Insulin as an Amplifier of Gonadotropin Action on Steroid Production: Mechanisms and Sites of Action in Goldfish Prematurational Full-Grown Ovarian Follicles

The present study examines the effects of mammalian insulin and insulin-like growth factor-I (IGF-I) on steroid production by goldfish vitellogenic and prematurational full-grown ovarian follicles in vitro. Insulin (0.4-40 micrograms/ml) had no effect on its own, but potentiated human chorionic gonadotropin (hCG) and 25-hydroxycholesterol-stimulated testosterone production by prematurational full-grown follicles in both a dose- and …