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The neuroendocrine system consists of a heterogeneous collection of (mostly) neuropeptidergic neurons found in four hypothalamic nuclei and sharing the ability to secrete neurohormones (all of them neuropeptides except dopamine) into the bloodstream. There are, however, abundant hypothalamic non-neuroendocrine neuropeptidergic neurons developing in parallel with the neuroendocrine system, so that both cannot be entirely disentangled. This heterogeneity results from the workings of a network of transcription factors many of which are already known. Olig2 and Fezf2 expressed in the progenitors, acting through mantle-expressed Otp and Sim1, Sim2 and Pou3f2 (Brn2), regulate production of magnocellular and anterior parvocellular neurons. Nkx2-1, Rax, Ascl1, Neurog3 and Dbx1 expressed in the progenitors, acting through mantle-expressed Isl1, Dlx1, Gsx1, Bsx, Hmx2/3, Ikzf1, Nr5a2 (LH-1) and Nr5a1 (SF-1) are responsible for tuberal parvocellular (arcuate nucleus) and other neuropeptidergic neurons. The existence of multiple progenitor domains whose progeny undergoes intricate tangential migrations as one source of complexity in the neuropeptidergic hypothalamus is the focus of much attention. How neurosecretory cells target axons to the medial eminence and posterior hypophysis is gradually becoming clear and exciting progress has been made on the mechanisms underlying neurovascular interface formation. While rat neuroanatomy and targeted mutations in mice have yielded fundamental knowledge about the neuroendocrine system in mammals, experiments on chick and zebrafish are providing key information about cellular and molecular mechanisms. Looking forward, data from every source will be necessary to unravel the ways in which the environment affects neuroendocrine development with consequences for adult health and disease. [ABSTRACT FROM AUTHOR]

The aim of the present article is to analyse the evolutionary links between protozoa and neuronal and neurosecretory cells. To this effect we employ functional and topological data available for ciliates, in particular for Paramecium . Of note, much less data are available for choanoflagellates, the progenitors of metazoans, which currently are in the focus of metazoan genomic data mining. Key molecular players are found from the base to the highest levels of eukaryote evolution, including neurones and neurosecretory cells. Several common fundamental mechanisms, such as SNARE proteins and assembly of exocytosis sites, GTPases, Ca 2+ -sensors, voltage-gated Ca 2+ -influx channels and their inhibition by the forming Ca 2+ /calmodulin complex are conserved, albeit with different subcellular channel localisation, from protozoans to man. Similarly, Ca 2+ -release channels represented by InsP 3 receptors and putative precursors of ryanodine receptors, which all emerged in protozoa, serve for focal intracellular Ca 2+ signalling from ciliates to mammalian neuronal cells, eventually in conjunction with store-operated Ca 2+ -influx. Restriction of Ca 2+ signals by high capacity/low affinity Ca 2+ -binding proteins is maintained throughout the evolutionary tree although the proteins involved differ between the taxa. Phosphatase 2B/calcineurin appears to be involved in signalling and in membrane recycling throughout evolution. Most impressive example of evolutionary conservation is the sub-second dynamics of exocytosis-endocytosis coupling in Paramecium cells, with similar kinetics in neuronal and neurosecretory systems. Numerous cell surface receptors and channels that emerge in protozoa operate in the human nervous system, whereas a variety of cell adhesion molecules are newly “invented” during evolution, enabled by an increase in gene numbers, alternative splice forms and transcription factors. Thereby, important regulatory and signalling molecules are retained as a protozoan heritage. [ABSTRACT FROM AUTHOR]

Abstract The current study is the first one, at least, in Mosul University, and perhaps, in other universities in Iraq, being a new topic, the sinus gland. Furthermore, an original and successful method was found and used to overcome an old and difficult problem regarding the sectioning of the eyestalks which are covered by a thick, hard and calcified cuticle that causes destruction of the sections. Five histological and nine histochemical staining techniques were employed. The results have clearly shown the presence of only one sinus gland in each eyestalk. It is an elongated ellipsoid structure, dorsoventral in position and composed of four principal elements, the capsule, axon terminals, stromal tissues, and blood sinuses and vessels. Four patterns of neurosecretory granules were distinguished and classified according to certain basic criteria.

Nervous and neuroendocrine systems mediate environmental conditions to control a variety of life history traits. Our goal was to provide mechanistic insights as to how neurosecretory signals mediate division of labor in the honey bee (Apis mellifera). Worker division of labor is based on a process of behavioral maturation by individual bees, which involves performing in-hive tasks early in adulthood, then transitioning to foraging for food outside the hive. Social and nutritional cues converge on endocrine factors to regulate behavioral maturation, but whether neurosecretory systems are central to this process is not known. To explore this, we performed transcriptomic profiling of a neurosecretory region of the brain, the pars intercerebralis (PI). We first compared PI transcriptional profiles for bees performing in-hive tasks and bees engaged in foraging. Using these results as a baseline, we then performed manipulative experiments to test whether the PI is responsive to dietary changes and/or changes in juvenile hormone (JH) levels. Results reveal a robust molecular signature of behavioral maturation in the PI, with a subset of gene expression changes consistent with changes elicited by JH treatment. In contrast, dietary changes did not induce transcriptomic changes in the PI consistent with behavioral maturation or JH treatment. Based on these results, we propose a new verbal model of the regulation of division of labor in honey bees in which the relationship between diet and nutritional physiology is attenuated, and in its place is a relationship between social signals and nutritional physiology that is mediated by JH. [ABSTRACT FROM AUTHOR]

