREB immunoreaction (i.r.) in the vast majority of pinealocytes in a time- and dose-dependent manner. This response was elicited by stimulation of beta-adrenergic receptors resulting in an increase in the intracellular cAMP concentration. Activation of alpha 1-adrenergic receptors that causes a rise in intracellular calcium via stimulation of intracellular stores and subsequent increase in calcium influx did not evoke pCREB ir on its own and did not potentiate the beta-adrenergic response. VIP and PACAP that activate the melatonin biosynthesis to a lesser extent than NE induced pCREB ir in only 50-60% of the pinealocytes. Immunoblotting showed that a protein of 43 kDa corresponding to CREB accounts for the pCREB ir and confirmed that VIP and PACAP are less effective in inducing CREB phosphorylation than NE. The amount of total (phosphorylated and unphosphorylated) CREB was not changed upon stimulation of the cells with NE, VIP or PACAP. In an attempt to identify the protein kinase catalyzing CREB phosphorylation in rat pinealocytes, the cAMP-dependent protein kinases (cAK) present in the rat pineal were identified with the use of antibodies recognizing different catalytic and regulatory subunits. Application of cAK agonists and antagonists showed that the cAK type II is responsible for CREB phosphorylation. Correlations between the melatonin concentration in the medium and the CREB phosphorylation in pinealocytes revealed a tight connection between these two parameters. Phosphorylation of CREB appears important for the stimulation of melatonin biosynthesis also under natural conditions because our investigations of whole pineal organs taken from rats during different time points of the 24 h light-dark cycle revealed a strong induction of pCREB ir in the first part of the night.
- Published
- 1998
39. A specific and sensitive double-immunofluorescence method for the demonstration of S-antigen and serotonin in trout and rat pinealocytes by means of primary antibodies from the same donor species
- Author
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Horst-Werner Korf, Susanne Kroeber, and Christof Schomerus
- Subjects
Male ,Serotonin ,Histology ,Cell ,Pineal Gland ,Sensitivity and Specificity ,Antibodies ,Pinealocyte ,Antigen ,medicine ,Animals ,Frozen Sections ,Binding site ,Fluorescent Antibody Technique, Indirect ,Molecular Biology ,Cells, Cultured ,Frozen section procedure ,Arrestin ,biology ,Cell Biology ,biology.organism_classification ,Primary and secondary antibodies ,Molecular biology ,Rats ,Medical Laboratory Technology ,Trout ,medicine.anatomical_structure ,Oncorhynchus mykiss ,biology.protein ,Female ,Rabbits ,Antibody - Abstract
Immunocytochemical double-labeling methods are important tools in cell and neurobiology. Here we describe a method which is based on double immunofluorescence and allows specific detection of two different antigens located in the same cell compartment by two primary antibodies raised in the same species. As an example, we present the double-immunolabeling method for the S-antigen (SAg), a photoreceptor-specific protein, and the indoleamine serotonin (5HT) in dissociated trout and rat pineal cells immobilized on coverslipped and in frozen sections of the trout pineal organ. As a first step, the preparations on the slides or coverslips were sequentially incubated with the first primary antibody (rabbit anti-SAg), the fluorescein-labeled (anti-rabbit) secondary antibody, and then with normal rabbit serum. Meanwhile, the second primary antibody (rabbit anti-5HT) was coupled to a Cy3-labeled secondary (anti-rabbit) antibody in a reaction tube and excess binding sites were quenched with normal rabbit serum. This complex was applied to the specimens after completion of the first (SAg) immunoreaction on the slide. For control experiments, the first (anti-SAg) or the second (anti-5HT) primary antibody were omitted. Most of the rat and trout pinealocytes were double immunolabeled for SAg and 5HT. In the trout, few cells contained SAg or 5HT immunoreaction only. This underlines the selectivity of each immunoreaction. The results show that the method can be used for the analysis of whole cells and tissue sections by means of conventional fluorescence and confocal laser scanning microscopy.
