Regulation of motilin release:studies with ex vivo perfused canine
jejunum.
P, Poitras, Trudel L, Miller P, Gu C. M.
Centre de recherche clinique Andr[acute]e-Viallet,
H[circumflex]opital Saint-Luc, Universit[acute]e de Montr[acute]eal,
Montreal, Canada
APStracts 3:0139G, 1996.
The regulatory process of motilin release was studied in segments of
canine jejunum isolated and perfused ex vivo. The secretion of
motilin in the effluent venous system of the isolated intestine was
measured by radioimmunoassay in response to various pharmacological
agents injected intra-arterially. Muscarinic agonist and antagonist
respectively increased and decreased the release of motilin. The
stimulatory effect of carbachol was still documented after
tetrodotoxin 10-5 M was injected in the system to block neural
influence on M cells. Bombesin and morphine also increased the
release of motilin. The effect of bombesin was still documented in
presence of atropine or tetrodotoxin, but the stimulatory morphine
effect was blocked by atropine. Phenylephrine and octreotide both
decreased the release of motilin stimulated by carbachol in a jejunal
segment pretreated and denervated with tetrodotoxin. Therefore, a
revised model for the regulation of motilin release from M cells of
intestinal mucosa can now be proposed: cholinergic and bombesin
receptors are present on M cells to encode a stimulatory signal,
while adrenergic and somatostatin receptors are responsible for
inhibitory transmission. The stimulatory effect of morphine is
mediated via a muscarinic transmitter.
Received 20 October 1995; accepted in final form 8 July 1996.
APS Manuscript Number G460-5.
Article publication pending Am. J. Physiol. (Gastrointest. Liver
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 25 July 1996