Melanotan II (MT2) is a synthetic analogue of the peptide hormone a-melanocyte-stimulating hormone (a-MSH).Melanotan II acts as a non-selective agonist of the melanocortin receptors MC1, MC3, MC4, and MC5. In universe studies it is shown to the extent that melanotan II produces melanogenesis, this is thought to be activation of the MC1 receptor, whereas its research data in rats documented sexual induced effects are thought to be related to its ability to activate the MC4 receptor (through the MC3 is thought to possible also be involved).