Gonadotrophin-releasing hormone and triptorelin inhibit the follicle stimulating hormone-induced response in human primary cultured granulosa-lutein cells.

Cyclic AMP (c-AMP)-dependent cell shape changes can be used to study the gonadotrophin response in cultured human granulosa-lutein cells. The same approach has been developed here to determine the direct potential antigonadotrophic effect of gonadotrophin-releasing hormone (GnRH) and a GnRH agonist (triptorelin) on human granulosa-lutein cells. Treatment with triptorelin or GnRH alone for 1 h did not affect granulosa-lutein cell morphology. However, in the presence of stimulatory doses of follicle stimulating hormone (FSH), triptorelin (5 x 10(-7)-5 x 10(-6) M) and GnRH (10(-11)-10(-9) M) inhibited the FSH-induced c-AMP-dependent response. The antigonadotrophic effect of triptorelin was prevented by two GnRH antagonists, indicating that triptorelin acts via specific GnRH binding sites. On the other hand, triptorelin failed to inhibit human chorionic gonadotrophin- and forskolin-mediated morphological changes. Our results suggest that the GnRH agonist interacts specifically with the FSH-induced c-AMP-dependent cascade of events, at a site located ahead of that of c-AMP generation. In conclusion, GnRH and triptorelin strongly inhibit FSH-mediated function in human granulosa-lutein cells in culture. This inhibition might play a role in the low follicular development rates observed in some patients treated with GnRH agonist + gonadotrophins for ovarian stimulation.