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Registro Completo |
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Biblioteca(s): |
Embrapa Caprinos e Ovinos. |
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Data corrente: |
18/09/2018 |
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Data da última atualização: |
18/09/2018 |
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Autoria: |
THIÉRY, J. C.; MARTIN G. B. |
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Título: |
Neurophysiological control of the secretion of gonadotrophin-releasing hormone and luteinizing hormone in the sheep: a review. |
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Ano de publicação: |
1991 |
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Fonte/Imprenta: |
Reproduction, Fertility and Development, v. 3, n. 2, p. 137-173, 1991. |
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Idioma: |
Inglês |
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Conteúdo: |
Abstract: The anterior pituitary gland secretes pulses of luteinizing hormone (LH) in response to pulses of gonadotrophin-releasing hormone (GnRH) released into the hypophysial portal blood by the hypothalamus. The pulsatile nature of the secretions is very important because the frequency of the pulses is directly related to the activity of the GnRH neurons. We can therefore take advantage of this phenomenon to develop mechanistic interpretations of responses to experimental treatments designed to unravel the neural pathways that influence what is, arguably, the most important individual signal controlling the activity of the reproductive system. We might also resolve the disagreements in the literature covering the neuropharmacology of gonadotrophin secretion. In this review, we describe work towards this end in the sheep. Most (95%) of the 2500 GnRH cell bodies in the sheep brain are located in a region covering the anterior hypothalamus, the medial preoptic area, the diagonal band of Broca, and the septum. The axons of up to 50% of these cells terminate in the organum vasculosum of the lamina terminalis. The remainder terminate in the median eminence and form the final common pathway for the many factors that affect gonadotrophin secretion. Among the factors known to affect the frequency of the pulses (or the activity of the GnRH neurons) are nutrition, pheromones, photoperiod and gonadal steroids (negative and positive feedback). Factors that affect GnRH pulse amplitude are more difficult to determine because variations in pituitary responsiveness prevent the use of LH patterns as a 'bioassay'. Techniques developed recently have allowed the direct measurement of GnRH pulse amplitude and revealed inhibitory effects of oestradiol, but we do not know whether this effect is due to a reduction in the amount of GnRH released by each neurone or a reduction in the number of neurones releasing a pulse. It is unlikely that the factors that alter pulse frequency do so by directly affecting the GnRH cells. For example, it is obvious that other cells, with specific receptors for pheromonal or nutritional stimuli, formulate a signal that is transferred to the GnRH cells via interneurones. Similarly, it is likely that a hypothalamic clock intervenes between photoperiodic inputs and GnRH output. Opioidergic neurons have been proposed as a link in this system, but the complexity of their action makes it unlikely that they directly affect the GnRH neurons. The responses to steroids are simple and rapid, but steroid receptors have not been found in GnRH cells, so at least one other set of interneurones is involved. MenosAbstract: The anterior pituitary gland secretes pulses of luteinizing hormone (LH) in response to pulses of gonadotrophin-releasing hormone (GnRH) released into the hypophysial portal blood by the hypothalamus. The pulsatile nature of the secretions is very important because the frequency of the pulses is directly related to the activity of the GnRH neurons. We can therefore take advantage of this phenomenon to develop mechanistic interpretations of responses to experimental treatments designed to unravel the neural pathways that influence what is, arguably, the most important individual signal controlling the activity of the reproductive system. We might also resolve the disagreements in the literature covering the neuropharmacology of gonadotrophin secretion. In this review, we describe work towards this end in the sheep. Most (95%) of the 2500 GnRH cell bodies in the sheep brain are located in a region covering the anterior hypothalamus, the medial preoptic area, the diagonal band of Broca, and the septum. The axons of up to 50% of these cells terminate in the organum vasculosum of the lamina terminalis. The remainder terminate in the median eminence and form the final common pathway for the many factors that affect gonadotrophin secretion. Among the factors known to affect the frequency of the pulses (or the activity of the GnRH neurons) are nutrition, pheromones, photoperiod and gonadal steroids (negative and positive feedback). Factors that affect GnRH pulse amplitude ... Mostrar Tudo |
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Palavras-Chave: |
Physiological Phenomena. |
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Thesaurus Nal: |
Animal physiology; Catecholamines; Electrophysiology; Gonadotropin-releasing hormone; Luteinizing hormone; Nervous system; Secretion; Sheep. |
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Categoria do assunto: |
L Ciência Animal e Produtos de Origem Animal |
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Marc: |
LEADER 03398naa a2200241 a 4500
001 2095970
005 2018-09-18
008 1991 bl uuuu u00u1 u #d
100 1 $aTHIÉRY, J. C.
245 $aNeurophysiological control of the secretion of gonadotrophin-releasing hormone and luteinizing hormone in the sheep$ba review.
