B Hormone; Chromatophore Hormone; Intermedin; Intermedina; Melanotropin; MSH; Pigment Hormone.
CAS — 9002-79-3.
Melanocyte-stimulating hormone is a polypeptide isolated from the pars intermedia of the pituitary of fish and amphibia which causes dispersal of melanin granules in the skin of fish and amphibia and allows adaptation to the environment. In adult humans, the pituitary gland lacks a distinct intermediate lobe, and the pituitary is not thought to secrete melanocyte-stimulating hormone (MSH) directly. However, the precursor molecule, pro-opiomelanocortin, is cleaved in the pituitary into corticotropin, the glycoprotein β-lipotrophin (β-LPH), and an amino-terminal peptide. Subsequent processing in other tissues, such as the brain and gastrointestinal tract, may yield three forms of MSH, α-MSH (via corticotropin cleavage), β-MSH, and γ-MSH. The presence and function of these melanocytestimulating hormones in man are uncertain. A receptor analogous to that in amphibians is apparently lacking in humans; effects on skin pigmentation emanating from the pituitary are primarily mediated by corticotropin. Release of melanocyte-stimulating hormone is inhibited in animals by melanostatin; there is also evidence for a hypothalamic releasing factor (MRF). Melanocyte-stimulating hormone is under investigation, as αMSH, in the prevention and treatment of ischaemic intrinsic acute renal failure. A synthetic analogue of α-MSH (4-L-norleucine-7D-phenylalanine-α-MSH; melanotan-I) is under investigation as a stimulant of melatonin production for the prevention of sunburn.
Published May 08, 2019.