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Titolo:
Progesterone and testosterone in combination act in the hypothalamus of castrated rams to regulate the secretion of LH
Autore:
Turner, AI; Tilbrook, AJ; Clarke, IJ; Scott, CJ;
Indirizzi:
Monash Univ, Dept Physiol, Monash, Vic 3800, Australia Monash Univ MonashVic Australia 3800 hysiol, Monash, Vic 3800, Australia Prince Henrys Inst Med Res, Clayton, Vic 3168, Australia Prince Henrys Inst Med Res Clayton Vic Australia 3168 Vic 3168, Australia
Titolo Testata:
JOURNAL OF ENDOCRINOLOGY
fascicolo: 2, volume: 169, anno: 2001,
pagine: 291 - 298
SICI:
0022-0795(200105)169:2<291:PATICA>2.0.ZU;2-L
Fonte:
ISI
Lingua:
ENG
Soggetto:
GONADOTROPIN-RELEASING-HORMONE; RECEPTOR MESSENGER-RNA; LUTEINIZING-HORMONE; GUINEA-PIG; SEX-DIFFERENCES; PREOPTIC AREA; ESTROGEN-RECEPTOR; SEASONAL-CHANGES; GENE-EXPRESSION; SUPPRESSION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
36
Recensione:
Indirizzi per estratti:
Indirizzo: Turner, AI Monash Univ, Dept Physiol, POB 13F, Monash, Vic 3800, AustraliaMonash Univ POB 13F Monash Vic Australia 3800 c 3800, Australia
Citazione:
A.I. Turner et al., "Progesterone and testosterone in combination act in the hypothalamus of castrated rams to regulate the secretion of LH", J ENDOCR, 169(2), 2001, pp. 291-298

Abstract

We tested the hypotheses that progesterone enhances the negative feedback actions of testosterone in rams and that this occurs through actions at thehypothalamus. In the first part of this study, blood samples were collected every 10 min for 12 h before and after 7 days of treatment (i.m.) of castrated Romney Marsh rams (n=5 per group) with vehicle, progesterone (4 mg/12h), testosterone (4 mg/12 h) or a combination of progesterone (4 mg/12 h) and testosterone (4 mg/12 h). In the second part of this study the: brains of four gonad-intact Romney Marsh rams were collected, the hypothalamus wassectioned and in situ hybridisation of mRNA for progesterone receptors conducted. After 7 days of treatment with vehicle or progesterone or testosterone alone, there were no changes in the secretion of LH, In contrast. treatment with a combination of progesterone and testosterone resulted in a significant (P <0.01, repeated measures ANOVA) decrease in mean plasma concentrations of LH, the number of LH pulses per hour and the pre-LH pulse nadir and a significant (P <0.01) increase in the inter-LH pulse interval. We found cells containing mRNA for progesterone receptors throughout the hypothalamus, including the preoptic area (where most GnRH neurons are located in sheep), the periventricular, ventromedial and arcuate nuclei and the bed nucleus of the stria terminalis. This study shows that progesterone is capable of acting centrally with testosterone to suppress the secretion of LH ill castrated rains and that cells containing mRNA for progesterone receptors are located ill the hypothalamus of rams in the vicinity of GnRH neurons.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 19/09/20 alle ore 09:17:34