RE-1 silencing transcription factor (REST), a master negative regulator of neuronal differentiation, controls neurogenesis by preventing the differentiation of neural stem cells. Here we focused on the role of REST in the early steps of differentiation and maturation of adult hippocampal progenitors (AHPs). REST knockdown promoted differentiation and affected the maturation of rat AHPs. Surprisingly, REST knockdown cells enhanced the differentiation of neighboring wild-type AHPs, suggesting that REST may play a non–cellautonomous role. Gene expression analysis identified Secretogranin II (Scg2) as the major secreted REST target responsible for the non–cell-autonomous phenotype. Loss-of-function of Scg2 inhibited differentiation in vitro, and exogenous SCG2 partially rescued this phenotype. Knockdown of REST in neural progenitors in mice led to precocious maturation into neurons at the expense of mushroom spines in vivo. In summary, we found that, in addition to its cell-autonomous function, REST regulates differentiation and maturation of AHPs non–cell-autonomously via SCG2. [ABSTRACT FROM AUTHOR]

Extraretinal photoreceptors located within the medio-basal hypothalamus regulate the photoperiodic control of seasonal reproduction in birds. An action spectrum for this response describes an opsin photopigment with a λ max of ∼492 nm. Beyond this however, the specific identity of the photopigment remains unresolved. Several candidates have emerged including rod-opsin; melanopsin (OPN4); neuropsin (OPN5); and vertebrate ancient (VA) opsin. These contenders are evaluated against key criteria used routinely in photobiology to link orphan photopigments to specific biological responses. To date, only VA opsin can easily satisfy all criteria and we propose that this photopigment represents the prime candidate for encoding daylength and driving seasonal breeding in birds. We also show that VA opsin is co-expressed with both gonadotropin-releasing hormone (GnRH) and arginine-vasotocin (AVT) neurons. These new data suggest that GnRH and AVT neurosecretory pathways are endogenously photosensitive and that our current understanding of how these systems are regulated will require substantial revision. [ABSTRACT FROM AUTHOR]

We present a model to explain how the neurosecretory system of aquatic mollusks generates their diversity of shell structures and pigmentation patterns. The anatomical and physiological basis of this model sets it apart from other models used to explain shape and pattern. The model reproduces most known shell shapes and patterns and accurately predicts how the pattern alters in response to environmental disruption and subsequent repair. Finally, we connect the model to a larger class of neural models. [ABSTRACT FROM AUTHOR]

Stomatogastric musculature from crabs in the genus Cancer provides a system in which modulatory roles of peptides from the FLRFamide family can be compared. The anterior cardiac plexus (ACP) is a neuroendocrine release site within the Cancer stomatogastric nervous system that is structurally identical in C. borealis, C. productus, and C. magister but that appears to contain FLRFamide-like peptide(s) only in C. productus. We measured the effect of TNRNFLRFamide on nerve-evoked contractions of muscles that were nearby, an intermediate distance, or far from the ACP. We found the spatial pattern of FLRFamidergic modulation of muscles in C. productus to be qualitatively different than in C. borealis or C. magister. In C. productus, muscles proximal to the ACP were more responsive than distal muscles. In C. borealis, FLRFamidergic response was less dependent on muscle location. These results suggest that functionally different roles of FLRFamides in modulating stomatogastric muscle movements may have evolved in different Cancer species. [ABSTRACT FROM AUTHOR]

In the moth, Manduca sexta, the neuropeptide, eclosion hormone, triggers a dramatic rise in the levels of intracellular cGMP within a group of 50 neurons. The cells within this group include the segmentally repeated neurosecretory cell, Cell 27. In this study the effect of cGMP on the excitability of Cell 27 was investigated using intracellular recordings. Prior to its normal elevation in cGMP, Cell 27 exhibited a high spike threshold, but this was lowered dramatically when intracellular cGMP levels increased. The latter was also associated with spontaneous action potentials. This change in excitability did not correspond with changes in either resting potential, input resistance, or action potential amplitude. A similar lowering of threshold was induced by perfusion of 8-bromo-cGMP, whereas 8-bromo-cAMP caused the threshold to increase. Intracellular recordings using various ion substitution paradigms and channel blockers provided evidence which suggests indirectly that Ca2+ is mostly responsible for the depolarizing phase of the action potential while a Ca2+-activated K+ current contributes to the hyperpolarization. The results of these manipulations are consistent with the hypothesis that cGMP may partially increase excitability in Cell 27 by enhancing an inward Ca2+ current. [ABSTRACT FROM AUTHOR]

