Melanotan II is a synthetic cyclic heptapeptide analogue of α-MSH with broader melanocortin receptor activity than Melanotan I, acting on MC1R, MC3R, MC4R, and MC5R. Its MC1R activity drives melanogenesis and skin pigmentation, while its MC4R activation in the central nervous system has been associated with sexual arousal and appetite suppression effects studied in preclinical models. This broader receptor profile makes Melanotan II a compound of interest across aesthetic, vitality, and neuroendocrine research. Its effects on sexual function have been particularly well documented in research models of both male and female libido.