Alpha-melanocyte-stimulating hormone (α-MSH)

**Alpha-melanocyte-stimulating hormone** (**α-MSH**) is an endogenous tridecapeptide hormone derived from proopiomelanocortin cleavage. It belongs to the melanocortin family and acts primarily by binding to several subtypes of melanocortin receptors—most notably MC1R on skin/hair cells for pigmentation effects but also centrally acting on MC3R/MC4R to regulate appetite and energy balance. In addition to its role in stimulating melanin production after UV exposure—which helps protect against DNA damage—it exerts anti-inflammatory effects across various tissues by modulating cytokine expression. In clinical medicine its synthetic analogs are used for rare photodermatoses like erythropoietic protoporphyria as well as hypoactive sexual desire disorder; investigational uses include obesity treatment via central appetite pathways. While not itself a direct therapeutic target like a receptor or enzyme—rather serving as an endogenous ligand—its downstream signaling axis is targeted pharmacologically through agonist analogs with improved potency/selectivity profiles compared to native peptide. The biological roles extend beyond pigmentation into metabolism regulation, inflammation control/protection from tissue injury after ischemia-reperfusion events—and possibly influence psychiatric disease risk via neuroendocrine circuits. The term "Alpha-melanocyte-stimulating hormone" refers specifically to the peptide ligand—not its primary pharmacological targets which are the various **melanocortin receptors**.[1][2][3] **Note:** There is something incorrect about using "Alpha-melanocyte-stimulating hormone" as a *therapeutic target* per se—it is not itself considered a classic druggable target like a receptor/enzyme/transporter but rather an endogenous ligand whose pathway can be modulated therapeutically by mimetic drugs.[1]

Other names

Alpha-MSHα-MSHAlpha-melanotropinMelanotropin alpha

Drugs acting on this pathway are typically **agonists** at melanocortin receptors, especially MC1R, MC3R, MC4R, and sometimes MC5R. Their effects include stimulation of melanin synthesis in melanocytes, suppression of appetite via hypothalamic pathways, modulation of sexual function through central nervous system mechanisms, and anti-inflammatory/cytoprotective actions[1][2][9].