180 results on '"Pituitary gonadotropin"'
Search Results
2. Reproductive Endocrinology of the European Eel, Anguilla anguilla
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Dufour, Sylvie, Burzawa-Gerard, Elisabeth, Le Belle, Nadine, Sbaihi, Miskal, Vidal, Bernadette, Aida, Katsumi, editor, Tsukamoto, Katsumi, editor, and Yamauchi, Kohei, editor
- Published
- 2003
- Full Text
- View/download PDF
3. The Role of Activin in Spermatogenesis in Fish
- Author
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Nagahama, Yoshitaka, Miura, Takeshi, Kobayashi, Tohru, Ding, Jun, Aono, Toshihiro, editor, Sugino, Hiromu, editor, and Vale, Wylie W., editor
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- 1997
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4. Ovulation and Stress: Pathophysiology
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Genazzani, A. R., Petraglia, F., Monzani, A., Fabbri, G., Genazzani, A. D., Di Domenica, P., Volpe, A., Mashiach, Shlomo, editor, Ben-Rafael, Zion, editor, Laufer, Neri, editor, and Schenker, Joseph G., editor
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- 1990
- Full Text
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5. Kisspeptin in the early post-partum of the dairy cow
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Raffaele Luigi Sciorsci, Edmondo Ceci, Annalisa Rizzo, and Antonio Ciro Guaricci
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Ovulation ,Period (gene) ,Ice calving ,Biology ,Gonadotropin-Releasing Hormone ,Andrology ,03 medical and health sciences ,0302 clinical medicine ,Endocrinology ,Kisspeptin ,Blood concentration ,Follicular phase ,Animals ,Progesterone ,Post partum ,Kisspeptins ,030219 obstetrics & reproductive medicine ,Postpartum Period ,Pituitary gonadotropin ,0402 animal and dairy science ,Estrogens ,04 agricultural and veterinary sciences ,Luteinizing Hormone ,040201 dairy & animal science ,Pituitary Gland ,Cattle ,Female ,Animal Science and Zoology ,Follicle Stimulating Hormone ,Biotechnology - Abstract
Recently, a new molecule, kisspeptin (Kp), and in particular Kisspeptin 10 (Kp10), was implicated in stimulating the hypothalamic-pituitary-gonadal axis. The aim of this study was to evaluate circulating Kp10 levels in the early post-partum period of the dairy cow. Blood samples were collected from 40 dairy cows, at 10 (T10), 12 (T12), 14 (T14) and 16 (T16) days after calving. Progesterone (P4) levels were evaluated using ELISA, and levels of oestrogens (E2) and Kp were evaluated using a radio-immunologic method. After an initial plateau, Kp10 significantly increased at T14 and decreased at T16. The P4 and E2 mean serum values remained in the physiological range. It is likely that Kp10 enhanced hypothalamic GnRH release as well as pituitary gonadotropin secretion, thus promoting follicular growth and the increase in E2 levels, which might have further enhanced Kp10 release through a positive feedback loop. To our best knowledge, this is the first report on the range of Kp10 blood concentration during the early post-partum period in the dairy cow. The results of our study will increase our current understanding of the complex neuro-endocrine crosstalk underlying the resumption of ovarian cyclicity in the dairy cow.
- Published
- 2018
6. Advances in computational modeling approaches of pituitary gonadotropin signaling
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Eric Reiter, Anne Poupon, Romain Yvinec, Pascale Crépieux, Frédérique Clément, Physiologie de la reproduction et des comportements [Nouzilly] (PRC), Centre National de la Recherche Scientifique (CNRS)-Université de Tours-Institut Français du Cheval et de l'Equitation [Saumur]-Institut National de la Recherche Agronomique (INRA), Mathematical and Mechanical Modeling with Data Interaction in Simulations for Medicine (M3DISIM), Laboratoire de mécanique des solides (LMS), École polytechnique (X)-MINES ParisTech - École nationale supérieure des mines de Paris-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-MINES ParisTech - École nationale supérieure des mines de Paris-Centre National de la Recherche Scientifique (CNRS)-Inria Saclay - Ile de France, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria), Institut National de la Recherche Agronomique (INRA)-Institut Français du Cheval et de l'Equitation [Saumur]-Université de Tours-Centre National de la Recherche Scientifique (CNRS), École polytechnique (X)-MINES ParisTech - École nationale supérieure des mines de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-MINES ParisTech - École nationale supérieure des mines de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Inria Saclay - Ile de France, Institut National de la Recherche Agronomique (INRA)-Institut Français du Cheval et de l'Equitation [Saumur] (IFCE)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), École polytechnique (X)-Mines Paris - PSL (École nationale supérieure des mines de Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Mines Paris - PSL (École nationale supérieure des mines de Paris), Institut National de la Recherche Agronomique (INRA)-Institut Français du Cheval et de l'Equitation [Saumur]-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-MINES ParisTech - École nationale supérieure des mines de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS)-MINES ParisTech - École nationale supérieure des mines de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École polytechnique (X)-Inria Saclay - Ile de France, and Yvinec, Romain
- Subjects
LH ,0301 basic medicine ,Hypothalamo-Hypophyseal System ,endocrine system ,Molecular Networks (q-bio.MN) ,Systems biology ,030209 endocrinology & metabolism ,multi-scale modeling ,Biology ,hormone rhythms ,Receptors, G-Protein-Coupled ,[SDV.BDLR.RS]Life Sciences [q-bio]/Reproductive Biology/Sexual reproduction ,GPCR Signaling ,03 medical and health sciences ,0302 clinical medicine ,systems biology ,GPCR signaling ,FSH ,Cell Behavior (q-bio.CB) ,Drug Discovery ,Animals ,Humans ,Quantitative Biology - Molecular Networks ,Computer Simulation ,Gonadotropins pituitary ,GnRH ,mathematical models ,Reproduction ,Systems Biology ,Pituitary gonadotropin ,Models, Theoretical ,[SDV.BIBS]Life Sciences [q-bio]/Quantitative Methods [q-bio.QM] ,3. Good health ,030104 developmental biology ,FOS: Biological sciences ,Gonadotropins, Pituitary ,Quantitative Biology - Cell Behavior ,Neuroscience ,Signal Transduction - Abstract
Pituitary gonadotropins play an essential and pivotal role in the control of human and animal reproduction within the hypothalamic-pituitary-gonadal (HPG) axis. The computational modeling of pituitary gonadotropin signaling encompasses phenomena of different natures such as the dynamic encoding of gonadotropin secretion, and the intracellular cascades triggered by gonadotropin binding to their cognate receptors, resulting in a variety of biological outcomes. We overview historical and ongoing issues in modeling and data analysis related to gonadotropin secretion in the field of both physiology and neuro-endocrinology. We mention the different mathematical formalisms involved, their interest and limits. We discuss open statistical questions in signal analysis associated with key endocrine issues. We also review recent advances in the modeling of the intracellular pathways activated by gonadotropins, which yields promising development for innovative approaches in drug discovery. The greatest challenge to be tackled in computational modeling of pituitary gonadotropin signaling is the embedding of gonadotropin signaling within its natural multi-scale environment, from the single cell level, to the organic and whole HPG level. The development of modeling approaches of G protein-coupled receptor signaling, together with multicellular systems biology may lead to unexampled mechanistic understanding with critical expected fallouts in the therapeutic management of reproduction., Comment: in press
- Published
- 2018
7. Effect of Tiangui recipe on serum leptin and pituitary gonadotropin in androgen-sterilized ratson serum leptin and pituitary gonadotropin in androgen-sterilized rats.
