Melatonergic System Melatonin not only regulates the circadian phase [75], but also acts as a hypnotic, is an effective free-radical scavenger and antioxidant, and directly induces gonadotropin-inhibitory hormone expression [76]. Interestingly, bright light during nighttime decreases melatonin secretion [77]. The existence of immunoreactivity against melatonin was demonstrated in the bacterium Rhodospirillum rubrum, one of the […]