AJP - Gastrointestinal and Liver Physiology, Vol 244, Issue 1 65-G70, Copyright © 1983 by American Physiological Society
Interaction of enkephalin and caerulein on guinea pig small intestine
W. M. Yau, P. F. Lingle and M. L. Youther
This is a report on the effect of caerulein and methionine-enkephalin
interaction on mechanical contraction and acetylcholine release in vitro.
The ability of enkephalin to relax caerulein-induced contractions and the
manner in which the caerulein dose-response curve was shifted in the
presence of enkephalin strongly suggest that enkephalin and caerulein are
functional antagonists in this system. The failure of enkephalin to alter
the action of exogenous acetylcholine implies that such an antagonism is
not mediated through a competition with postsynaptic muscarinic receptors
on the muscle. Data from acetylcholine-release studies indicate that
caerulein stimulation was dose related. As with the mechanical
contractions, the release of acetylcholine in response to caerulein was
inhibited by enkephalin. However, naloxone was capable of blocking this
inhibition and restoring the release to its control level without
interfering with caerulein stimulation. These data provide evidence for the
modulatory roles of neuronal peptides in the cholinergic control of gut
motility.