- Author
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Sun, Fei and Yu, Jin
- Abstract
Objective: To explore the effect of Tiangui Recipe (TGR) on obesity and reproductive function in androgen-sterilized rats (ASR). Methods: ASR model was established by subcutaneous injection of testosterone propionate to SD female rats at the age of 9 days. Change of serum leptin, follicular stimulating hormone (FSH) and luteinizing hormone (LH) in model rats aged 115 days before and after feeding them with TGR was measured by radioimmunoassay (RIA). Meanwhile, criteria of energy state, including diurnal food intake, retroperitoneal fat depot weight and body weight, were measured and evaluated. Results: ASR had the characteristics of high metabolic rate, energy imbalance and obesity. Serum level of leptin increased and FSH, LH decreased significantly (P<0.01) in model rats as compared with the normal rats. Significant positive correlation between leptin level and body weight (r=0.8977, P<0.001) was observed, and negative correlation was seen between FSH, LH and leptin (r = -0.7517, P<0.001; r= -0.8444, P<0.001, respectively). The endocrine changes of ASR all returned to normal range after the TGR treatment. Conclusion: Obesity and concerned hypogonadotrophic hypogonadal anovulation were expressed in ASR. TGR may play an important role in reducing weight and inducing ovulation. [ABSTRACT FROM AUTHOR]
- Published
- 2000
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8. After 65 Years, Research Is Still Fun
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William Hansel
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Estrous cycle ,Gynecology ,endocrine system ,medicine.medical_specialty ,Biomedical Research ,In vitro fertilisation ,Reproductive Physiological Phenomena ,General Veterinary ,Animal Nutrition Sciences ,medicine.medical_treatment ,Pituitary gonadotropin ,Physiology ,History, 20th Century ,Biology ,History, 21st Century ,United States ,medicine.anatomical_structure ,Genetics ,medicine ,Animals ,Animal Nutritional Physiological Phenomena ,Animal Science and Zoology ,Corpus luteum ,Biotechnology - Abstract
In 1946, at the end of World War II, I entered graduate school at Cornell University, where I remained for 44 years. During that time, my laboratory produced more than 300 publications in the field of reproductive biology, including studies on nutrition and reproduction, the role of the hypothalamus in pituitary gonadotropin release, corpus luteum formation and function, hormone assays, and estrous cycle synchronization. At age seventy, I retired from Cornell and accepted the Gordon Cain Endowed Professorship at Louisiana State University, where I continued my work on the bovine corpus luteum and added research on the collection, maturation, in vitro fertilization, and culture of bovine oocytes. In 1994, I moved to the Pennington Biomedical Research Center and soon thereafter started the research that led to development of the lytic peptide–gonadotropin conjugates, which target and destroy cancer cell membranes. I am continuing my work on the development of targeted cancer cell drugs and, yes, research is still fun!
- Published
- 2013
9. Pituitary-Ovarian Function in IUD Users
- Author
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Abdalla, M. I., Ibrahim, I. I., Osman, M. I., Bayad, M. A., Hafez, E. S. E., editor, and Van Os, W. A. A., editor
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- 1980
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10. How does the Gonad Affect LHRH Secretion? Effects of Gonadectomy on LHRH Release from Median Eminence Nerve Terminals Incubated In Vitro and on LHRH Concentration in Hypophyseal Portal Blood
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Valenca, M. M., Ching, M., Masotto, C., Negro-Vilar, A., Mahesh, Virendra B., editor, Dhindsa, Dharam S., editor, Anderson, Everett, editor, and Kalra, Satya P., editor
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- 1987
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11. Strategies for the Inhibition of Gonadotropin Action
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Sairam, M. R., McKerns, Kenneth W., editor, and Naor, Zvi, editor
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- 1984
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12. Hormonal Regulation of Pituitary Gonadotropin Gene Expression
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Chin, William W., Gharib, Soheyla D., Wierman, Margaret E., and Talwar, G. P., editor
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- 1988
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13. Granulosa Cell Tumor, Ovary, Mouse
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Alison, Roger H., Morgan, Kevin T., Jones, Thomas Carlyle, editor, Mohr, Ulrich, editor, and Hunt, Ronald Duncan, editor
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- 1987
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14. Recent Advances in the Study of the Hypothalamic Releasing Factors
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Martini, L., Knowles, Francis, editor, and Vollrath, Lutz, editor
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- 1974
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15. Hormone Assays
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Keller, Paul J. and Keller, Paul J.
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- 1981
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16. Treatment of Postmenopausal Women with Breast Cancer with Gonadotropin-Releasing Hormone Analogues
- Author
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Waxman, J. and Höffken, Klaus, editor
- Published
- 1988
- Full Text
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17. Effects of Passi/Zora /oetida Linn. (Passifloraceae) on Genital Tract, Serum Estradiol, Pituitary Gonadotropin and Prolactin Level in Female Adult and Immature Ovariectomized Rats
- Author
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Toure Alassane, Kouakou Koffi, Traore Flavien, and Bleu Gome Michel
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medicine.medical_specialty ,Endocrinology ,biology ,Passifloraceae ,Genital tract ,Internal medicine ,Serum estradiol ,Pituitary gonadotropin ,medicine ,Ovariectomized rat ,Prolactin level ,General Agricultural and Biological Sciences ,biology.organism_classification - Published
- 2012
18. 17,20β,21-Trihydroxy-4-pregnen-3-one
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Taisen Iguchi, Yukiko Ogino, and Shinichi Miyagawa
- Subjects
endocrine system ,medicine.medical_specialty ,medicine.drug_class ,Pituitary gonadotropin ,Dehydrogenase ,Biology ,Endocrinology ,Nuclear receptor ,Meiosis ,Internal medicine ,Follicular phase ,medicine ,%22">Fish ,Gonadotropin ,Spermatogenesis - Abstract
17,20β-Dihydroxy-4-pregnen-3-one (17α,20β-DP) and 17,20β,21-Trihydroxy-4-pregnen-3-one (20β-S) are identified as maturation inducing steroids in teleost fish. 20β-S is produced from 11-deoxycortisol by 20β-hydroxysteroid dehydrogenase (20β-HSD) in ovarian follicular cells under the influence of pituitary gonadotropin. It stimulates the meiotic maturation of oocytes during GVBD. Biological actions of these steroids are mediated by both membrane and nuclear receptors.
