IN-VITRO APPLICATION OF TESTOSTERONE POTENTIATES GONADOTROPIN-RELEASING HORMONE-STIMULATED GONADOTROPIN-II SECRETION FROM CULTURED GOLDFISHPITUITARY-CELLS

Authors
Citation
A. Lo et Jp. Chang, IN-VITRO APPLICATION OF TESTOSTERONE POTENTIATES GONADOTROPIN-RELEASING HORMONE-STIMULATED GONADOTROPIN-II SECRETION FROM CULTURED GOLDFISHPITUITARY-CELLS, General and comparative endocrinology (Print), 111(3), 1998, pp. 334-346
Citations number
54
Categorie Soggetti
Endocrynology & Metabolism
ISSN journal
00166480
Volume
111
Issue
3
Year of publication
1998
Pages
334 - 346
Database
ISI
SICI code
0016-6480(1998)111:3<334:IAOTPG>2.0.ZU;2-P
Abstract
The in vitro effects of overnight treatment with testosterone (T) on g onadotropin (GTH)-II secretion from primary cultures of dispersed fema le goldfish pituitary cells were examined. T (100 nM) did not affect b asal GTH-II release, but increased GTH-II responses to initial applica tions of 0.5-h pulses of sGnRH or cGnRH-II in cells from females at se xually regressed, recrudescing, or mature (prespawning) stages. Pretre atment with 10 nM T was also effective, except in experiments with cel ls from sexually regressed females. Analysis of GTH-II response profil es to the first GnRH pulse revealed that T increased the size of the i nitial (first 15 min) and sustained (rest of response) release phases, and the duration of the total response to both GnRHs. These results i ndicate that direct positive influence of T on GnRH-stimulated GTH-II release is demonstrable in cells from female goldfish at all ovarian m aturational stages; in addition, T affects both the initial and the su stained response phases. Howe-c er, compared to the initial GnRH chall enge, responses to a second 0.5-h GnRH pulse were decreased in T-treat ed but not in control cells, suggesting that T also enhanced desensiti zation. Ovarian maturational conditions modulated the effects of T on the GTH-II response kinetics. In cells prepared from sexually regresse d females, T treatment changed the ''monophasic'' (initial phase only) GTH-II response to sGnRH to a ''biphasic'' one characteristic of cell s prepared from fish at later stages of gonadal recrudescence. Advanci ng gonadal maturity increased the magnitude of both initial and sustai ned phases of the T-enhanced GTH-IZ response to sGnRH, but only elevat ed the initial phase of T-potentiated cGnRH-II-induced release. Direct actions of T on pituitary cells may play a role in ovarian steroid fe edback regulation of GTH-II secretion during the seasonal reproductive cycle in goldfish. (C) 1998 Academic Press.