Melanotan I vs Melanotan II | MC1R Selectivity Research Comparison | QSC
Melanotan I vs Melanotan II — Melanocortin Research Comparison
Melanotan I and Melanotan II are both synthetic alpha-MSH analogues — but with critically different receptor selectivity profiles. Melanotan I is MC1R-selective (melanogenesis only); Melanotan II activates MC1R, MC3R, and MC4R (melanogenesis + libido + appetite effects). The receptor selectivity difference is the key variable for research design.
MC4R — why it changes the research picture entirely
MC4R in the hypothalamus (particularly PVN and mPOA) mediates appetite suppression and sexual arousal. Melanotan II activates MC4R alongside MC1R — meaning any MT-II experiment combines melanogenesis + appetite + sexual function effects simultaneously. For pure melanogenesis research, this is a major confound. Melanotan I (MT-I) provides MC1R-only melanogenesis without these CNS MC4R effects — making it the cleaner tool for cutaneous pigmentation research.
When to choose MT-II despite broader receptor activation
If the research question involves studying MC4R (libido, penile erection, appetite suppression) in the same experiment as melanogenesis — or if studying combined melanocortin receptor pharmacology — MT-II is the appropriate compound. MT-II + MC4R antagonist (SHU9119) allows dissection of MC1R vs MC4R contributions to any observed effect.
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Frequently Asked Questions
What is the primary research difference between Melanotan I and Melanotan II?
MC1R selectivity. Melanotan I activates MC1R (melanogenesis) without significant MC4R activity. Melanotan II activates MC1R + MC3R + MC4R — adding libido (MC4R, mPOA), appetite suppression (MC4R, PVN), and systemic melanocortin effects. For clean melanogenesis research, MT-I is preferred.
Is Melanotan I FDA approved?
Afamelanotide (Melanotan I) is approved in the EU for erythropoietic protoporphyria (EPP) under the brand name Scenesse. It is not FDA approved in the US. QSC supplies Melanotan I as a research compound only.
Can Melanotan I and Melanotan II be used together?
Combining MT-I and MT-II would add MT-I MC1R activity to MT-II MC1R/MC3R/MC4R — not providing independent mechanistic insight. More useful is MT-II with selective MC4R antagonists (SHU9119) or MC1R antagonists (AGRP) to isolate receptor contributions.
