Increased endogenous level of melatonin in preovulatory human follicles does not directly influenced progesterone production

Objective: To study the role of follicular melatonin on steroid production by human preovulatory follicles. Design: In vivo comparative and in vitro culture studies. Setting: University hospital. Patient(s): Thirty-six patients with tubal and/or male, but not endocrinological, infertility factors. Intervention(s): Follicular fluid collection during IVF. In vitro granulosa cell culture from luteinizing or growing Graafian follicles. Main Outcome Measure(s): Follicular melatonin, P, T, and E-2 concentrations. In vitro P production by granulosa cells. Result(s): There was a positive correlation between follicular melatonin and P concentrations. Melatonin did not stimulate in vitro P production by granulosa cells from luteinizing or growing follicles. Melatonin, P, and E, concentrations were significantly higher, but T concentrations were lower, in large follicles than in small follicles. Conclusion(s): Preovulatory follicles contain a high amount of melatonin compared with that in small immature follicles; melatonin may play an important, but indirect, role in P production by human granulosa cells. ((C)2003 by American Society for Reproductive Medicine).