ヒト下垂体、異所性ACTH産生腫瘍および血漿中に存在するβ-endorphin活性のsize heterogeneityに関する研究

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Among the various fragments of β-lipotropin (β-LPH), β-endorphin (β-EP) is found to be the most potent morphinomimetic peptide by bioassay and opiate receptor binding assay. A very' sensitive radioimmunoassay (RIA) for β-EP has been developed with an antiserum obtained in a rabbit immunized with β-EP contained in crude porcine ACTH preparations (Organon). Using this RIA for β-EP we have investigated the size-heterogeneity of β-EP immunoreactivity in a human pituitary, ectopic ACTH-producing tumors and normal and Addisonian plasma extracts by Sephadex gel chromatography and sodium dodecyl sulfate polyacrylamide gel electrophoresis. In the human pituitary and ectopic ACTH-producing tumors extracts we have observed the presence of "big-big"-β-EP ("big"-β-LPH) which was considered to be a common precursor to ACTH and β-LPH/β-EP proposed by Mains et al., in addition to β-LPH and β-EP. β-EP has been identified also in the normal human plasma extracts by Sephadex gel chromatography and RIA for β-EP. Following metyrapone and insulin stimulation tests plasma concentrations of β-EP were significantly increased in normal subjects. Extremeiy high plasma concentrations of β-EP were demonstrated in patients with Addison's disease. These data suggest that the human pituitary and ectopic ACTH-producing tumors synthesize β-LPH/β-EP as well as ACTH via the production of a common precursor.
神戸大学の論文