AlphaMSH

Alpha-melanocyte-stimulating hormone (alpha-MSH) is a peptide hormone in the melanocortin family derived from the pro-opiomelanocortin (POMC) precursor. In humans, alpha-MSH is produced by pituitary cells and by various peripheral tissues, including skin and immune cells, through post-translational processing of POMC.

Alpha-MSH acts by binding to melanocortin receptors, notably MC1R, MC3R, MC4R, and to a lesser extent MC5R. Activation of MC1R in melanocytes stimulates eumelanin production, contributing to pigmentation. Signaling through MC4R (and to a lesser extent MC3R) in the central nervous system influences energy balance and appetite. Through these receptors, alpha-MSH also exerts anti-inflammatory and immunomodulatory effects, and it can modulate neural activity.

Physiologically, alpha-MSH participates in pigmentation, regulation of inflammation and immune responses, appetite and energy homeostasis, and neuroprotection in experimental models. Its anti-inflammatory actions are mediated by suppression of pro-inflammatory cytokines and modulation of immune cell activity, often involving melanocortin receptor pathways.

Therapeutically, alpha-MSH and synthetic analogs have been investigated for inflammatory and autoimmune conditions, obesity, and neurodegenerative diseases. A long-acting analog, afamelanotide, has been developed for photoprotection in conditions such as erythropoietic protoporphyria, illustrating the clinical potential of melanocortin agonists. Clinical applications depend on receptor selectivity, pharmacokinetic properties, and tissue targeting, and research continues to clarify optimal uses and safety profiles.

See also: Melanocortin receptors; Pro-opiomelanocortin; Afamelanotide.