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Titolo:
NEUROENDOCRINE CONTROL OF OVULATION IN SH EEP
Autore:
CARATY A; KARSCH FJ; HERBISON A; BRUNEAU G; DELALEU B; VENIER G; FABRENYS C;
Indirizzi:
INRA,PHYSIOL REPROD MAMMIFERES DOMEST STN F-37380 NOUZILLY FRANCE UNIV MICHIGAN ANN ARBOR MI 48109 BABRAHAM INST CAMBRIDGE CB2 4AC ENGLAND
Titolo Testata:
Annales d'Endocrinologie
fascicolo: 5, volume: 56, anno: 1995,
pagine: 539 - 542
SICI:
0003-4266(1995)56:5<539:NCOOIS>2.0.ZU;2-U
Fonte:
ISI
Lingua:
FRE
Soggetto:
GONADOTROPIN-RELEASING-HORMONE; RECEPTOR-IMMUNOREACTIVE CELLS; ESTROUS-CYCLE; OVARIECTOMIZED EWES; ESTRADIOL; SURGE; SECRETION; GNRH; RAT; NEURONS;
Keywords:
GNRH; OVULATION; SHEEP;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
27
Recensione:
Indirizzi per estratti:
Citazione:
A. Caraty et al., "NEUROENDOCRINE CONTROL OF OVULATION IN SH EEP", Annales d'Endocrinologie, 56(5), 1995, pp. 539-542

Abstract

The preovulatory surge of LH, or positive feedback response to oestradiol, is related to the steroid's direct stimulating action on the pituitary gland, but we have demonstrated that, in sheep, the central nervous system plays an essential role in its action : a preovulatory GnRH surge. Since GnRH neurons appear to contain few, if any receptors for oestradiol the question is raised: Where in the central nervous system does oestradiol act to stimulate GnRH secretion ? A series of experiments were conducted with a combination of techniques for sampling pituitary portal blood and stereotaxic brain micro-implantations of of oestradiol. Castrated Ile-deFrance breed ewes were treated during the pseudo follicular phase of successive artifical cycles, receiving either peripheral oestradiol implants or brain implants containing oestradiol or cholesterol. Administration of oestradiol implants into the ventromedial region of the hypothalamus induced a preovulatory GnRH surge in 5 out of 10 animals. The interval between oestradiol and the GnRH surge was comparable with that observed in animals treated with a peripheral implant although the amplitude of the surge was smaller. No GnRHsurges were observed in animals treated with cholesterol. Finally, there was an inverse correlation between the response intensity (amplitude of the GnRH/LH surges) and the distance separating implants from cells in the region carrying oestradiol receptors. These results show that the mediobasal hypothalamus is a site of action for the oestradiol-induced preovulatory GnRH surge in the ewe. Immunohistochemical tests should identify the nature of the cells forming the relay for the steroid action.

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Documento generato il 29/11/20 alle ore 18:34:33