Non-Pigmentary Actions of Alpha-Melanocyte-Stimulating Hormone: Lessons from the Cutaneous Melanocortin System

The review discussed the non-pigmentary roles of alpha-melanocyte-stimulating hormone (α-MSH) in the skin, highlighting its regulatory effects on various biological processes. It was found that melanocortin receptors, particularly MC-1R, were expressed in several non-pigmentary skin cell types, while MC-5R and MC-4R were found in sebocytes, skin mast cells, and dermal papilla cells, respectively. α-MSH exhibited lipogenic activity and had immunomodulatory effects, such as regulating chemokine expression, downregulating NF-kappaB activation, and inducing interleukin-10. It also modulated collagen metabolism in dermal fibroblasts, suggesting a role in chronic inflammatory skin responses. Additionally, α-MSH had cytoprotective activity against UVB-induced apoptosis and DNA damage, contributing to tissue homeostasis and protection during inflammation.