Melanotan-2 and Melanocortin Receptor Agonism
Non-selective melanocortin agonist studied for pigmentation pathways and MC4R-mediated behavior.
- 1Non-selective agonist of MC1R, MC3R, MC4R, and MC5R.
- 2MC1R activation upregulates eumelanin synthesis in melanocytes.
- 3MC3R/MC4R activity modulates appetite and sexual-behavior circuits.
- 4Selective successors (PT-141, afamelanotide) were developed to narrow the receptor profile.
A Non-Selective Melanocortin Agonist
Melanotan-2 (MT-2) is a synthetic cyclic analog of α-MSH that activates multiple melanocortin receptors — MC1R, MC3R, MC4R, and MC5R. Its non-selectivity is both its mechanistic appeal in research and the reason its effects are broader than later selective agonists like bremelanotide (PT-141, MC4R-biased) or afamelanotide (MC1R-biased).
MC1R and Pigmentation
MC1R activation on melanocytes upregulates eumelanin synthesis. In rodent and cell-culture models MT-2 reliably increases tyrosinase activity and melanin output, and human case-series describe darkening of skin and existing nevi — the most consistently reported observation in the literature.
MC3R / MC4R Central Effects
Central MC3R and MC4R activity is associated with appetite suppression and modulation of sexual-behavior circuits in rodent paradigms — observations that motivated the development of the MC4R-selective successor PT-141. Off-target effects reported with MT-2 (nausea, flushing, blood-pressure shifts) are attributable to its broad melanocortin engagement rather than any single receptor.
