Objective: To test the hypothesis that melatonin modulates steroid synthesis in the human ovary.
Design: Granulosa lutein cells obtained from in vitro fertilization cycles were cultured in medium containing melatonin and human chorionic gonadotropin (hCG).
Results: Progesterone (P) secretion by granulosa lutein cells increased progressively in both basal and hCG-stimulated conditions, up to 96 hours in culture, plateaued at 144 and decreased thereafter. Melatonin (10(-7), 10(-9), 10(-11) M) had no effect on basal P or 17 beta-estradiol production. The addition of melatonin to the hCG-treated granulosa lutein cells significantly (P less than 0.05) potentiated the stimulatory effect of hCG on P production. The effect was most prominent after 144 and 196 hours of incubation.
Conclusion: This observation suggests a role for melatonin in the intraovarian control of P production in the human ovary.