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Titolo:
INVOLVEMENT OF THYROID-HORMONES IN SEASONAL REPRODUCTION
Autore:
KARSCH FJ; DAHL GE; HACHIGIAN TM; THRUN LA;
Indirizzi:
UNIV MICHIGAN,REPROD SCI PROGRAM ANN ARBOR MI 48109 UNIV MICHIGAN,DEPT PHYSIOL ANN ARBOR MI 48109 UNIV MICHIGAN,DEPT BIOL ANN ARBOR MI 48109
Titolo Testata:
Journal of Reproduction and Fertility
, , anno: 1995, supplemento:, 49
pagine: 409 - 422
SICI:
0022-4251(1995):<409:IOTISR>2.0.ZU;2-X
Fonte:
ISI
Lingua:
ENG
Soggetto:
GONADOTROPIN-RELEASING-HORMONE; NEGATIVE FEEDBACK ACTION; STARLINGS STURNUS-VULGARIS; LUTEINIZING-HORMONE; PLASMA THYROXINE; BREEDING-SEASON; PHOTOPERIODIC CONTROL; PROLACTIN SECRETION; EWES; PHOTOREFRACTORINESS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
69
Recensione:
Indirizzi per estratti:
Citazione:
F.J. Karsch et al., "INVOLVEMENT OF THYROID-HORMONES IN SEASONAL REPRODUCTION", Journal of Reproduction and Fertility, 1995, pp. 409-422

Abstract

This article reviews experiments performed to investigate the importance of thyroid hormones to the expression of the seasonal reproductivecycle of ewes. Thyroidectomy was found to block the transition from the breeding season to anoestrus and to cause ewes to exhibit oestrous cycles all year round. Mechanistically, thyroidectomy produced this effect by preventing the seasonal increase in responsiveness to the negative feedback action of oestradiol on episodic GnRH secretion, thus interfering with a key neuroendocrine process necessary for anoestrus todevelop. This response to thyroidectomy was fully prevented by replacement with physiological concentrations of thyroxine. Furthermore, thereproductive response to thyroidectomy was specific to the mechanismsthat lead to anoestrus; other aspects of reproductive neuroendocrine function and seasonal and photoperiodic mechanisms were not affected. Evidence is presented to indicate that thyroid hormones have a permissive mode of action on seasonal reproduction, and that their effect is exerted during a restricted 'window' of time during the year. It is concluded that thyroid hormones play a crucial role of physiological significance to generation of the seasonal reproductive cycle of ewes.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 02/12/20 alle ore 07:47:57