- Published
- 1998
40. Receptor Mechanisms and Second Messenger Systems Involved in the Regulation of the Melatonin Biosynthesis
- Author
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Christof Schomerus, Horst-W. Korf, and Jörg H. Stehle
- Subjects
endocrine system ,medicine.medical_specialty ,Endogeny ,Pinealocyte ,Melatonin ,chemistry.chemical_compound ,Endocrinology ,Biosynthesis ,chemistry ,Internal medicine ,Second messenger system ,medicine ,Secretion ,Circadian rhythm ,Receptor ,hormones, hormone substitutes, and hormone antagonists ,medicine.drug - Abstract
According to current concepts, the highly lipophilic melatonin is not stored within the pinealocytes but is released into pineal capillaries immediately after its formation. Thus the secretion of melatonin appears to be controlled solely by its biosynthesis, which is catalyzed by four distinct enzymes: TPH, aromatic L-amino acid decarboxylase, NAT, and HIOMT (Fig. 4). In all vertebrate species studied so far, melatonin reaches its maximal concentration during the night and is nearly undetectable during daytime. This rhythm has been shown to depend on the large increase in concentration and activity of the NAT that occurs night by night and increases the concentration of N-acetylserotonin which accelerates melatonin synthesis through a mass action effect on HIOMT (Fig. 4). Thus NAT appears as the rate-limiting enzyme of the melatonin biosynthesis and as a molecular interface at which all inputs regulating melatonin production and secretion converge. These inputs are provided by endogenous (circadian) oscillators and photoreceptors.
- Published
- 1998
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41. Phylogenetic Development and Gross Anatomy of the Pineal Complex
- Author
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Christof Schomerus, Horst-W. Korf, and Jörg H. Stehle
- Subjects
Pathology ,medicine.medical_specialty ,Habenular nuclei ,biology ,Suprachiasmatic nucleus ,Anatomy ,Commissure ,Diencephalon ,Skull ,medicine.anatomical_structure ,biology.animal ,medicine ,Gross anatomy ,Parietal foramen ,Hagfish - Abstract
Development and gross anatomy of the pineal complex have been repeatedly and comprehensively dealt with (Studnicka 1905; Bargmann 1943; Vollrath 1981; Korf and Oksche 1986; Korf 1994); thus this chapter reviews only some basic facts (Fig. 2). The pineal develops from a circumscribed area of the diencephalic roof between the habenular and posterior commissures. Interestingly, the other key components of the photoneuroendocrine system, the retina and the suprachiasmatic nucleus, are also derivatives of the diencephalon. With a few exceptions (e.g., hagfish, crocodiles), a pineal complex is present in all vertebrates investigated thus far. In many species whose pineal complex is endowed with functional photoreceptor cells the tissues overlying the pineal region display peculiar specializations; the most pronounced is the parietal foramen of the skull, which is already present in fossils, suggesting the existence of a pineal complex in Silurian and Devonian vertebrates, the ancestors of recent fish, amphibians, and lacertilians. In several recent vertebrates the pineal complex is divided into two distinct components.
- Published
- 1998
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42. Action, Targets, and Receptors of Melatonin
- Author
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Jörg H. Stehle, Horst-W. Korf, and Christof Schomerus
- Subjects
medicine.medical_specialty ,biology ,Suprachiasmatic nucleus ,Xenopus ,biology.organism_classification ,Chromatophore ,Melatonin receptor ,Melatonin ,Endocrinology ,Internal medicine ,Darkness ,medicine ,Circadian rhythm ,Receptor ,hormones, hormone substitutes, and hormone antagonists ,medicine.drug - Abstract
Melatonin is the hormone providing animals and humans with information on the length of the night and thereby also on the length of the day. In amphibians it elicits the primary chromatic response, i.e., blanching of the skin in darkness, by causing pigment aggregation in dermal melanophores (Rollag 1988; Fig. 5). This well-known action was used as a bioassay when Lerner and colleagues isolated melatonin in the late 1950s, and dermal melanophores of the frog Xenopus laevis served as the source for the first molecular biological identification of the melatonin receptor (Ebisawa et al. 1994). In birds melatonin is necessary for maintaining normal circadian function and imposes periodicity on structures that ultimately control overt circadian rhythms (Cassone 1990). In mammals melatonin can entrain circadian rhythms and acts in concert with light to keep the circadian rhythm in phase with prevailing environmental conditions (Arendt 1995; Lewy et al. 1992). Thus melatonin is useful to treat jet lag and some circadian sleeping disorders of humans (Arendt 1995). Moreover, melatonin is involved in regulating reproduction in seasonally breeding mammals (Reiter 1991).