- Published
- 2016
19. Gonadotropinsekretion und Gonadotropinreserve beim hypogonadotropen Hypogonadisms (Kurze Literaturübersicht und Fallbeschreibung)
- Author
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J. Mauss and G. Börsch
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Gynecology ,medicine.medical_specialty ,Hypogonadotropic eunuchoidism ,Endocrinology ,business.industry ,Urology ,Internal medicine ,Pituitary gonadotropin ,medicine ,Clomiphene test ,General Medicine ,business - Abstract
Zusammenfassung Bei einem Patienten mit hypogonadotropem Eunuchoidismus wurde der Clomiphentest zur Erfassung der hypothalamo-hypophysaren Funktionsreserve durchgefuhrt. Die Bestimmung der FSH/LH-Ausscheidung erfolgte mit neuen immunochemischen Testen im unkonzentrierten Urin. Wahrend und nach der Gabe von 200 mg Clomiphencitrat / die uber 13 Tage wurde kein signifikanter Anstieg der Gonadotropinausscheidung beobachtet. Ablauf und Nutzlichkeit des Clomiphentests in der Andrologie werden ausfuhrlich diskutiert. Abstract Clomiphene citrate stimulation of pituitary gonadotropin reserve was performed in a male with hypogonadotropic eunuchoidism. For evaluation, new immunochemical tests for simple determination of FSH and LH in unconcentrated urine were applied. No increase of FSH/LH-excretion was observed during or after administration of 200 mg clomiphene citrate / die for 13 days. Set-up and possible usefulness of the clomiphene test in andrology are discussed in detail. Resume Un test au clomiphene fut pratique chez un malade atteint d'eunuchoidisme hypogonado-tropique en vue de determiner la reserve fonctionnelle hypothalamo-hypophysaire. La determination de l'excretion de FSH et de LH fut executee a l'aide de nouveaux tests immunochimiques. Aucune elevation significative de l'excretion des gonadotropines fut observee pendant et apres 13 jours d'administration de citrate de clomiphene. L'application et l'utilite du test au clomiphene en andrologie furent amplement discutees.
- Published
- 2009
20. Treatment of central precocious puberty by GnRH analogs: long-term outcome in men
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Silvano Bertelloni and Dick Mul
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Adult ,Male ,End results ,medicine.medical_specialty ,Pediatrics ,Adolescent ,Secondary sex characteristic ,Urology ,Central precocious puberty ,Puberty, Precocious ,Gonadotropin-Releasing Hormone ,Humans ,Medicine ,Child ,Gynecology ,Sex Characteristics ,Dose-Response Relationship, Drug ,business.industry ,Pituitary gonadotropin ,Final height ,General Medicine ,Body Height ,Adult height ,Treatment Outcome ,Male patient ,business ,Sex characteristics - Abstract
In boys, central precocious puberty (CPP) is the appearance of secondary sex characteristics driven by pituitary gonadotropin secretion before the age of 9 years. In the last years, relevant improvements in the treatment of CPP have been achieved. Because CPP is rare in boys, the majority of papers on this issue focus on girls and do not address specific features of male patients regarding end results and safety. In the present paper, recent advances of CPP management with GnRH analogs in men are summarized. End results in untreated and treated patients are also reviewed by an analysis of the recently published literature on treatment of CPP in men. The available data indicate that therapy with GnRH analogs can improve final height into the range of target height without significant adverse short-term and long-term effects, but longer follow-up of larger series of patients is still required to draw definitive conclusions.
- Published
- 2008
21. Possible Role of Pituitary Gonadotropin in the Regulation of Neonatal Testicular Activity and Sexual Differentiation of the Brain in the Rat1
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K. Serisawa and Y. Arai
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medicine.medical_specialty ,Endocrinology ,Sexual differentiation ,Internal medicine ,Pituitary gonadotropin ,medicine ,Biology ,Psychoneuroendocrinology - Published
- 2015
22. Postpubertal Psychosexual Function in Males with Hypopituitarism
- Author
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Clopper, Richard R., Green, Richard, editor, Gemme, Robert, editor, and Wheeler, Connie Christine, editor
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- 1977
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23. The effect of acupuncture on ovulatory frequency and pituitary gonadotropin hormones in women with polycystic ovarian syndrome
- Author
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LM Pastore and D Li
- Subjects
medicine.medical_specialty ,business.industry ,media_common.quotation_subject ,Pituitary gonadotropin ,Polycystic ovary ,Endocrinology ,Complementary and alternative medicine ,Internal medicine ,Acupuncture ,Medicine ,Sham acupuncture ,business ,Ovulation ,media_common ,Hormone - Abstract
Pastore LM, Williams CD, Jenkins J, Patrie JT. True and sham acupuncture produced similar frequency of ovulation and improved LH to FSH ratios in women with polycystic ovary syndrome. Endocr Res 2011; 96: 3143–50.
- Published
- 2012
24. Effects of photoperiod on pituitary gonadotropin levels in masu salmon
- Author
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Masafumi Amano, Shoji Kitamura, Kazumasa Ikuta, and Katsumi Aida
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Male ,endocrine system ,medicine.medical_specialty ,Oncorhynchus ,medicine.drug_class ,Photoperiod ,chemistry.chemical_compound ,Internal medicine ,Testosterone treatment ,medicine ,Animals ,Testosterone ,photoperiodism ,biology ,Body Weight ,Pituitary gonadotropin ,General Medicine ,biology.organism_classification ,Endocrinology ,Castration ,chemistry ,Pituitary Gland ,%22">Fish ,Female ,Animal Science and Zoology ,Gonadotropin ,Orchiectomy ,Gonadotropins - Abstract
We examined the effects of photoperiod on pituitary levels of two types of gonadotropin (GTH), GTH I and GTH II, in masu salmon Oncorhynchus masou to study their mechanism of synthesis. In Experiment 1, the effects of long or short photoperiod combined with castration were examined using 8-month-old precocious males. Castration was carried out in early August and then the fish were reared under a short (8L16D) or long (16L8D) photoperiod for 60 days. In Experiment 2, the effects of photoperiod combined with testosterone treatment were examined using 12-month-old immature females. Silastic tubes containing testosterone (500 μg /fish) or vehicle were implanted intra-peritoneally in early October. Fish were reared under 16L8D for 60 days, and then half of the fish were transferred to 8L16D, while the remaining fish were kept under 16L8D until Day 90. In Experiment 1, GTH I contents were higher under 16L8D than under 8L16D in the castrated group on Day 30. Moreover, GTH I contents were higher in the castrated group than the control group under 16L8D on Day 30. GTH II contents increased with testicular maturation in the control groups, whereas they remained at low levels in the castrated groups regardless of photoperiodic treatment. In Experiment 2, GTH I contents did not change remarkably in all the groups, while GTH II contents were remarkably increased by testosterone treatment regardless of photoperiodic treatment. These results indicate that the synthesis of GTH I and GTH II are differently regulated by photoperiod and testosterone in masu salmon. J. Exp. Zool. 289:449–455, 2001. © 2001 Wiley-Liss, Inc.
