Melatonin and the ovary: physiological and pathophysiological implications

Objective: To summarize the role of melatonin in the physiology and pathophysiology of the ovary. Design: Review of literature. Setting: University Health Science Center. Result(s): Melatonin plays an essential role in the pathogenesis of many reproductive processes. Human preovulatory follicular fluid (FF) contains higher concentrations of melatonin than does plasma, and melatonin receptors are present in ovarian granulosa cells (GC). Melatonin has been shown to have direct effects on ovarian function. Reactive oxygen species and apoptosis are involved in a number of reproductive events including folliculogenesis, follicular atresia, ovulation, oocyte maturation, and corpus luteum (CL) formation. Melatonin and its metabolites are powerful antioxidants; the primitive and primary function of melatonin may be its actions as a receptor-independent free radical scavenger and a broad-spectrum antioxidant. A large amount of scientific evidence supports a local role of melatonin in the human reproductive processes. The indole also has potential roles in the pathophysiology of endometriosis, polycystic ovary syndrome (PCOS), and premature ovarian failure (POF). Conclusion(s): We summarize the current understanding of melatonin's essential functions in the human ovary. Melatonin could become an important medication for improving ovarian function and oocyte quality, and open new opportunities for the management of several ovarian diseases.