- Published
- 1998
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43. Pineal Transcription Factors and Their Possible Roles for the Regulation of the Melatonin Biosynthesis
- Author
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Jörg H. Stehle, Christof Schomerus, and Horst-W. Korf
- Subjects
medicine.medical_specialty ,biology ,DNA polymerase ,Chemistry ,Promoter ,Cell biology ,Endocrinology ,Internal medicine ,medicine ,biology.protein ,cAMP-dependent pathway ,Nuclear protein ,Protein kinase A ,Enhancer ,Transcription factor ,Gene - Abstract
In recent years considerable progress has been made toward identifying pineal transcription factors and their possible role for the control of melatonin biosynthesis. These studies (nearly all of them performed with mammals) have highlighted the importance of transcription factors that are controlled by the NE/cAMP pathway and impinge on genes bearing a promoter element sensitive to elevation of intracellular cAMP levels (CRE, see below). An essential component of this transmembrane signaling pathway is the cAMP-inducible protein kinase A (PKA). This enzyme consists of catalytic and regulatory subunits (see Maronde et al. 1997a) which are aggregated under resting conditions but dissociate upon cAMP elevation. The catalytic subunits of the PKA phosphorylate constitutively expressed proteins in the cytoplasm and/or - upon translocation into the nucleus - nuclear proteins, as transcription factors. Transcription factors can bind to promotor and enhancer sequences located on genes upstream of the start site of DNA transcription to modulate the activity of DNA polymerases. This leads to an activation or inhibition of DNA transcription and constitutes a fundamental link between an external cue and an adaptive cellular response to appropriately react in time and space.
- Published
- 1998
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44. Pineal Cell Biology and Innervation
- Author
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Jörg H. Stehle, Horst-W. Korf, and Christof Schomerus
- Subjects
Melatonin ,Synaptic ribbon ,Neurofilament ,medicine.anatomical_structure ,Habenular nuclei ,Ultrastructure ,medicine ,Connective tissue ,Basal lamina ,Biology ,Pinealocyte ,medicine.drug ,Cell biology - Abstract
In comparative terms, pinealocytes, supporting (glial) cells, and neurons form the pineal parenchyma which is separated from the adjacent connective tissue layer (capsule) and the capillaries by a basal lamina. Pinealocytes display striking variation among different classes of vertebrates. Based on structural and ultrastructural criteria they have been divided into three main categories: true pineal photoreceptors, modified pineal photoreceptors, and pinealocytes sensu stricto (Oksche 1965, 1971; Collin 1971; Collin and Oksche 1981; Korf and Oksche 1986; Korf 1994; Figs. 2, 8). Since the pioneering work of Dodt and Heerd (1962) the direct light sensitivity of true pineal photoreceptors has been firmly established. The fact that modified photoreceptor cells are also capable of perceiving light stimuli has been known since Deguchi’s discovery in 1981 that, in the chicken, melatonin production is regulated by light perceived in the pineal organ. The direct light sensitivity has been lost in the mammalian pinealocyte. Nevertheless, all pinealocyte types appear to be closely related and can be classified as cells of the receptor line. This intimate relationship has been substantiated by immunocytochemical and biochemical studies showing that neuroendocrine pinealocytes of mammals express “photoreceptor-specific” molecules which otherwise are synthesized only by functional (retinal and pineal) photoreceptor cells (Korf et al. 1985a,b, 1986a,b, 1992; Huang et al. 1992; Kramm et al. 1993; Figs. 9, 10). As holds true for primary sensory cells, all types of pinealocytes belong to the neuronal cell lineage because they express a variety of markers typical of neurons and neuroendocrine cells (neurofilament, synaptobrevin). Pinealocytes can thus be considered as specialized neurons.
