Melatonin and its Receptors

Background: Melatonin (5-methoxy-N-acetyltryptamine) is a hormone that has numerous physiological functions. Synthesized and released during nighttime, melatonin exerts its physiological effects in a circadian manner. Melatonin acts by binding to its different types of receptors. The purpose of this systematic review is to summarize recent findings about melatonin, its receptors, and the differential functionalities of the most characterized melatonin receptors MT1 and MT2. Methods: We searched PubMed and Google Scholar for studies that reported melatonin receptor subtypes, their differential functionalities, biochemical structures, signal transductions, and various functions of melatonin such as pain, sleep, temperature, and antioxidative effects. We chose seventy articles for this systematic review. Summary: These studies highlight melatonin’s range of physiological functions and the differential functionalities of the melatonin receptors MT1 and MT2; they characterize the receptors’ signal transduction cascades and their biochemical structures. More studies assessing melatonin receptors’ functions would help patients with disorders in sleep, pain, and circadian rhythm.