Melanotan II

Melanotan II (MT2) is a synthetic melanocortin receptor agonist and analogue of alpha-melanocyte-stimulating hormone (a-MSH), the endogenous 13-amino acid melanocortin peptide. MT2 is a non-selective agonist active across the melanocortin receptor family (MC1R-MC5R), a family of five class A G protein-coupled receptors that mediate diverse biological effects through Galphas/cAMP signalling. At MC1R (expressed on melanocytes), MT2 activation stimulates melanogenesis: cAMP activation triggers the microphthalmia-associated transcription factor (MITF) pathway, upregulating tyrosinase and other melanogenic enzymes that convert tyrosine to melanin via the eumelanin and pheomelanin pathways. This MC1R-mediated melanogenesis is the basis for MT2's pigmentation research applications. At MC3R and MC4R (expressed in the hypothalamus), MT2 activates central melanocortin signalling pathways that regulate appetite and energy homeostasis: MC4R activation suppresses appetite through POMC/CART neuropeptide pathway signalling, while MC3R modulates energy partitioning and feeding behaviour. At MC5R (expressed in exocrine glands), MT2 influences sebaceous gland activity. The broad receptor activity across MC1R-MC5R makes MT2 a versatile research tool for studying the full melanocortin receptor family and the diverse physiological pathways they regulate.