- Published
- 1998
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45. Stimulation of a nicotinic ACh receptor causes depolarization and activation of L-type Ca2+ channels in rat pinealocytes
- Author
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C Korbmacher, Erik Maronde, Horst-W. Korf, B Letz, and Christof Schomerus
- Subjects
Nicotine ,Potassium Channels ,Charybdotoxin ,Nifedipine ,Physiology ,Receptors, Nicotinic ,Sodium Chloride ,Pineal Gland ,Pinealocyte ,Potassium Chloride ,Potassium Channels, Calcium-Activated ,Extracellular ,Animals ,Large-Conductance Calcium-Activated Potassium Channels ,Membrane potential ,Chemistry ,Depolarization ,Potassium channel ,Acetylcholine ,Rats ,Electrophysiology ,Nicotinic agonist ,Biochemistry ,Microscopy, Fluorescence ,Biophysics ,Calcium ,Calcium Channels ,Intracellular ,Research Article - Abstract
1. Membrane voltage (Vm) recordings were obtained from isolated rat pinealocytes using the patch-clamp technique. In parallel to the electrophysiological experiments, intracellular Ca2+ measurements were performed using fura-2. 2. The resting Vm averaged -43 mV and replacement of extracellular NaCl by KCl completely depolarized the cells. This indicates that the resting Vm is dominated by a K+ conductance. Single-channel recordings revealed the presence of a large conductance Ca(2+)-activated charybdotoxin-sensitive K+ channel. 3. Application of ACh (100 microM) depolarized the pinealocytes on average by 16 mV. The depolarizing effect of ACh was mimicked by nicotine (50 microM) and was prevented by tubocurarine (100 microM). 4. The ACh-induced depolarization was largely abolished in the absence of extracellular Na+, but was not significantly affected by extracellular Ca2+ removal. 5. Application of ACh (100 microM) caused an increase in [Ca2+]i. This increase was completely dependent on the presence of extracellular Ca2+ and was largely reduced after extracellular Na+ removal. Nifedipine (1 microM) reduced the ACh-induced increase in [Ca2+]i by about 50%. 6. Our findings indicate that in rat pinealocytes stimulation of a nicotinic ACh receptor (nAChR) induces depolarization mainly by Na+ influx via the nAChR. The depolarization then activates L-type Ca2+ channels, which are responsible for the nifedipine-sensitive portion of the intracellular Ca2+ increase. Ca2+ influx via the nAChR probably also contributes to the observed rise in [Ca2+]i.
- Published
- 1997
46. Noradrenergic and VIPergic Signal Transduction in Rat Pinealocytes
- Author
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Horst-Werner Korf and Christof Schomerus
- Subjects
biology ,Vasoactive intestinal peptide receptor ,Vasoactive intestinal peptide ,chemistry.chemical_element ,Calcium ,CREB ,Calcium in biology ,Cell biology ,Pinealocyte ,Pineal gland ,medicine.anatomical_structure ,chemistry ,biology.protein ,medicine ,Receptor - Abstract
In the present study we investigated the effects of norepinephrine and vasoactive intestinal peptide on the intracellular calcium concentration ([Ca2+]i) and on phosphorylation of the transcription factor CREB in isolated rat pinealocytes. Norepinephrine evoked a biphasic calcium response via activation of α1-adrenergic receptors in virtually all pinealocytes identified by the S-antigen immunoreaction. This response involved mobilization of calcium from intracellular calcium stores and calcium influx into the cell. Moreover, norepinephrine induced phosphorylation of CREB via activation of β-adrenergic receptors. In contrast, vasoactive intestinal peptide did not cause an elevation of [Ca2+]i, but induced pCREB immunoreactivity in a subpopulation of the pinealocytes, suggesting their functional heterogeneity.
- Published
- 1997
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47. Signal transduction molecules in the rat pineal organ: Ca2+, pCREB, and ICER
- Author
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Erik Maronde, Christof Schomerus, Horst-W. Korf, and Jörg H. Stehle
- Subjects
endocrine system ,Models, Neurological ,CREB ,Pineal Gland ,Second Messenger Systems ,Pinealocyte ,Melatonin ,Cyclic AMP Response Element Modulator ,medicine ,Cyclic AMP ,Animals ,Cyclic AMP Response Element-Binding Protein ,Transcription factor ,Ecology, Evolution, Behavior and Systematics ,biology ,Chemistry ,General Medicine ,Cell biology ,Rats ,DNA-Binding Proteins ,Repressor Proteins ,Hes3 signaling axis ,Second messenger system ,biology.protein ,Calcium ,Signal transduction ,Transduction (physiology) ,medicine.drug ,Signal Transduction ,Transcription Factors - Abstract
The mammalian pineal organ transduces light-dependent neural inputs into a hormonal output. This photoneuroendocrine transduction results in a largely elevated concentration of the pineal hormone melatonin at night. The rhythm in melatonin production and secretion depends on activation and inactivation of transcriptional, translational, and posttranslational mechanisms fundamentally linked to two second messenger systems, the cAMP- and the Ca(2+)-signal transduction pathways. Here we review molecular biological, immunocytochemical, and single-cell imaging studies, which demonstrate a time- and substance-specific activation of these signaling pathways in rat pinealocytes. The data provide a framework for understanding the complex interactions between second messengers (cAMP, Ca2+), transcription factors (CREB, ICER), and their role in regulation of melatonin synthesis. The data have proven the rat pinealocyte to be an interesting model to study transmembrane signaling pathways which may be common to both neuroendocrine and neuronal cells.
