CONCOMITANT SECRETION OF γ-MSH WITH ACTH AND β-ENDORPHIN IN HUMANS

Publisher Website
Google Scholar
Abstract
Using a specific radioimmunoassay for γ-melanotropin (γ-MSH), one of the predicted fragments in the amino-terminal portion of the adrenocorticotropin(ACTH)-(β-lipotropin (β-LPH) precursor, γ-MSH-like immunoreactivity γ-MSH-LI) was detected in human plasma from 4 of 5 patients with Addison's disease and 2 of 3 patients with Nelson's syndrome. None of the normal subjects or patients with Cushing's disease showed detectable concentrations (more than 150 pg/ml) of γ-MSH-LI. γ-MSH-LI was secreted concomitantly with ACTH-like immunoreactivity (ACTH-LI) and β-endorphin-like immunoreactivity (β-endorphin-LI) in response to insulin-induced hypoglycemia and the administration of lysine-vasopressin. Conversely, intravenous injection of cortisol lowered plasma concentrations of γ-MSH-LI concomitantly with those of ACTH-LI and β-endorphin-LI. Gel chromatographic studies of the plasma extracts showed a single peak of γ-MSH-LI near the elution position of human β-LPH. These results suggest that γ-MSH-LI in human plasma is present as a big form and that this big γ-MSH is secreted concomitantly with ACTH and β-endorphin.