Journal of Neuroscience, Vol 2, 1150-1156, Copyright © 1982 by Society for Neuroscience
Proportional secretion of opioid peptides and catecholamines from adrenal chromaffin cells in culture
SP Wilson, KJ Chang and OH Viveros
Bovine adrenal medullary chromaffin cells were used to study the
relationship between opioid peptide and catecholamine secretion from the
adrenal medulla. Stimulation of chromaffin cells by acetylcholine,
nicotine, veratridine, barium, or Ionomycin produced secretion of opioid
peptides and catecholamines which was proportional to the cellular content
of these substances. Nicotine-evoked secretion of opioid peptides and
catecholamines was dependent on extracellular calcium and was blocked by
d-tubocurarine. Increased cellular content of opioid peptides and decreased
catecholamine content induced by treatment of chromaffin cells with
reserpine or tetrabenazine were reflected in the secretion of
proportionally larger amounts of opioid peptides and smaller amounts of
catecholamines when compared with secretion of these substances from
untreated cells. Peptides of up to 25,000 daltons that express opiate
activity only following digestion with enzymes, such s trypsin and
carboxypeptidase B, also are secreted from chromaffin cells in the same
proportion of their cellular content as are catecholamines and opioid
peptides. Opioid peptides were secreted in proportion to total
catecholamines but not in proportion to either epinephrine or
norepinephrine alone, suggesting that the peptides are secreted from both
epinephrine- and norepinephrine- containing cells in the cultures. The
results are consistent with the co-storage of opioid peptides and opiate
receptor-inactive peptides containing enkephalin sequences in chromaffin
vesicles and with the all- or-none exocytotic secretion of chromaffin
vesicles content in response to stimulation of the adrenal medulla.