MSH (melanocyte-stimulating hormone), produced by the pituitary gland, regulates the pigmentation of the skin by increasing melanin production in melanocytes. Alpha-MSH corresponds to aa 138-150 of corticotropin precursor (pro-opiomelanocortin, POMC). Alpha-MSH is an endogenous melanocortin receptor agonist (Ki values are 0.12, 31, 660 and 5700 nM for MC1, MC3, MC4 and MC5 receptors respectively). Alpha-MSH is an anti-inflammatory peptide which antagonizes proinflammatory mediators, including TNF-alpha, IL-6 and NO, and induces anti-inflammatory cytokine IL-10. It also inhibits food intake and induces penole erections following i.c.v. administration.