[Regulation of aromatase activity by gonadotropin-releasing hormone and its agonists in cultured rat granulosa cells].

The effects of Gn-RH and its agonists on the activity of aromatase were examined by means of a rat granulosa cell culture system. A potent Gn-RH agonist, buserelin ([D-Ser (but)6 des-Gly-NH2(10)] Gn-RH ethylamide), alone stimulated aromatase activity in a dose-dependent manner at concentrations between 10(-13) and 10(-6) M. Both Gn-RH and another Gn-RH agonist, TAP144 ([D-Leu6, des-Gly-NH2(10)] Gn-RH ethylamide), also exhibited a stimulatory effect. Buserelin enhanced the activity of aromatase stimulated by FSH at concentrations of 1 and 10 ng/ml. However, it decreased the activity stimulated by a higher level of FSH (100 ng/ml). These results indicate that Gn-RH agonist increases the activity of aromatase in the absence of FSH. However, in the presence of FSH it exerts different effects on the aromatase activity depending on the concentrations of FSH.