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Titolo:
FEEDBACK ACTIONS OF ESTRADIOL ON GNRH SECRETION DURING THE FOLLICULARPHASE OF THE ESTROUS-CYCLE
Autore:
KARSCH FJ; EVANS NP;
Indirizzi:
UNIV MICHIGAN,REPROD SCI PROGRAM,300 N INGALLS BLDG ANN ARBOR MI 48109 UNIV MICHIGAN,DEPT PHYSIOL ANN ARBOR MI 48109 BABRAHAM RES INST,DEPT NEUROBIOL CAMBRIDGE CB2 4AT ENGLAND
Titolo Testata:
Acta Neurobiologiae Experimentalis
fascicolo: 3, volume: 56, anno: 1996,
pagine: 715 - 725
SICI:
0065-1400(1996)56:3<715:FAOEOG>2.0.ZU;2-J
Fonte:
ISI
Lingua:
ENG
Soggetto:
GONADOTROPIN-RELEASING-HORMONE; PULSE-GENERATOR ACTIVITY; OVARIECTOMIZED EWES; LH SURGE; (LH)-RELEASING HORMONE; MEDIAN-EMINENCE; GENE-EXPRESSION; RHESUS-MONKEY; NEURONS; HYPOTHALAMUS;
Keywords:
POSITIVE FEEDBACK; NEGATIVE FEEDBACK; LH SURGE; GNRH SURGE; LH PULSES; GNRH PULSES; OVULATION;
Tipo documento:
Review
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
35
Recensione:
Indirizzi per estratti:
Citazione:
F.J. Karsch e N.P. Evans, "FEEDBACK ACTIONS OF ESTRADIOL ON GNRH SECRETION DURING THE FOLLICULARPHASE OF THE ESTROUS-CYCLE", Acta Neurobiologiae Experimentalis, 56(3), 1996, pp. 715-725

Abstract

The pattern of GnRH secretion during the follicular phase of the estrous cycle of sheep is characterized by an initial marked change in episodic secretion (increased frequency and decreased amplitude) followedby a massive and sustained discharge - the preovulatory GnRH surge. Studies employing a physiological model for the follicular phase have revealed that estradiol has profound and complex feedback effects on GnRH release during the preovulatory period. These include both quantitative effects on pulses (stimulation of frequency, inhibition of amplitude) and qualitative effects (altering pulse shape, stimulating interpulse secretion), in addition to inductng a preovulatory GnRH surge. Instimulating the surge, estradiol causes a highly characteristic change in the minute-to-minute pattern of GnRH in hypophyseal portal blood. Initially, a strictly episodic pattern gives way to one in which GnRHis consistently elevated between pulses. Then, following enhancement of both pulsatile and interpulse components, GnRH becomes extremely high and variable for the majority of the surge. From this point, a regular and well organized pulse pattern is not apparent. The characteristic time course of GnRH at surge onset provides insight into possible mechanistic changes in the GnRH neurosecretory system. Such changes include quantitative and qualitative alterations in the pulse generating mechanism, recruitment of a surge specific population of GnRH neurones, morphologic alterations in GnRH neurones and neighboring cells, and changes in efficiency or route of delivery of GnRH from its site of release to the portal vasculature. These possibilities, while untested and speculative, provide a conceptual framework for future research.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 29/11/20 alle ore 18:02:56