- Published
- 2001
25. The role of amino acid neurotransmitters in the regulation of pituitary gonadotropin release in fish
- Author
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M MacMillan, D. Crump, S. Chiu, K. Larivière, Rüdiger W. Schulz, Vance L. Trudeau, David Spanswick, and E.J. Fraser
- Subjects
chemistry.chemical_classification ,endocrine system ,medicine.medical_specialty ,Pituitary gonadotropin ,Glutamate receptor ,Cell Biology ,Biology ,biology.organism_classification ,Biochemistry ,Amino acid ,chemistry.chemical_compound ,Endocrinology ,nervous system ,chemistry ,Internal medicine ,Pituitary hormones ,medicine ,%22">Fish ,Gluta ,Neurotransmitter ,Molecular Biology - Abstract
Both glutamate and γ-aminobutyric acid (GABA) are involved in pituitary hormone release in fish. Glutamate serves 2 purposes, both as a neurotransmitter and as a precursor for GABA synthesis. Glutamate can be catabolized to GABA by the actions of 2 distinct but related enzymes, glutamate decarboxylase 65 (GAD65) and GAD67. They derive from 2 different genes that likely arose from an early gene duplication prior to the emergence of teleosts more than 400 million years ago. There is good evidence for the involvement of GABA in luteinizing hormone (LH) release in fish. The mechanism of GABA action to stimulate LH release appears to be a combination of effects on GnRH release, potentiation of gonadotropin hormone-releasing hormone (GnRH) action, and in some cases directly at the LH cell. These actions appear to be dependent on such factors as sex or sex steroid levels, and there may also be species differences. Nevertheless, the stimulatory effects of GABA on LH are present in at least 4 fish species. In contrast, convincing data for the inhibitory effects of GABA on LH release have only been observed in 1 fish species. The sites and mechanisms of action of amino acid neurotransmitters on LH release have yet to be fully characterized. Both N-methyl-D-aspartic acid (NMDA) and S-α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) type glutamate receptors are likely to have important roles. We suggest that it is a receptor similar to the GABAA type which mediates the effects of GABA on LH release in fish, at least partially acting on the GnRH neuron, but likely directly acting at the gonadotroph as well. GABA may also be involved in regulating the release of other pituitary hormones in fish, namely follicle stimulating hormone (FSH = GTH-I), prolactin, and growth hormone. Based on the findings described in this review, a working model for the involvement of glutamate and GABA in the regulation of LH release in teleost fish is proposed. Key words: glutamate, GABA, luteinizing hormone, muscimol, patch clamp electrophysiology, reproduction, fish.
- Published
- 2000
26. [Untitled]
- Author
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Yan-Horn Lee, Fang-Yi Lee, Wen-Shiun Yueh, Jin-Lien Du, Ching-Fong Chang, and H. Tanaka
- Subjects
endocrine system ,medicine.medical_specialty ,Physiology ,medicine.drug_class ,Pituitary gonadotropin ,General Medicine ,Aquatic Science ,Biology ,Body weight ,Biochemistry ,Vitellogenin ,Endocrinology ,In vivo ,Internal medicine ,medicine ,biology.protein ,Acanthopagrus schlegeli ,%22">Fish ,Gonadotropin ,Testosterone - Abstract
The objective of the present study was to investigate the in vivo effects of different doses of 17β-estradiol (E2) and testosterone (T) on the levels of plasma and pituitary gonadotropin II (GTH II) in 2-year-old black porgy, Acanthopagrus schlegeli, during the spawning season. Male fish were distributed among 7 groups (n = 49), control, E2or T (with 3 doses, 2.4 ng, 72 ng and 2.2 μg g−1 body weight). Fish were injected with the respective vehicle or different doses of E2 or T on days 1 and 14. Plasma E2 levels were significantly increased in the 72 ng E2 group on days 8 and 14. Plasma vitellogenin levels were significantly higher in the 72 ng E2 group on days 14 and 20, and 2.2 μg E2 group on days 8, 14 and 20 than those in the control group. Plasma GTH II concentrations were significantly higher in the 2.2 μg E2 group than in the control and other E2groups on days 8, 14 and 20. Pituitary GTH II contents was significantly higher in the 7.2 ng E2 group compared to the control and other E2groups on day 20. Plasma GTH II concentrations were similar in the control and all the T groups on days 8, 14 and 20. None of the doses of T treatment stimulated pituitary GTH II content on day 20, although plasma vitellogenin levels were elevated. It is concluded that GTH II synthesis and secretion in black porgy is stimulated by an estrogen-specific effect.
- Published
- 1999
27. Effect of Tiangui recipe on serum leptin and pituitary gonadotropin in androgen-sterilized ratson serum leptin and pituitary gonadotropin in androgen-sterilized rats
- Author
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Sun Fei and Yu Jin
- Published
- 2000
- Full Text
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28. Effects of Water Temperature and Food Limitation on Pituitary Gonadotropin and Thyrotropin Subunit mRNA Levels in the Female Goldfish Carassius auratus
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Katsumi Aida, Yasutoshi Yoshiura, Young Chang Sohn, and Makito Kobayashi
- Subjects
medicine.medical_specialty ,Messenger RNA ,Endocrinology ,Water temperature ,medicine.drug_class ,Internal medicine ,Pituitary gonadotropin ,medicine ,Subunit mrna ,Carassius auratus ,Aquatic Science ,Gonadotropin ,Biology - Published
- 1998
29. [Untitled]
- Author
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Shoji Kitamura, Kazumasa Ikuta, Masafumi Amano, and Katsumi Aida
- Subjects
endocrine system ,medicine.medical_specialty ,Physiology ,Cerebrum ,Feedback control ,Pituitary gonadotropin ,General Medicine ,In situ hybridization ,Aquatic Science ,Biology ,biology.organism_classification ,Biochemistry ,Preoptic area ,chemistry.chemical_compound ,Castration ,medicine.anatomical_structure ,Endocrinology ,nervous system ,chemistry ,Internal medicine ,medicine ,Oncorhynchus ,hormones, hormone substitutes, and hormone antagonists ,Hormone - Abstract
Pituitary gonadotropin (GTH) secreting cells and brain gonadotropin-releasing hormone (GnRH) secreting neurons are known to be subjected to feedback control by gonadal steroid in teleosts. In masu salmon, Oncorhynchus masou, salmon GnRH (sGnRH) neurons in the ventral telencephalon (VT) and the preoptic area (POA) are involved in the control of GTH cells because sGnRH synthesis in these areas is activated with gonadal maturation. In this study, we attempted to clarify mechanisms of feedback control of sGnRH neurons by gonadal steroids. We examined the effects of 17α-methyltestosterone (MT) on sGnRH synthesis in yearling and 2-year-old female fish (which were immature during experimentation in May), and the effects of castration on sGnRH synthesis in underyearling precocious male fish in August. sGnRH synthesis in the POA, but not in the VT, was increased by MT administration in 2-year-old females only, indicating higher sensitivity to MT in the preoptic sGnRH neurons. Castration increased sGnRH synthesis in the VT but not in the POA. These results suggest that sGnRH neurons in the VT and those in the POA are differentially regulated by gonadal steroids.
