Function
While GHRP-6 is used experimentally to produce strong GH surges and hyperphagia, allowing investigation of GH-dependent anabolism and energy-balance regulation2030, Melanotan II is studied as a tanning and libido-enhancing agent; increases melanin production and can reduce food intake and modulate sexual arousal in animal models and humans3545.
Mechanism
While GHRP-6 works as a first-generation synthetic hexapeptide ghrelin mimetic that potently stimulates GH release and markedly increases appetite via GHSR-1a activation in hypothalamus and pituitary203096, Melanotan II is a cyclic heptapeptide melanocortin analog (Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2) that acts as a non-selective, high-potency agonist at MC1R, MC3R, MC4R, and MC5R, influencing pigmentation, appetite, and sexual behavior3545.