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Titolo:
A CENTRAL NEGATIVE FEEDBACK ACTION OF THYROID-HORMONES ON THYROTROPIN-RELEASING-HORMONE SECRETION
Autore:
DAHL GE; EVANS NP; THRUN LA; KARSCH FJ;
Indirizzi:
UNIV MICHIGAN,REPROD SCI PROGRAM,300 N INGALLS BLDG,ROOM 1101 SW ANN ARBOR MI 48109 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:
Endocrinology
fascicolo: 6, volume: 135, anno: 1994,
pagine: 2392 - 2397
SICI:
0013-7227(1994)135:6<2392:ACNFAO>2.0.ZU;2-Q
Fonte:
ISI
Lingua:
ENG
Soggetto:
HYPOPHYSEAL PORTAL BLOOD; MEDIAN-EMINENCE; TRH; HYPOTHYROIDISM; PROLACTIN; EWES; RAT; LH;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
26
Recensione:
Indirizzi per estratti:
Citazione:
G.E. Dahl et al., "A CENTRAL NEGATIVE FEEDBACK ACTION OF THYROID-HORMONES ON THYROTROPIN-RELEASING-HORMONE SECRETION", Endocrinology, 135(6), 1994, pp. 2392-2397

Abstract

Two experiments were conducted to test the hypothesis that thyroid hormones exert central negative feedback effects on the secretion of TRHfrom the hypothalamus in the ewe. In the first experiment, we examined the effects of thyroidectomy on the secretion of TRH and TSH. Thyroidectomy was followed by an unambiguous increase in TRH in pituitary portal plasma and TSH in the peripheral circulation. In the second experiment, we tested the effects of T-4 replacement to thyroidectomized ewes. T-4 replacement reversed the effects of thyroidectomy on TRH and TSH release. Of interest, TRH secretion in thyroidectomized ewes was continuously elevated during the collection, raising the possibility that TRH is secreted continuously, rather than exclusively in a strictly pulsatile manner indicative of phasic discharges synchronized among TRH neurosecretory elements. Collectively, these results suggest that thyroid hormones can act centrally to inhibit TRH (and thus TSH) releasein the ewe, and they support the concept that at least part of the negative feedback action of thyroid hormones is exerted at the hypothalamic level.

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Documento generato il 26/11/20 alle ore 14:30:30