- Published
- 1997
30. Neuroendocrine Control of Reproduction in Amphibians
- Author
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Pei-San Tsai
- Subjects
Amphibian ,endocrine system ,medicine.medical_specialty ,education.field_of_study ,Gonad ,biology ,media_common.quotation_subject ,Pituitary gonadotropin ,Population ,medicine.anatomical_structure ,Endocrinology ,Internal medicine ,biology.animal ,medicine ,Reproduction ,Neurohormones ,education ,Neuroscience ,Function (biology) ,media_common ,Hormone - Abstract
Publisher Summary The chapter provides an overview of the development, anatomy, and function of several reproductively relevant neuroendocrine systems. Further, their influences on the reproductive brain, pituitary gonadotropin (GTH) secretion, and peripheral organs such as the gonad are also discussed. It explains that the neurohormones secreted by the brain serve as important intermediaries that transduce environmental signals to peripheral tissues for reproductive regulation. The emerging evidence states that in mammals, the neuroendocrine regulation of amphibian reproduction is achieved principally through the actions of the gonadotropin-releasing hormone (GnRH) system. The chapter also discusses the ontogeny, function, and regulation of the amphibian GnRH systems. Additional roles of GnRH in peripheral reproductive regulation are also explored. Examining the neuroendocrine basis of amphibian reproduction provides an important means for understanding how disruption of the reproductive brain could occur under perturbed environmental conditions, leading to impaired fertility and declining population.
- Published
- 2011
31. Niftolide tests used in the diagnosis of male hypogonadism
- Author
-
A. G. Reznikov, Demchenko Vn, O. Ya. Boyarskaya, and S. V. Varga
- Subjects
endocrine system ,medicine.drug_class ,business.industry ,Endocrinology, Diabetes and Metabolism ,Pituitary gonadotropin ,Physiology ,Urine ,Antiandrogen ,Excretion ,Blood plasma ,medicine ,Differential diagnosis ,Gonadotropin ,business ,hormones, hormone substitutes, and hormone antagonists ,Gonadotropin level - Abstract
Comparative analysis with an antiandrogen niftolide and synthetic GnRF was carried out in 22 normal subjects, 14 patients with primary and 20 ones with secondary hypogonadism, and in 5 patients with clinical signs of gonadal insufficiency and obscure diagnosis in order to elucidate the pituitary gonadotropin reserves. Blood plasma and daily urine gonadotropin levels were measured. Changed gonadotropin excretion under the effect of niftolide in health and hypogonadism was in line with changed gonadotropin level in the blood after RF administration, this indicating a similar informative value of both tests for the differential diagnosis of various hypogonadism forms. In the first case measurements of blood gonadotropin were more informative, in the second daily urine analysis. Niftolide test, noninvasive and readily available, is recommended as an alternative test with RF administration.
- Published
- 1993
32. A Hormonal Contraceptive for Men: How Close are We?
- Author
-
Ilpo Huhtaniemi
- Subjects
Gynecology ,medicine.medical_specialty ,business.industry ,Research methodology ,Pituitary gonadotropin ,Clinical trial ,Clinical research ,Family planning ,Medicine ,business ,Intensive care medicine ,Developed country ,Pharmaceutical industry ,Hormone - Abstract
Novel contraceptive methods for men are still not available, and the opinions about their need among experts and lay public are polarized between enthusiasm and scepticism. Of the different strategies, hormonal methods aimed at suppression of spermatogenesis have been most extensively studies, are most promising, and are the only approach with the potential of breakthrough in the near future. Their principle is to block pituitary gonadotropin secretion, which will eliminate the endocrine stimulus for testicular androgen production, thereby eliminating its support for spermatogenesis. Testosterone alone or in combination with progestin is the most promising lead. However, many obstacles still have to be overcome before a practical and acceptable method is available. The reasons for the slow progress are partly biological and partly practical and economical. It is difficult to design a method that would be effective in most men, have no side effects and be reversible, economical, and acceptable by all cultures. Unfortunately, the pharmaceutical industry is currently not participating in the development work, and the research in the field is suffering from lack of political and financial support. Ironically, with relative modest additional effort a hormonal contraceptive method for men would be available. We review in this chapter the main principles of hormonal male contraception, the results of the latest clinical trials and shed light on some future perspectives in the field.
- Published
- 2010
33. The pituitary gonadotropin-releasing hormone (GnRH) receptor of the female rabbit: characterization and developmental aspects
- Author
-
E. C. Todoroff and Edward V. Younglai
- Subjects
medicine.medical_specialty ,Physiology ,Molecular Sequence Data ,Radioimmunoassay ,Down-Regulation ,Biology ,Iodine Radioisotopes ,Physiology (medical) ,Internal medicine ,medicine ,Animals ,Sexual maturity ,Amino Acid Sequence ,Binding site ,Pharmacology ,Membranes ,Gnrh receptor ,Pituitary gonadotropin ,Temperature ,General Medicine ,Luteinizing Hormone ,Endocrinology ,Isotope Labeling ,Pituitary Gland ,Female ,Rabbits ,Female rabbit ,Receptors, LHRH ,Hormone - Abstract
The aim of the present study was to characterize the pituitary gonadotropin-releasing hormone (GnRH) binding site in the rabbit and investigate its possible role in sexual maturation of the female rabbit. A radioligand binding assay was established, and the presence of specific 125I-labelled D-Ala6-des-Gly10-GnRH ethylamide (125I-DAla6EA) binding sites in the anterior pituitary gland of the rabbit was demonstrated. 125I-DAla6EA binding was saturable, specific, displaceable, reversible, correlated with increasing tissue concentrations, and susceptible to physiological manipulation. 125I-DAla6EA binding indicated the presence of two binding sites in the female adult rabbit pituitary: a high affinity, low capacity site (KD = 0.3–0.4 nM; Bmax = 100–200 fmol/mg protein) and a lower affinity, high capacity site (KD = 30 nM; Bmax = 5–8000 fmol/mg protein). Ontogeny of 125I-DAla6EA binding in the female rabbit (40–120 days of age) did not show a correlation between binding site number and serum luteinizing hormone (LH). In addition, the net serum LH response in female rabbits to a subcutaneous injection of DAla6EA (10 ng, 100 ng, and 1 μg per kilogram body weight) was not significantly different between animals 40, 75, and 120 days of age. This suggests that a decrease in pituitary responsiveness to GnRH is not associated with sexual maturation in the female rabbit. Results indicate that factors other than and (or) in addition to GnRH binding site number, such as postreceptor events, play a role in gonadotropin secretion in the female rabbit.Key words: gonadotropin-releasing hormone, receptors, luteinizing hormone, female rabbit.
