Inhibition of human granulosa cell progesterone secretion by a gonadotropin-releasing hormone agonist.

A gonadotropin-releasing hormone (Gn-RH) agonist was found to inhibit the secretion of progesterone by cultured human granulosa cells in a dose-dependent manner. Significant inhibition was observed at agonist concentrations of 10-9M. A Gn-RH antagonist had no marked effect upon progestin secretion, but it prevented the inhibitory effects of the Gn-RH agonist. We conclude that Gn-RH-like substances can directly affect human granulosa cell function.