Opiate-like peptides in the bovine adrenal medulla : immunohistochemical localization and radioimunological detection

Abstract

Immunohistochemical and radioinmunological methods are used to examine the distribution, localization and secretion of endogenous opiate peptides in the bovine adrenal medulla and isolated bovine adrenal chromaffin cells. The following observations were made: 1° Leucine-enkephalin and methionine-enkephalin were localized in bovine adrenal gland cryostat sections with the aid of immunofluorescent techniques. Their immunoreactivity was identical. 2° The enkephalin-like immunoreactivity was found only in gland cells identified as being adrenaline-synthesizing. 3° A highly specifie and highly sensitive antisera directed against synthetic dynorphin-(1-13) was produced by a new method which does not require conjugation of the peptide to a protective molecule. 4° This antiserum was the basis of a dynorphin radioimmunoassay which enabled the detection of dynorphin immunoreactive material in bovine adrenal medulla extracts and isolated bovine adrenal chromaffin cell extracts, 5° Immunoreactive-dynorphin was found to be concentrated mainly in the chromaffin cells and in quantifies of the same order as leucine enkephalin. 6° Nicotinic stimulation (acetylcholine or nicotine) or cell depolarization (KC1) were found to induce a significant release of immunoreactivedynorphin over basai release. 7° The ratio of immunoreactive-leucine-enkephalin te immunoreactive-dynorphin release was found to be equivalent to the ratio of immunoreactive-leucine-enkephalin to immunoreactive-dynorphin content in the chromaffin cells. This data suggests that in the bovine adrenal medulla: 1) methionine and leucine-enkephalin are co-stored together in adrenaline-synthesizing cells; 2) dynorphin exista in and is secreted from bovine adrenal chromaffin cells; 3) dynorphin may have a role of equal importance to the enkephalins since it is found in equivalent quantities in the isolated chromaffin cells.