- Published
- 1992
34. Pituitary gonadotropin responsiveness to repeated gonadotropin releasing hormone (GnRH) stimulations in patients with chronic anovulation
- Author
-
S. Schramm, Winfried G. Rossmanith, Christian Lauritzen, and R. Benz
- Subjects
Adult ,endocrine system ,medicine.medical_specialty ,Endocrinology, Diabetes and Metabolism ,Stimulation ,Gonadotropin-releasing hormone ,Gonadotropin-Releasing Hormone ,Andrology ,Anovulation ,Basal (phylogenetics) ,Follicle-stimulating hormone ,Endocrinology ,Internal medicine ,medicine ,Humans ,In patient ,business.industry ,Pituitary gonadotropin ,Obstetrics and Gynecology ,Luteinizing Hormone ,medicine.disease ,Female ,Follicle Stimulating Hormone ,Luteinizing hormone ,business ,hormones, hormone substitutes, and hormone antagonists - Abstract
To evaluate whether repeated gonadotropin releasing hormone (GnRH) stimulations were superior to single GnRH administrations for the accurate assessment of pituitary gonadotropin responsiveness, the GnRH-stimulated luteinizing hormone (LH) and follicle stimulating hormone (FSH) responses of 49 hyperandrogenic patients (HA) were compared with those of 20 hypogonadotropic patients (HH) and of 24 normally cycling women (N). Blood samples were obtained at frequent intervals during GnRH administrations (25 micrograms twice within 2 h). Unstimulated LH concentrations were higher (p less than 0.001) in HA than in N and HH women. However, basal FSH levels differed only in HA from HH women (p less than 0.001). Following either GnRH stimulation, increased (p less than 0.01) LH and FSH releases were noted in all N, HA and HH women. The GnRH-stimulated LH and FSH responses to either GnRH injections were highest (p less than 0.01) in HA and lowest (p less than 0.01 vs. N) in HH women. The net LH and FSH increases over unstimulated concentrations (delta LH or FSH) in response to either GnRH stimulation were highest (p less than 0.01 or less) in HA women. By contrast, no differences were determined in the delta LH and FSH levels between the first and second GnRH stimulations within each group. These observations document different unstimulated and stimulated gonadotropin concentrations in normal cycling and anovulatory women. Gonadotropin responses to single GnRH administrations differ for anovulatory patients. Since the gonadotropin responses to the second GnRH stimulation are comparable to those during the first GnRH injections, repeated GnRH stimulations may not help to distinguish the degree of pituitary responsiveness in ovulatory from anovulatory women.
- Published
- 1991
35. Biochemical Fractions and Mechanisms Involved in the Pineal Modulation of Pituitary Gonadotropin Release
- Author
-
C. Kordon, I. Ebels, and A. Moszkowska
- Subjects
medicine.medical_specialty ,Endocrinology ,Internal medicine ,Pituitary gonadotropin ,medicine ,Biology - Published
- 2008
36. Some Observations on the Clinical Value of Pituitary Gonadotropin Assays in Human Urine
- Author
-
J. A. Loraine
- Subjects
medicine.medical_specialty ,business.industry ,Pituitary gonadotropin ,Physiology ,Seminoma ,Urine ,medicine.disease ,Mammary carcinoma ,Endocrinology ,Internal medicine ,Clinical value ,Medicine ,Testicular tumours ,business - Published
- 2008
37. Photoaffinity Labeling of Pituitary Gonadotropin-Releasing Hormone Receptors in Goldfish (Carassius Auratus)1
- Author
-
Eli Hazum, Hamid R. Habibi, and Richard E. Peter
- Subjects
Agonist ,endocrine system ,Photoaffinity labeling ,medicine.drug_class ,Pituitary gonadotropin ,Cell Biology ,General Medicine ,Biology ,Ligand (biochemistry) ,Reproductive Medicine ,Biochemistry ,Hormone receptor ,Carassius auratus ,medicine ,Binding site ,Receptor ,hormones, hormone substitutes, and hormone antagonists - Abstract
Receptors for GnRH were labeled by use of an iodinated (125I) photoreactive GnRH derivative [D-Lys6-azidobenzoyl]-GnRH. This derivative was found to bind to two classes of GnRH binding sites: high-affinity/low-capacity sites and low-affinity/high-capacity sites. The binding affinity of [D-Lys6-azidobenzoyl]-GnRH was found to be greater than that of D-Lys6-GnRH, but lower than a superactive fish GnRH agonist [D-Arg6, Trp7, Leu8, Pro9-NEt]-GnRH (sGnRH-A). Analysis of the photoaffinity-labeled goldfish pituitary GnRH receptors by SDS-PAGE and autoradiography indicated the presence of three labeled proteins displaceable by unlabeled sGnRH-A. The first and the most prominently labeled band was a 71,000-Mr protein, the second a 51,000-Mr protein, and the third a minor band of 130,000 Mr. Displacement characteristics of the 71,000- and 130,000-Mr bands were consistent with those of the low-affinity binding sites; displacement of the iodinated ligand from these proteins was achieved only in the presence of 10(-6) M sGnRH-A. The 51,000-Mr band had characteristics similar to those of the high-affinity site; displacement of the labeled ligand was achieved in the presence of 10(-9) M sGnRH-A. These findings provide for the first time some biochemical characterizations of pituitary GnRH receptors in a nonmammalian vertebrate.
- Published
- 1990
38. Interplay between dose and frequency of GnRH administration in determining pituitary gonadotropin responsiveness
- Author
-
Stephanie B. Seminara, William F. Crowley, Paul A. Boepple, and Virginia A. Hughes
- Subjects
Male ,medicine.medical_specialty ,Pituitary gland ,Endocrinology, Diabetes and Metabolism ,Stimulation ,Gonadotropic cell ,Drug Administration Schedule ,Gonadotropin-Releasing Hormone ,Cellular and Molecular Neuroscience ,Endocrinology ,Internal medicine ,Medicine ,Humans ,Gonadotropins pituitary ,Lh secretion ,Dose-Response Relationship, Drug ,Endocrine and Autonomic Systems ,business.industry ,Hypogonadism ,Pituitary gonadotropin ,Luteinizing Hormone ,medicine.anatomical_structure ,Pituitary Gland ,business ,Luteinizing hormone ,Gonadotropins ,Endocrine gland - Abstract
Background/Aims: The dose, frequency and contour of GnRH stimulation of the pituitary gonadotrope have been shown to be independent variables influencing pituitary LH secretion. The dynamic interaction between these variables during physiological and pathophysiological states has yet to be examined. Methods: Twelve men with GnRH deficiency and idiopathic hypogonadotropic hypogonadism undergoing GnRH therapy participated in a series of studies in which 2 log orders of GnRH doses (2.5–250 ng/kg) were administered at frequencies varying from 0.5 to 8 hourly. Pituitary responses were characterized by pulse amplitudes and nadirs. The relative sensitivity of the gonadotrope to GnRH was defined as that dose of GnRH capable of eliciting an LH pulse amplitude equal to the mean LH amplitude in normal men. Results: As GnRH stimulation of the gonadotrope slowed from 0.5 to 8 hourly, pulse amplitudes of LH increased whereas mean nadirs decreased (p < 0.05). Unique, curvilinear dose-response curves were found for each frequency that demonstrated an increasing slope (p < 0.03) as the frequency of GnRH stimulation slowed. Thus, the relative sensitivity of the gonadotrope increased as the frequency of GnRH stimulation decreased over the range of physiological frequencies tested. Conclusions: We conclude that a delicate interplay exists between the dose and frequency of GnRH stimulation of the gonadotrope that determines pituitary LH gonadotropin responsiveness in the human. Slower frequencies favor increased LH release largely due to decreasing LH nadirs and improved sensitivity of the gonadotropes to GnRH stimulation.
