β-Endorphin in pituitary intraglandular colloid of intermediate lobe origin

Radioimmunoassay (RIA) detected the presence of beta-endorphin in the intraglandular colloid (IGC) of bovine pituitary intermediate lobe origin. The amount of beta-endorphin recovered in each of twelve samples ranged from 0.15 to 218.30 pmol/mg protein. A second group of assays [amino acid analysis, high performance liquid chromatography (HPLC) and mass spectral analysis] confirmed the RIA findings in another series of colloid samples. Approximately 75 pmol was collected from eight pooled glands. beta-Endorphin is an addition to the list of peptide hormones (e.g., methionine-enkephalin, adrenocorticotropin, arginine-vasopressin, alpha-melanocyte-stimulating hormone, beta-lipotropin and somatostatin) previously discovered in IGC by this laboratory.