- Published
- 1996
48. Vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP) induce phosphorylation of the transcription factor CREB in subpopulations of rat pinealocytes: immunocytochemical and immunochemical evidence
- Author
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Elke Laedtke, Horst-Werner Korf, Erik Maronde, and Christof Schomerus
- Subjects
Male ,medicine.medical_specialty ,Histology ,Vasoactive intestinal peptide ,Immunoblotting ,Neuropeptide ,Adenylate kinase ,Stimulation ,Biology ,CREB ,Pineal Gland ,Pathology and Forensic Medicine ,Pinealocyte ,Immunoenzyme Techniques ,chemistry.chemical_compound ,Norepinephrine ,Internal medicine ,medicine ,Cyclic AMP Response Element-Binding Protein ,Animals ,Phosphorylation ,Rats, Wistar ,Cells, Cultured ,Neurotransmitter Agents ,Forskolin ,Neuropeptides ,Cell Biology ,Rats ,Endocrinology ,chemistry ,biology.protein ,Pituitary Adenylate Cyclase-Activating Polypeptide ,hormones, hormone substitutes, and hormone antagonists ,Vasoactive Intestinal Peptide - Abstract
We investigated whether vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP), which stimulate melatonin biosynthesis in the mammalian pineal organ, cause phosphorylation of the cyclic AMP response element binding protein (CREB) in rat pinealocytes. Dispersed cells were treated with varying concentrations of VIP and PACAP for 10 to up to 240 min and then immunocytochemically analyzed with an antibody against phosphorylated CREB (pCREB). The experiments showed a dose- and time-dependent induction of pCREB immunoreactivity in the nuclei of subpopulations of pinealocytes identified by the S-antigen immunoreaction. Stimulation with VIP elicited pCREB immunoreaction in approximately 50–65% of the S-antigen immunoreactive pinealocytes. The number of PACAP-responsive pinealocytes was often smaller and more variable. Maximal responses to both neuropeptides were seen after 30 min. pCREB immunoreaction gradually declined within 2 h and could not be induced again by an additional stimulation. In contrast, norepinephrine (NE) elicited pCREB immunoreaction in more than 95% of the pinealocytes, and this response lasted as long as 300 min. Treatment of pinealocytes with forskolin or KCl induced pCREB immunoreaction in the vast majority of pinealocytes, showing that in principle elevation of the intracellular concentrations of both cAMP and calcium can cause the response. Immunoblotting analyses confirmed that the immunoreaction elicited by VIP, PACAP and NE is largely due to phosphorylation of a 42-kDa protein corresponding to CREB, but reflects to a minor extent also phosphorylation of two smaller proteins presumably related to ATF-1. Immunocytochemical and immunochemical investigations with an antibody against total CREB showed that stimulation with VIP, PACAP and NE did not affect the level of CREB. All findings indicate that the stimulatory effects of VIP and PACAP on rat pinealocytes involve phosphorylation of transcription factors of the CREB family as holds also true for NE. However, VIP and PACAP affected only subpopulations of pinealocytes and the reponses lasted for a shorter period of time than those to NE. This conforms to previous results showing that both neuropeptides are also less effective than NE in stimulating the melatonin biosynthesis in the rat pineal organ.
