Specific radioimmunoassay of human beta-endorphin in unextracted plasma.
With an antiserum against human beta-endorphin (beta-EP) crossreacting less than 2% with human beta-lipotropin (beta-LPH) by weight we have developed a radioimmunoassay that can detect 1 pg beta-EP in diluted raw plasma. In a.m. fasting plasma of 14 normal subjects beta-EP ranged from less than 5 to 45 pg/ml. beta-EP was elevated in untreated, but normal in successfully treated Cushing's disease; undetectable in a patient with adrenal adenoma; extremely high in Nelson's syndrome; and elevated in a patient with bronchogenic carcinoma before, but undetectable after tumor resection. In subjects with intact hypothalamic-pituitary-adrenal axis, beta-EP was undetectable after dexamethasone and increased after metyrapone administration and insulin-induced hypoglycemia. beta-EP concentration was considerably lower in serum than in simultaneously collected plasma, but increased in serum left unfrozen for several hours after clot removal. Thus, beta-EP behaves like a hormone responding to the same stimuli as ACTH and beta-LPH and blood appears to contain enzymes both generating and destroying immunoreactive beta-EP.
D000236:Adenoma / Q000097:blood; D000310:Adrenal Gland Neoplasms / Q000097:blood; D002283:Carcinoma, Bronchogenic / Q000097:blood; D003480:Cushing Syndrome / Q000097:blood; D003907:Dexamethasone / Q000494:pharmacology; D004723:Endorphins / Q000097:blood*; D006801:Humans; D008175:Lung Neoplasms / Q000097:blood; D008797:Metyrapone / Q000494:pharmacology; D009347:Nelson Syndrome / Q000097:blood; D011863:Radioimmunoassay
D004723:Endorphins; D003907:Dexamethasone; D008797:Metyrapone