Preproenkephalin B-derived opioid peptides in human phaeochromocytomas
Yanase, T.; Nawata, H.; Kato, K.; Ibayashi, H.
Acta Endocrinologica 114(3): 446-451
1987
ISSN/ISBN: 0001-5598 PMID: 2882641 Document Number: 289171
We demonstrated the presence and the secretion in vivo and in vitro of immunoreactive preproenkephalin B-derived opioid peptides (.alpha.-neoendorphin, dynorphin and leumorphin) in human phaeochromocytomas. In seventeen human phaeochromocytomas and two human adrenal medullas, the tissue contents of immunoreactive preproenkephalin B-derived opioid peptides (.alpha.-neoendorphin, dynorphin and leumorphin) and leu-enkephalin were studied by specific RIAs. Compared with a remarkable wide distribution in amounts of immunoreactive leu-enkephalin (1063 .+-. 437 .mu.g/ml, mean .+-. SE), small amounts of immunoreactive .alpha.-neoendorphin (22.6 .+-. 6.4 pg/mg) and dynorphin (8.5 .+-. 1.2 pg/mg) were detected in all seventeen human phaeochromocytomas and the two human adrenal medullas. Leumorphin-like immunoreactivity was detected in only four tumors. Gel chromatographic studies revealed the presence of preproenkephalin B-derived peptides and their high molecular forms. A significant positive correlation between the tumor tissue contents of immunoreactive .alpha.-neoendorphin and of dynorphin was observed. Nicotine (10-5, 10-4 mol/l) significantly stimulated the secretion of immunoreactive .alpha.-neoendorphin and dynorphin as well as leu-enkephalin and catecholamines from cultured human phaeochromocytoma cells. Administration of 1 mg of glucagon to a patient with medullary phaeochromocytoma induced a rapid increase in the plasma concentration of immunoreactive .alpha.-neoendorphin with a concomitant increase in plasma catecholamines. These results indicate the presence of preproenkephalin B-derived opioid peptides in human phaeochromocytomas and human adrenal medullas and their secretion in human phaeochromocytomas.