Stimulation of androstenedione and progesterone release by LHRH and LHRH agonist from isolated rat preovulatory follicles.

Incubation of preovulatory rat follicles isolated from PMSG-treated immature rats for periods of less than 24 h in the presence of LHRH or LHRH agonist resulted in stimulation of basal androstenedione and progesterone release. The stimulatory effects seen were time-dependent, occurring from 2-3 h for androstenedione and from 8-20 h incubation for progesterone. Dose-dependent stimulation occurred with both LHRH agonist (in the range 5 X 10(-10) to 10(-8) M) and native LHRH (from 10(-9) to 10(-6) M), both being in the range of the reported Ka for ovarian LHRH receptors. LHRH did not enhance the stimulatory effect of 1-100 mIU hCG on androstenedione and progesterone release. These results show for the first time that LHRH and LHRH agonist can exert a stimulatory action on androgen release from isolated preovulatory follicles. This suggests that LHRH may be acting either directly at the thecal cell level or indirectly via decreased granulosa cell aromatization.