Regional heterogeneity in the ratio of alpha-MSH: beta-endorphin in rat brain.
The molar ratio of alpha-MSH: beta-endorphin varies markedly among discrete microdissected regions of rat brain ranging from 0.57 in the median eminence to 2.74 in the lateral septum. This finding demonstrates that alpha-MSH and beta-endorphin (beta-END) are not uniformly distributed in a 1:1 molar ratio in rat brain as one might predict based on the consideration that the two peptides are synthesized in equimolar amounts as part of a common precursor molecule, pro-opiomelanocortin. The data indicate instead that the concentrations of alpha-MSH and beta-END, the two predominant peptides expressed by opiomelantropinergic neurons, are independently regulated in rat brain. The heterogeneity of alpha-MSH: beta-END ratios suggests that the regulation of alpha-MSH and beta-END is regionally specific and may impart functional selectivity to the multisecretory opiomelanotropinergic neuronal system.
D000818:Animals; D001923:Brain Chemistry; D003429:Cross Reactions; D004723:Endorphins / Q000032:analysis*; D008297:Male; D009074:Melanocyte-Stimulating Hormones / Q000032:analysis*; D011863:Radioimmunoassay / Q000379:methods; D051381:Rats; D011919:Rats, Inbred Strains; D014018:Tissue Distribution; D001615:beta-Endorphin
D004723:Endorphins; D001615:beta-Endorphin; D009074:Melanocyte-Stimulating Hormones