Melatonin role in ovarian function

Melatonin is a hormone mainly produced by the pineal gland in the absence of light stimuli. The light, in fact, hits the retina, which sends a signal to the suprachiasmatic nucleus which inhibits the synthesis of the hormone by the epiphysis. Mostly by interacting with MT1/MT2 membrane receptors, melatonin performs various physiological actions, among which the regulation of the sleep-wake cycle and the control of the immune system. One of its best known functions is the non-enzymatic antioxidant action, which is independent from binding with receptors and occurs by electron donation. The hormone also represents an indicator of the photoperiod in seasonally reproducing mammals, which are divided into long days and short days breeders according to the time of year in which they are sexually active and fertile. It is known that melatonin acts at hy-pothalamic pituitary gonadal axis level in many species. In particular, it inhibits the hypothalamic release of GnRH with consequent alteration of FSH and LH levels. Present paper is mainly ad-dressed to review the ovarian effect of melatonin.