The distribution of forms of adrenocorticotropin and endorphin in normal, tumorous, and autopsy human anterior pituitary tissue: Virtual absence of 13k adrenocorticotropin

To begin to define the nature of the biosynthesis and processing of ACTH and β-endorphin in the human, anterior pituitary tissue (fresh normal and adenomatous, and autopsy) was extracted in acetic acid in the presence of protease inhibitors and subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The gel slice eluates were assayed for ACTH and β-endorphin immunoactivity. Human anterior pituitary tissue contained four major size classes of ACTH and three major size classes of β-endorphin. We found that in all tissue sources examined there was a virtual absence of 13-15K ACTH, which is a major form in the rat and mouse. When comparing extracts obtained from fresh normal or adenomatous anterior pituitary tissue, we also found a drastic decrease in/Mipotropin and ftendorphin in extracts of autopsy human anterior pituitaries. These results suggest that the biosynthesis and processing of pituitary ACTH and β-endorphin in the human may be different than in the mouse, and because of apparent postmortem proteolysis of β-endorphin, human pituitary obtained at autopsy is probably not a good source of material for biochemical studies of pituitary tissue.