Distribution, subcellular localization and identity of immunoreactive alpha-melanotropin in the pituitary gland and brain.
In homogenates of adult human or rat hypothalamic tissue, immunoreactive alpha-MSH (alpha-MSHi) is concentrated in synaptosomes, suggesting that it is localized in neurons. This conclusion is supported by immunohistochemical results on the localization of alpha-MSHi in the brain. The function of alpha-MSHi in the hypothalamus is undefined but the amount of alpha-MSH in this tissue increases in young rats and decreases in old rats. There is little alpha-MSHi in pituitary glands from human abortuses before the 15th gestational week. Thereafter the amount of alpha-MSHi in the anterior and neurointermediate lobes increases appreciably. When acetic acid extracts of each lobe were analysed by high-pressure liquid chromatography the alpha-MSHi in extracts of the anterior lobe had a retention time equal to that of desacetyl alpha-MSH; little if any alpha-MSHi had a retention time identical to that of desacetyl alpha-MSH; alpha-MSH, if present in these extracts, appeared to be a minor component. A similar analysis of extracts of adult human hypothalamic tissue yielded results suggesting that the alpha-MSHi in this tissue is also attributable largely to desacetyl alpha-MSH.
D000328:Adult; D000375:Aging; D000818:Animals; D001923:Brain Chemistry; D005260:Female; D005333:Fetus; D006801:Humans; D007118:Immunoassay; D008297:Male; D009074:Melanocyte-Stimulating Hormones / Q000032:analysis*; D009929:Organ Size; D010902:Pituitary Gland / Q000032:analysis* / Q000254:growth & development; D011247:Pregnancy; D051381:Rats; D013347:Subcellular Fractions / Q000032:analysis; D014018:Tissue Distribution
D009074:Melanocyte-Stimulating Hormones