The in vitro effects of cyclic nucleotides, cyanoketone, and cycloheximide on the production of estradiol-17β by vitellogenic ovarian follicles of goldfish (Carassius auratus)

Abstract

The effects of human chorionic gonadotropin (HCG), forskolin, cyclic nucleotides, the phosphodiesterase inhibitors IBMX and theophylline, cyanoketone, and cycloheximide on the production of estradiol-17β by isolated ovarian follicles of vitellogenic goldfish (Carassius auratus) were examined using 18-hr incubations. HCG and all test agents which are known to increase intracellular concentrations of cAMP significantly stimulated the production of estradiol-17β. However, dibutyryl cGMP was unable to stimulate estradiol-17β production at any concentration used (1–10 mM). Cyanoketone at a concentration of 1 μg/ml completely blocked forskolin-induced estradiol-17β production. Even in the presence of cyanoketone, however, forskolin stimulated conversion of exogenous testosterone to estradiol-17β in a dose-dependent manner, suggesting the involvement of an adenylate-cyclase system in the induction of aromatase activation by vitellogenic follicles of goldfish. Cycloheximide also completely abolished HCG-induced estradiol-17β production when this inhibitor was added within the first 1 hr after the addition of HCG. These results provide evidence that the stimulation of estradiol-17β by goldfish vitellogenic follicles in response to HCG is dependent upon the synthesis of new protein.