Melatonin Receptor Antibodies

The melatonin receptor family consists primarily of the G protein-coupled receptors MT₁ and MT₂, which mediate the physiological effects of the hormone melatonin on circadian rhythm regulation and sleep–wake timing. Pharmacologically, these receptors are activated by endogenous melatonin as well as by clinically used agonists such as ramelteon, agomelatine, and tasimelteon, which are employed in the treatment of insomnia and circadian rhythm sleep disorders. Upon ligand binding, melatonin receptors mainly couple to Gi/o proteins, leading to inhibition of adenylate cyclase, reduced intracellular cyclic AMP levels, and modulation of downstream signaling pathways that influence neuronal excitability and clock gene expression. Additional signaling mechanisms may include regulation of phospholipase C activity, ion channel function, and MAP kinase pathways, contributing to neuroprotective and antidepressant-like effects. MT₁ and MT₂ receptors are highly expressed in the suprachiasmatic nucleus of the hypothalamus, the central circadian pacemaker, but are also found in the retina, pituitary gland, immune cells, and peripheral metabolic tissues. This widespread expression supports roles in sleep regulation, seasonal physiology, immune modulation, and metabolic homeostasis. Owing to their central function in circadian timing and sleep control, melatonin receptors represent important therapeutic targets for chronobiological and neuropsychiatric disorders.