The ultrastructural characteristics of the arcuate nucleus and median eminence in rats have been studied by means of formaldehyde-osmium tetroxide fixation method. The observations showed that there are two kinds of neurons (dark and light) in the arcuate nucleus which might be responsible for producing both dopamine and releasing hormones. The tanycytes of the ependyma of the third cerebral ventricle pass longitudinally through the various zones of the median eminence and reach at pericapillary space of the portal vessels. The neurosecretory substance-containing nerve terminals may travel between ependymal cells and even enter the cavity of the third ventricle or end around the basal membrane of the capillaries of the median eminence. The axo-somatic and axodendritic synapses are formed at the perikaryon and dendrites of neurons in the arcuate nucleus. Both agranular type and granular type of axo-axonic synapses are encountered in the fibrous zone of the median eminence. There are also synaptic connections between the basic processes of tanycytes and the large granular vesicle-containing nerve terminals in the palisade zone of the median eminence. The ultrastructural characteristics mentioned above suggest that (1) the releasing (or inhibiting) hormones of the hypothalamus might be released through two routes: into the portal capillaries from nerve terminals directly or into the cerebrospinal fluid of the third ventricle first and uptaken by tanycytes, then transported to the portal capillaries by the basic processes of tanycyte; (2) each step of synthesis, storage, transport and release of the releasing (or inhibiting) hormones could be regulated by nervous mechanism. [ABSTRACT FROM AUTHOR]

The presence and distribution of bombesin-like material were investigated in the brain of the cartilaginous fish Scyliorhinus canicula using conventional immunocytochemical techniques. Perikarya containing bombesin-like immunoreactivity were identified in the hypothalamus, within the magnocellular component of the preoptic nucleus. Some immunopositive elements appeared to be of cerebrospinal fluid-contacting type. Beaded immunoreactive fibers were seen crossing the ventral telencephalon and the whole hypothalamus. An important tract of fibers was found in the infundibular floor and in the median eminence, in close contact with the vascular system of the pituitary portal plexus. A moderate number of positive fibers innervated the habenular complex and the dorsal wall of the posterior tuberculum. These findings indicate that a neuropeptide strictly related to amphibian bombesin is located in specific hypothalamic neurons of S. canicula. The distribution of the immunoreactive fibers and terminals suggests that, in fish, this peptide, may be involved in neuroendocrine and neuromodulator functions. [ABSTRACT FROM AUTHOR]

RE-1 silencing transcription factor (REST), a master negative regulator of neuronal differentiation, controls neurogenesis by preventing the differentiation of neural stem cells. Here we focused on the role of REST in the early steps of differentiation and maturation of adult hippocampal progenitors (AHPs). REST knockdown promoted differentiation and affected the maturation of rat AHPs. Surprisingly, REST knockdown cells enhanced the differentiation of neighboring wild-type AHPs, suggesting that REST may play a non-cell-autonomous role. Gene expression analysis identified Secretogranin II (Scg2) as the major secreted REST target responsible for the non-cell-autonomous phenotype. Loss-of-function of Scg2 inhibited differentiation in vitro, and exogenous SCG2 partially rescued this phenotype. Knockdown of REST in neural progenitors in mice led to precocious maturation into neurons at the expense of mushroom spines in vivo. In summary, we found that, in addition to its cell-autonomous function, REST regulates differentiation and maturation of AHPs non-cell-autonomously via SCG2., Significance Statement: Our results reveal that REST regulates differentiation and maturation of neural progenitor cells in vitro by orchestrating both cell-intrinsic and non-cell-autonomous factors and that Scg2 is a major secretory target of REST with a differentiation-enhancing activity in a paracrine manner. In vivo, REST depletion causes accelerated differentiation of newborn neurons at the expense of spine defects, suggesting a potential role for REST in the timing of the maturation of granule neurons., (Copyright © 2015 the authors 0270-6474/15/3514872-13$15.00/0.)

The hypothalamus is a part of the brain that is critical for sustaining life through its homeostatic control and integrative regulation of the autonomic nervous system and neuroendocrine systems. Neuroendocrine function in mammals is mediated mainly through the control of pituitary hormone secretion by diverse neuroendocrine cell groups in the hypothalamus. Cannabinoid receptors are expressed throughout the hypothalamus, and endocannabinoids have been found to exert pronounced regulatory effects on neuroendocrine function via modulation of the outputs of several neuroendocrine systems. Here, we review the physiological regulation of neuroendocrine function by endocannabinoids, focusing on the role of endocannabinoids in the neuroendocrine regulation of the stress response, food intake, fluid homeostasis, and reproductive function. Cannabis sativa (marijuana) has a long history of recreational and/or medicinal use dating back to ancient times. It was used as an analgesic, anesthetic, and antianxiety herb as early as 2600 B.C. The hedonic, anxiolytic, and mood-elevating properties of cannabis have also been cited in ancient records from different cultures. However, it was not until 1964 that the psychoactive constituent of cannabis, Δ(9)-tetrahydrocannabinol, was isolated and its chemical structure determined (Gaoni & Mechoulam, 1964)., (© 2015 Elsevier Inc. All rights reserved.)