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Titolo:
THE REGULATION OF GONADOTROPIN-RELEASING HORMONE-INDUCED CALCIUM SIGNALS IN MALE-RAT GONADOTROPHS BY TESTOSTERONE IS MEDIATED BY DIHYDROTESTOSTERONE
Autore:
TOBIN VA; CANNY BJ;
Indirizzi:
MONASH UNIV,DEPT PHYSIOL CLAYTON VIC 3168 AUSTRALIA MONASH UNIV,DEPT PHYSIOL CLAYTON VIC 3168 AUSTRALIA
Titolo Testata:
Endocrinology
fascicolo: 3, volume: 139, anno: 1998,
pagine: 1038 - 1045
SICI:
0013-7227(1998)139:3<1038:TROGHC>2.0.ZU;2-R
Fonte:
ISI
Lingua:
ENG
Soggetto:
ANTERIOR-PITUITARY-CELLS; FOLLICLE-STIMULATING-HORMONE; GONADAL-STEROID MODULATION; MESSENGER-RNA LEVELS; LUTEINIZING-HORMONE; LH-SECRETION; 5-ALPHA-REDUCTASE; INHIBITION; FINASTERIDE; ESTRADIOL;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
62
Recensione:
Indirizzi per estratti:
Citazione:
V.A. Tobin e B.J. Canny, "THE REGULATION OF GONADOTROPIN-RELEASING HORMONE-INDUCED CALCIUM SIGNALS IN MALE-RAT GONADOTROPHS BY TESTOSTERONE IS MEDIATED BY DIHYDROTESTOSTERONE", Endocrinology, 139(3), 1998, pp. 1038-1045

Abstract

The biological effects of testosterone (T) may be mediated directly by T or indirectly by its metabolites, dihydrotestosterone (DHT) and estradiol. The present study examined whether the metabolism of T is involved in the regulation of GnRH-induced Ca2+ signaling at the pituitary. In gonadotrophs from castrated rats, a significantly greater percentage of gonadotrophs demonstrated oscillatory Ca2+ responses to 100 nMGnRH than cells from intact rats (72% vs. 24%; P < 0.05). This increase was prevented by the administration of T propionate (0.1 mg/kg day), DHT benzoate (2 mg/kg day,), estradiol benzoate (EB; 5 mu g/kg day),or the combination of the above doses of DHT benzoate and EB. In all cases the proportion of gonadotrophs hom the steroid treated rats having oscillatory Ca2+ responses to 100 nM GnRH was between 21-25% (P > 0.05, compared with intact rats). To assess the importance of T metabolism, intact male rats were treated with the aromatase inhibitor letrozole (1 mg/kg day), the 5 alpha-reductase inhibitor finasteride (50 mg/kg day), or their respective vehicles for 7 days. Letrozole had no effect on GnRH-induced Ca2+ signals, serum LH concentrations, or ventral prostate or testes weight. Finasteride treatment, however, mimicked the effects of castration, with significantly more gonadotrophs exhibiting Ca2+ oscillations in response to 100 nM GnRH than gonadotrophs fromthe vehicle-treated group (71% vs. 20% respectively; P < 0.05). Finasteride also caused a significant (P < 0.05) decrease in prostatic weight and DHT concentration, but had no significant effect on either prostatic T or serum LH concentrations. These findings suggest that in theintact male rat, the effects of T on GnRH-induced Ca2+ signaling are preferentially mediated via DHT. The results of this study also show that in the absence of androgens, estradiol may regulate GnRH-induced Ca2+ signaling in the male rat pituitary.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 30/09/20 alle ore 09:28:00