Function
While Hexarelin is investigated for effects on GH secretion, cardiac protection, and muscle metabolism, with higher GH secretory potency than earlier GHRPs1929, 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 Hexarelin works as a potent synthetic hexapeptide (examorelin) that agonizes GHSR-1a to stimulate GH release and also binds CD36, influencing cardiovascular and metabolic pathways19212996, 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.