Melanotan II is a synthetic cyclic analogue of alpha-melanocyte-stimulating hormone (α-MSH), a non-selective agonist at melanocortin receptors MC1R, MC3R, MC4R, and MC5R. Developed by researchers at the University of Arizona, it has been studied for its effects on skin pigmentation, energy homeostasis, and as the precursor compound from which bremelanotide (PT-141) was derived. Below is a curated selection of peer-reviewed studies investigating its properties.
2021
Melanocortin Receptor Agonists: A New Generation of Anti-Obesity Drugs
PMC / Frontiers in Endocrinology
This review examines the role of MC4R-targeting melanocortin agonists — including Melanotan II — in energy balance regulation. MC4R activation in the hypothalamus suppresses appetite and increases energy expenditure. The review covers the pathway from early MT-II research to the development of selective MC4R agonists and their implications for obesity research.
View Paper →2019
Melanocortin Receptors, Melanotropic Peptides and Penile Erection
PMC / Current Topics in Medicinal Chemistry
This review covers the role of melanocortin receptors in sexual function, documenting how MT-II and related peptides activate MC3R and MC4R in the brain to produce pro-erectile effects independent of vascular pathways. Melanotan II human studies demonstrated erections in 17 of 20 men with erectile dysfunction, alongside increased sexual desire.
View Paper →2009
MC1R Variants, Melanoma and Skin Cancer: Current Status and Future Challenges
PMC / Pigment Cell & Melanoma Research
This study examines the relationship between MC1R signalling, eumelanin production, and UV-induced DNA damage. It documents how MC1R activation — as stimulated by α-MSH analogues including MT-II — drives photoprotective eumelanin synthesis and upregulates DNA repair pathways, providing mechanistic context for the pigmentation research applications of melanocortin agonists.
View Paper →2005
Double-Blind Placebo-Controlled Evaluation of the Safety, Pharmacokinetics and Pharmacodynamic Effects of Subcutaneously Administered Melanotan II
PubMed / International Journal of Impotence Research
This controlled human pharmacokinetic study characterised the safety and dose-response profile of subcutaneous Melanotan II administration. The study documented predictable GH release, skin pigmentation induction, and dose-dependent effects on sexual arousal, providing key early clinical data on Melanotan II’s systemic activity in humans.
View Paper →2003
PT-141: A Melanocortin Agonist for the Treatment of Sexual Dysfunction
Annals of the New York Academy of Sciences
This paper documents the development of PT-141 (bremelanotide) directly from Melanotan II research, detailing how MT-II’s melanocortin receptor activity in the CNS led to the identification of a CNS-acting sexual function pathway. PT-141 was subsequently approved by the FDA in 2019 as Vyleesi for hypoactive sexual desire disorder.
View Paper →2000
Melanocortin Receptor Agonists, Penile Erection, and Sexual Motivation: Human Studies with Melanotan II
PubMed / International Journal of Impotence Research
This foundational human study of Melanotan II in men with erectile dysfunction demonstrated robust penile erections (average 38 minutes at >80% rigidity) via melanocortin receptor activation, independent of vascular mechanisms. The findings directly initiated the research pathway that led to the FDA-approved bremelanotide.
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