- Published
- 2007
39. Nonhuman primates contribute unique understanding to anovulatory infertility in women
- Author
-
Deborah K. Bernett, David H. Abbott, Shu C. Foong, and Daniel A. Dumesic
- Subjects
Leptin ,Primates ,Time Factors ,medicine.drug_class ,Reproductive Endocrinology ,Hypothalamus ,Physiology ,General Biochemistry, Genetics and Molecular Biology ,Anovulation ,Gonadotropin-Releasing Hormone ,Stress, Physiological ,medicine ,Animals ,Humans ,Ovarian Diseases ,Fetal programming ,Clinical treatment ,business.industry ,Pituitary gonadotropin ,General Medicine ,medicine.disease ,Nonhuman primate ,Hyperprolactinemia ,Disease Models, Animal ,Animal Science and Zoology ,Female ,Gonadotropin ,business ,Infertility, Female ,Hormone - Abstract
Anovulatory infertility affects a large proportion of reproductive-aged women. Major improvements in successful clinical treatment of this prevalent disorder in women's health have been made possible because of biomedical research employing nonhuman primates. Experiments on female rhesus monkeys were the first to demonstrate that the key hypothalamic neurotransmitter, gonadotropin-releasing hormone, involved in stimulating pituitary gonadotropin synthesis, storage, and release was bioactive only when released in approximately hourly bursts. This breakthrough in understanding gonadotropin regulation enabled identification of hypogonadotropic, apparently normogonadotropic, and hypergonadotropic forms of anovulatory infertility, and development of appropriate stimulatory or inhibitory gonadotropin therapies. Treatments to overcome anovulatory infertility represent one of the major advances in clinical reproductive endocrinology during the last 25 yr. The future promise of nonhuman primate models for human ovulatory dysfunction, however, may be based on an increased understanding of molecular and physiological mechanisms responsible for fetal programming of adult metabolic and reproductive defects and for obesity-related, hyperinsulinemic impairment of oocyte development.
- Published
- 2004
40. Reproductive Endocrinology of the European Eel, Anguilla anguilla
- Author
-
Sylvie Dufour, Bernadette Vidal, Nadine Le Belle, Miskal Sbaihi, and Elisabeth Burzawa-Gerard
- Subjects
media_common.quotation_subject ,Pituitary gonadotropin ,Reproductive Endocrinology ,Zoology ,Biology ,Reproduction ,Luteinizing hormone ,media_common - Abstract
The mystery of the reproduction of the European eel, in which “seminal liquor nor eggs could never be observed;” was questioned as early as Greek antiquity, by Aristotle, in his writings on “Animal History” and “Animal Generation.” This question initiated a long and still open quest, for the discovery of the eel life cycle and reproduction.
- Published
- 2003
41. Effects of thyroid status on pituitary gonadotropin and testicular reserve in men
- Author
-
E. M. Velázquez and G. Bellabarba Arata
- Subjects
Adult ,Male ,endocrine system ,medicine.medical_specialty ,Gonadotropin RH ,endocrine system diseases ,Adolescent ,Thyroid Gland ,Thyrotropin ,Disease ,Testicle ,Biology ,Endocrinology ,Hypothyroidism ,Thyroid dysfunction ,Internal medicine ,Testis ,medicine ,Humans ,Estradiol ,Thyroid disease ,17-alpha-Hydroxyprogesterone ,Thyroid ,Pituitary gonadotropin ,Luteinizing Hormone ,Middle Aged ,medicine.disease ,Graves Disease ,Thyroxine ,medicine.anatomical_structure ,Gonadotropins, Pituitary ,Follicle Stimulating Hormone - Abstract
This investigation was conducted to evaluate the effect of thyroid dysfunction on the pituitary-gonadal axis. Ten men with Graves' disease and 5 hypothyroid patients were studied; 10 normal males were studied as a control group. In untreated conditions hyperthyroidism was associated with a normal serum-free testosterone concentration, an increased serum of 17OHP levels, a reduced testosterone response to hCG stimulation, and a hyperresponse of LH to GnRH. These abnormalities reverted after normalization of high FT4 serum levels. Untreated hypothyroid men showed a normal hormone sex response to hCG, but the LH responst to GnRH was reduced, with a tendency to improve after T4 supplementation. There was a strong and significant negative correlation between FT4 and testosterone response, expressed as an area under the curve, and a positive correlation with LH response to GnRH. Despite normal basal free testosterone concentrations, 70% of hyperthyroid and 60% of hypothyroid patients had complaints of decreased libido. The results suggest that thyroid hormones play an important dual pituitary-gonadal effect that is reflected by an impairment of testicular testosterone synthesis associated to hyperresponse to LH in hyperthyroidism and a defective LH response to GnRH in hypothyroidism.
- Published
- 1997
42. Changes in GnRH levels in the brain and pituitary gland during migrations of sockeye salmon and chum salmon
- Author
-
H. Ueda, T. Kitani, Munehico Iwata, S. Matsumoto, Hideaki Yamada, and Masafumi Amano
- Subjects
endocrine system ,medicine.medical_specialty ,Pituitary gland ,Physiology ,Thyroid ,Pituitary gonadotropin ,General Medicine ,Aquatic Science ,Biology ,biology.organism_classification ,Biochemistry ,Endocrinology ,medicine.anatomical_structure ,Internal medicine ,medicine ,Oncorhynchus ,hormones, hormone substitutes, and hormone antagonists ,Hormone ,Smoltification - Abstract
Levels of two moleculer types of gonadotropin-releasing hormone (GnRH), salmon GnRH (sGnRH) and chicken GnRH–II (cGnRH–II) in the various brain regions and pituitary gland of sockeye salmon (Oncorhynchus nerka) and chum salmon (O. keta) during smoltification and spawning migration, respectively, were measured using specific time-resolved fluoroimmunoassay (TR-FIA) systems. Changes in sGnRH levels in different brain regions tended to be specifically synchronized with serum thyroid hormone or pituitary gonadotropin (GTH) levels during smoltification and spawning migration, respectively. In contrast, cGnRH–II levels did not show such synchronized changes. SGnRH and cGnRH–II in various brain regions might have different roles during smoltification and spawning migration of salmonid fishes.