- Published
- 1996
49. Calcium responses of isolated, immunocytochemically identified rat pinealocytes to noradrenergic, cholinergic and vasopressinergic stimulations
- Author
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Elke Laedtke, Christof Schomerus, and Horst-Werner Korf
- Subjects
medicine.medical_specialty ,chemistry.chemical_element ,Biology ,Calcium ,Cholinergic Agonists ,In Vitro Techniques ,Pineal Gland ,Calcium in biology ,Cholinergic Antagonists ,Pinealocyte ,Cellular and Molecular Neuroscience ,Pineal gland ,Nerve Fibers ,Internal medicine ,medicine ,Animals ,Rats, Wistar ,Calcium signaling ,T-type calcium channel ,Rats, Inbred Strains ,Cell Biology ,Immunohistochemistry ,Stimulation, Chemical ,Rats ,Arginine Vasopressin ,medicine.anatomical_structure ,Endocrinology ,chemistry ,Cholinergic ,Seasons ,Acetylcholine ,medicine.drug - Abstract
Calcium responses of isolated rat pineal cells to noradrenergic, cholinergic and vasopressinergic stimulations were recorded by use of the fura-2 technique and an image analysis system. Subsequently the recorded cells were identified as pinealocytes by immunocytochemical demonstration of S-antigen, a pinealocyte-specific marker. S-antigen immunoreactive pinealocytes were shown to respond to norepinephrine stimulation with an elevation of the intracellular free calcium concentration ([Ca2+]i). This response was dose-dependent and consisted of a rapid increase in [Ca2+]i (primary phase) followed by a decrease to an elevated plateau well above the basal level (secondary phase). The plateau persisted for at least 1 h when cells were constantly exposed to norepinephrine and dropped to basal level upon removal of the stimulus. Analysis of the calcium responses of cells treated with caffeine or thapsigargin suggested that the primary phase reflects mobilization of calcium from inositol 1,4,5-trisphosphate-sensitive intracellular calcium stores. Depletion of these calcium stores was a decisive and sufficient prerequisite to evoke the secondary phase which was apparently elicited by calcium influx. These data suggest that a capacitative calcium entry is involved in pineal calcium signalling. Acetylcholine induced an increase in [Ca2+]i in rat pinealocytes. Experiments with different cholinergic agonists and antagonists provided evidence that the acetylcholine-induced calcium response was mediated via nicotinic acetylcholine receptors. Stimulation of isolated rat pineal cells with arginine-vasopressin caused a rise in [Ca2+]i in approx. 5% of the cells. However, these cells remained unidentified because they contained neither immunoreactive S-antigen nor immunoreactive glial fibrillary acidic protein, a marker for interstitial (glial) cells of the rat pineal organ. Taken together, the results underline the pivotal role of norepinephrine for the regulation of pineal signal transduction, but they also support the notion that other neurotransmitters and neuropeptides are involved in the modulation of pineal calcium signalling.
- Published
- 1995
50. Subject Index Vol. 6, 1997
- Author
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Michikazu Samejima, Ken-ichi Honma, Norio Suzuki, Stuart E. Dryer, Akihito Adachi, T. Yamauchi, Ritsuko Ohtani-Kaneko, T. Suzuki, Satoko Hashimoto, Katsumi Aida, Susanne Kroeber, Gregory M. Cahill, H. Kudou, S. Kajihara, V.M. Cassone, Yutaka Ohashi, B. Pitrosky, P. Greve, M. Kurushima, Katsuhisa Uchida, Masayuki Hara, Masaomi Iyo, S. Hashimoto, M.F. Xu, Takuro Endo, Theresa D'Souza, Y. Saito, Jiri Vanecek, Takashi Yoshimura, D.J. Kennaway, P.L. Tang, P. Pévet, Yukitomo Morita, Masayuki Iigo, Norio Okamoto, Sato Honma, Norio Mori, G. Takahashi, N. Kimura, P.M. Iuvone, T. Kachi, A. Alonso-Gomez, Takuya Nogi, Minoru Hasegawa, Z.M. Qian, D.C. Klein, Kazuaki Hirata, Hana Zemkova, M. Bernard, Kanjun Hirunagi, Satoshi Tamotsu, Christof Schomerus, Mitsuo Tabata, Horst-W. Korf, Shizufumi Ebihara, Ondrej Slanar, T. Irie, and K. Honma
- Subjects
Cellular and Molecular Neuroscience ,Index (economics) ,Developmental Neuroscience ,Neurology ,Statistics ,Subject (documents) ,Mathematics - Published
- 1997
- Full Text
- View/download PDF
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