α-Melanocyte stimulating hormone (α-MSH) is a pituitary hormone that plays a key role in appetite control and the skins UV protection and development of pigmentation. Also has effects on energy homeostasis, sexual activity, and as an anti-inflammatory. Potent agonist of the melanocortin receptors MC1, MC3, MC4, and MC5 (Ki=0.12, 31, 660, and 5700nM, respectively), but not MC2.