- Published
- 2003
43. Pharmacology of Contraceptive Steroids
- Author
-
Joseph W. Goldzieher
- Subjects
business.industry ,Manufacturing process ,medicine.drug_class ,Pituitary gonadotropin ,Contraceptive steroid ,Pharmacology ,Mestranol ,Estrogen ,Breakthrough bleeding ,Estrogenic Effects ,Medicine ,medicine.symptom ,business ,Norethynodrel ,medicine.drug - Abstract
The use of 17α-ethynyl estrogens in contraceptive formulations originated by accident. The first 19-norprogestins to be used for contraceptive purposes (norethindrone and norethynodrel) were contaminated during the manufacturing process with an estrogen, mestranol — the 3-methyl ether of ethynyl estradiol. The degree of contamination, 0.15%, appeared trivial to the chemists, but meant that every clinical dose of 10 mg norethindrone (that was the original contraceptive dose) included 150 micrograms mestranol, which produced nausea and other side-effects. When the clinical impact of this contaminant was recognized it was removed, but the resulting formulation produced unacceptable breakthrough bleeding, so a “standard”amount—60 micrograms—was added to each norethindrone tablet to correct this problem. It was not recognized at the time that ethynyl estrogens are disproportionately powerful in their inhibition of pituitary gonadotropin secretion compared to their other estrogenic effects. This fortuitous property was the basis of oral contraceptive formulations called “sequentials,” which had a brief career in the United States, but were used for a much longer period of time in other parts of the world.
- Published
- 1993
44. Complete ovarian unresponsiveness to hMG stimulation after prolonged GnRH analogue administration
- Author
-
H. Kaneti, M. Fejgin, Yehudith Ghetler, S. Goldberger, I. Ben-nun, and R. Jaffe
- Subjects
Adult ,endocrine system ,medicine.medical_specialty ,Menotropins ,Endocrinology, Diabetes and Metabolism ,Stimulation ,Biology ,Luteal Phase ,Buserelin ,Gonadotropin-Releasing Hormone ,Endocrinology ,Desensitization (telecommunications) ,In vivo ,Internal medicine ,medicine ,Humans ,Receptor ,Inhibitory effect ,Progesterone ,Estradiol ,Pituitary gonadotropin ,Ovary ,Obstetrics and Gynecology ,Luteinizing Hormone ,Plasma concentration ,HMG-CoA reductase ,biology.protein ,Female ,Follicle Stimulating Hormone ,hormones, hormone substitutes, and hormone antagonists - Abstract
GnRH agonists (GnRH-a) have recently been shown to exert an inhibitory effect on human reproductive functions, the mechanism for this effect being attributed solely to the desensitization of the pituitary gonadotropin receptors to GnRH-a. We present two cases where chronic treatment with a GnRH-a caused complete suppression of ovarian activity in vivo. The effect could not be counteracted by large hMG doses and resulted in high FSH plasma concentrations. Normal ovarian activity was restored only after withdrawal of GnRH-a.
- Published
- 1990
45. USE OF MAMMALIAN GONADOTROPIN-RELEASINC HORMONE TO CHARACTERIZE PITUITARY GONADOTROPIN RELEASING HORMONE RECEPTORS IN WHITE STURGEON (Acipenser transtnontanus RICHARDSON)
- Author
-
B. Mojazi Amiri, Serge I. Doroshov, T E Adams, and Gary P. Moberg
- Subjects
medicine.medical_specialty ,medicine.drug_class ,Pituitary gonadotropin ,Aquatic Science ,Biology ,biology.organism_classification ,Gonadotropic cell ,White (mutation) ,Endocrinology ,Sturgeon ,Hormone receptor ,Internal medicine ,medicine ,Acipenser ,Gonadotropin ,Hormone - Published
- 1999
46. Tracing pituitary gonadotropin recipients
- Author
-
Sarah Ramsay
- Subjects
medicine.medical_specialty ,Endocrinology ,business.industry ,Internal medicine ,Pituitary gonadotropin ,medicine ,General Medicine ,Tracing ,business - Published
- 1993
47. Endothelins as a modulator of pituitary gonadotropin release
- Author
-
Izumi, Shun Ichiro, Suguru Saito, Tsunehisa Makino, Toshihiko Iida, and Shiro Nozawa
- Subjects
Endothelins ,medicine.hormone ,medicine.medical_specialty ,Endocrinology ,Chemistry ,Internal medicine ,Pituitary gonadotropin ,medicine ,General Medicine - Published
- 1992
48. Effects of Parturition and Suckling on Concentrations of Pituitary Gonadotropins, Hypothalamic GnRH and Pituitary Responsiveness to GnRH in Ewes
- Author
-
Niswender, G. D., Nett, T. M., Moss, G. E., and Adams, T. E.
- Subjects
CHILDBIRTH ,EWES - Published
- 1980
49. Comparative aspects of the assay of carp gonadotropin
- Author
-
M.D Wiegand, David R. Idler, and H.C.H Komourdjian
- Subjects
endocrine system ,medicine.medical_specialty ,biology ,medicine.drug_class ,Pituitary gonadotropin ,Ovary ,General Medicine ,biology.organism_classification ,Carp gonadotropin ,Grass carp ,medicine.anatomical_structure ,Endocrinology ,Internal medicine ,medicine ,Bioassay ,sense organs ,Gonadotropin ,Carp ,hormones, hormone substitutes, and hormone antagonists - Abstract
1. 1. Estimation of gonadotropin content of five batches of carp pituitaries by three assay systems yielded similar relative potencies. The assays differed in their estimates of absolute pituitary gonadotropin content. 2. 2. Carp gonadotropin was found to be more potent than salmonid gonadotropins in a bioassay based on cyclic AMP accumulation in immature grass carp ovary.
- Published
- 1984
50. Gonadotropins in the Infant Chimpanzee: A Sex Difference
- Author
-
D. Grotts, Charles Faiman, and Jeremy S.D. Winter
- Subjects
Male ,Periodicity ,medicine.medical_specialty ,Pan troglodytes ,Pituitary gonadotropin ,Luteinizing Hormone ,General Biochemistry, Genetics and Molecular Biology ,Fsh levels ,Sex Factors ,Endocrinology ,Research council ,Internal medicine ,Statistical analyses ,Agency (sociology) ,medicine ,Animals ,Female ,Follicle Stimulating Hormone ,Psychology ,Demography - Abstract
SummarySerial circulating levels of FSH were higher in five female than in four male infant (0.4-2.0 years) chimpanzees. A rhythm in FSH levels was observed in the females with a periodicity of 8–25 days. There was no sex difference in mean LH levels. However, greater day-to-day variability was observed in the females.The animals used in the study were handled in accordance with the “Guide for Laboratory-Animal Facilities and Care” established by The National Academy of Science-National Research Council. This work was supported in part by M. R. C. Canada Grant MA-2997 and by N. I. H. Contract DRR-73-2100. The LER-907 human pituitary gonadotropin standard was a gift of the National Pituitary Agency. We thank Dr. F. S. Chebib for help with the statistical analyses and Mrs. R. Poturnak, Mrs. E. Dudeck, and Mr. D. Bookout for technical assistance.
- Published
- 1973
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