The role of cyclic AMP in the induction of estrogen and progestin synthesis in cultured granulosa cells.

The role of cyclic AMP in the induction of enzymes involved in estrogen and progestin biosynthesis in undifferentiated granulosa cells was investigated. When granulosa cells from immature hypophysectomized, DES-treated rats were cultured for 2 days in serum-free medium with aromatase substrate (10(-7) M androstenedione) together with graded doses of FSH, prostaglandin E2 (PGE2), cholera toxin (CT), or dibutyryl cyclic AMP (Bu2cAmP), there was a dose-related increase in estrogen (E) production. The induction of E production by saturating doses of FSH, PGE2, CT, and Bu2cAmP required a lag phase of approximately 24 h, after which the E response increased sharply to maximum levels at day 3, and then declined gradually to day 5. Treatment for 24 h ((day 0-1) with FSH, together with 1 microgram/ml of either actinomycin D or cycloheximide, completely abolished the stimulatory action of FSH on E production. When the inhibitors were removed, the FSH-induced increases in E returned to near normal levels after a 24-h lag period. Similar effects of the inhibitors upon E production by CT, PGE2 and Bu2cAMP were observed. As with E, the production of progesterone and 20 alpha-dihydroprogesterone was markedly stimulated by FSH, PGE2, CT and Bu2cAmP, and the results of the time course, dose response, and inhibitor experiments were similar to those for E production. These results indicate that FSH induces the de novo synthesis of enzymes required for both estrogen and progestin biosynthesis by undifferentiated granulosa cells and suggest that this action is mediated by cyclic AMP.