💊Melanotan II
Non-selective melanocortin receptor agonist (MC1R–MC5R). Precursor to PT-141 (bremelanotide). Promotes melanogenesis, sexual arousal, and appetite suppression. Extensive preclinical and human data.
Cyclic Ac-Nle-c[Asp-His-D-Phe-Arg-Trp-Lys]-NH₂What Is Melanotan II?
Melanotan II (MT-II) is a synthetic cyclic analogue of alpha-MSH, developed at the University of Arizona as a potential tanning agent. It is a non-selective agonist at MC1R, MC3R, MC4R, and MC5R. PT-141 (bremelanotide) is a metabolite of MT-II with the carboxyl group restored.
Key Mechanisms
- MC1R agonism — stimulates melanin production in melanocytes (tanning without UV)
- MC3R/MC4R agonism — initiates sexual arousal via hypothalamic dopamine pathways
- MC4R appetite suppression — reduces food intake via hypothalamic circuits
- MC5R activation — exocrine gland effects; sebaceous, lacrimal, and pancreatic secretion
Key References
- Wessells H et al. "Melanocortin receptor agonists, penile erection, and sexual motivation." Int J Impot Res, 2000;12(Suppl 4):S74–79.
Frequently Asked Questions
PT-141 (bremelanotide) is a metabolite of Melanotan II with the C-terminal amide replaced by a carboxyl group — it retains melanocortin activity but with a more MC4R/MC3R-selective profile, which is why PT-141 became an approved sexual-dysfunction treatment while MT-II research remains preclinical.
It's a non-selective agonist at MC1R, the melanocortin receptor subtype that drives melanogenesis in skin melanocytes — a direct, on-target effect of the mechanism being studied, not a side effect.
MC4R agonism in the hypothalamus — the same receptor subtype targeted by some anti-obesity drug candidates — is the basis for the appetite-suppression research interest in melanocortin agonists generally.