Effect of a gonadotropin-releasing hormone agonist on luteinizing hormone receptors and steroidogenesis in ovarian cells

To examine the effect of a gonadotropin-releasing hormone agonist (GnRH-a), leuprolide acetate (LA), on human chorionic gonadotropin/luteinizing hormone (LH) receptors content and progesterone (P) and estradiol (E2) production in cultured granulosa or luteal cells. Prospective. Private Fertility Clinic and National Research Institute. Twenty patients undergoing in vitro fertilization or gamete intrafallopian transfer programs. Human chorionic gonadotropin/LH receptors in human granulosa cells increased after 48hours of culture, and LA inhibited such effect. Leuprolide acetate, 1ng/mL, in the cultures produced an increase in P production. On the contrary, LA inhibited E2 production. Additionally, the in vivo effect of LA (2μg/rat per 7days) was studied in corpus luteum of superovulated rats. Luteal cells from LA-treated rats in culture produced lower P than the controls but showed an increase in aromatase activity. Luteal LH receptors declined after 48hours of culture with LA. The high doses of gonadotropin necessary to induce ovarian hyperstimulation when GnRH-a is administered could be related with an inhibitory effect of these agonists on LH receptors and aromatase activity.