260 $c1991
520 $aAbstract: The anterior pituitary gland secretes pulses of luteinizing hormone (LH) in response to pulses of gonadotrophin-releasing hormone (GnRH) released into the hypophysial portal blood by the hypothalamus. The pulsatile nature of the secretions is very important because the frequency of the pulses is directly related to the activity of the GnRH neurons. We can therefore take advantage of this phenomenon to develop mechanistic interpretations of responses to experimental treatments designed to unravel the neural pathways that influence what is, arguably, the most important individual signal controlling the activity of the reproductive system. We might also resolve the disagreements in the literature covering the neuropharmacology of gonadotrophin secretion. In this review, we describe work towards this end in the sheep. Most (95%) of the 2500 GnRH cell bodies in the sheep brain are located in a region covering the anterior hypothalamus, the medial preoptic area, the diagonal band of Broca, and the septum. The axons of up to 50% of these cells terminate in the organum vasculosum of the lamina terminalis. The remainder terminate in the median eminence and form the final common pathway for the many factors that affect gonadotrophin secretion. Among the factors known to affect the frequency of the pulses (or the activity of the GnRH neurons) are nutrition, pheromones, photoperiod and gonadal steroids (negative and positive feedback). Factors that affect GnRH pulse amplitude are more difficult to determine because variations in pituitary responsiveness prevent the use of LH patterns as a 'bioassay'. Techniques developed recently have allowed the direct measurement of GnRH pulse amplitude and revealed inhibitory effects of oestradiol, but we do not know whether this effect is due to a reduction in the amount of GnRH released by each neurone or a reduction in the number of neurones releasing a pulse. It is unlikely that the factors that alter pulse frequency do so by directly affecting the GnRH cells. For example, it is obvious that other cells, with specific receptors for pheromonal or nutritional stimuli, formulate a signal that is transferred to the GnRH cells via interneurones. Similarly, it is likely that a hypothalamic clock intervenes between photoperiodic inputs and GnRH output. Opioidergic neurons have been proposed as a link in this system, but the complexity of their action makes it unlikely that they directly affect the GnRH neurons. The responses to steroids are simple and rapid, but steroid receptors have not been found in GnRH cells, so at least one other set of interneurones is involved.
650 $aAnimal physiology
650 $aCatecholamines
650 $aElectrophysiology
650 $aGonadotropin-releasing hormone
650 $aLuteinizing hormone
650 $aNervous system
650 $aSecretion
650 $aSheep
653 $aPhysiological Phenomena
700 1 $aMARTIN G. B.
773 $tReproduction, Fertility and Development$gv. 3, n. 2, p. 137-173, 1991.
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Registro original: |
Embrapa Caprinos e Ovinos (CNPC) |
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| Registros recuperados : 3 | |
| 1. |  | KELLEY, B. S.; LEE, S.-J.; DAMASCENO, C. M. B.; CHAKRAVARTHY, S.; KIM, B.-D.; MARTIN, G. B.; ROSE, J. K. C. A secreted effector protein (SNE1) from Phytophthora infestans is a broadly acting suppressor of programmed cell death. The Plant Journal, v. 62, p. 357-366, 2010.| Tipo: Artigo em Periódico Indexado | Circulação/Nível: A - 1 |
| Biblioteca(s): Embrapa Milho e Sorgo. |
|    |
| 2. | | RIVERO, M. J.; LOPEZ-VILALOBOS, N.; EVANS, A.; BERNDT, A.; CARTMILL, A.; NEAL, A. L.; MCLAREN, A.; FARRUGGIA, A.; MIGNOLET, C.; CHADWICK, D.; MCCRACKEN, D.; BUSCH, D.; MARTIN, G. B.; FLEMING, H.; SHERIDAN, H.; GIBBONS, J.; MERBOLD, L.; EISLER, M.; LAMBE, N.; ROVIRA, P.; HARRIS, P.; MURPHY, P.; VERCOE, P. E.; WILLIAMS, P.; MACHADO, R.; TAKAHASHI, T.; PUECH, T.; BOLAND, T.; AYALA, W.; LEE, M. R. F. Key traits for ruminant livestock across diverse production systems in the context of climate change: perspectives from a global platform of research farms. Reproduction, Fertility and Development, v. 33, p. 1-19, 2021.| Tipo: Artigo em Periódico Indexado | Circulação/Nível: A - 1 |
| Biblioteca(s): Embrapa Pecuária Sudeste. |
|  |
| 3. | | RIVERO, M. J.; EVANS, A. C. O.; BERNDT, A.; CARTMILL, A.; DOWSEY, A.; FARRUGGIA, A.; MIGNOLET, C.; ENRIQUEZ-HIDALGO, D.; CHADWICK, D.; MCCRACKEN, D. I.; BUSCH, D.; PEREYRA, F.; MARTIN, G. B.; SANFORD, G. R.; SHERIDAN, H.; WRIGHT, I.; BRUNET, L.; EISLER, M. C.; LOPEZ-VILLALOBOS, N.; ROVIRA, P.; HARRIS, P.; MURPHY, P.; WILLIAMS, A. P.; JACKSON, R. D.; MACHADO, R.; SURAJ, P. T.; PUECH, T.; BOLAND, T. M.; AYALA, W.; LEE, M. R. F. Taking the steps toward sustainable livestock: our multidisciplinary global farm platform journey. Animal Frontiers, v.11, n.5, p.52-58, oct. 2021.| Tipo: Artigo em Periódico Indexado | Circulação/Nível: B - 5 |
| Biblioteca(s): Embrapa Pecuária Sudeste. |
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| Registros recuperados : 3 | |
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