The effect of melatonin on steroidogenesis by the human ovary in vitro.

Melatonin stimulated steroidogenesis in two compartments of the human ovary in vitro. In a corpus luteum of the menstrual cycle, melatonin increased progesterone synthesis in a dose related manner. Both serotonin and N-acetyl serotonin had no effect on progesterone synthesis. In the ovarian stroma, melatonin stimulated the incorporation of acetate-1-14-C into androstenedione. Binding of radioactive hCG by the corpus luteum was unaffected by melatonin. No specific binding of radioactive melatonin of low specific activity could be detected in homogenates of a human corpus luteum. These observations suggest that melatonin may directly modulate steroidogenesis in the human ovary.