Role of endogenous 5-hydroxytryptamine in the regulation of gastric
contractions by motilin in dogs.
Haga, Norihiro, Akiyoshi Mizumoto, Minoru Satoh, Erito Mochiki, Fumie
Mizusawa, Kihachi Ohshima, and Zen Itoh.
Gastrointestinal Research Laboratories, Institute for Molecular and
Cellular Regulation, and Health Service Center, Gunma University,
Maebashi, Japan
APStracts 2:0150G, 1995.
It has been suggested that 5-hydroxytryptamine 3 (5-HT3) receptors are
involved in the control of phase III contractions in the stomach. We
examined the effect of depletion of endogenous 5-HT by para
-chlorophenylalanine (pCPA) on spontaneously and motilin-induced phase
III contractions in conscious dogs, and the effect of 5,6
-dihydroxytryptamine (5,6-DHT) in an isolated perfused dog stomach.
Three-day treatment with pCPA significantly reduced plasma 5-HT
concentration and 5-HT content in the stomach, and strongly
suppressed the spontaneous and motilin-induced phase III contractions
in the stomach. When spontaneous phase III contractions recovered in
the stomach after 3-day treatment, exogenous motilin induced typical
phase III-like contractions, and the 5-HT content in the muscle layer
was recovered to the normal pretreatment level. In the perfused
stomach, 5,6-DHT decreased 5-HT content in the muscle layer alone,
and abolished motilin-induced contractions. In conclusion, endogenous
5-HT, probably in 5-HT-neurons, plays an important role in the
control of interdigestive phase III activity by motilin in the
stomach.
Received 27 December 1994; accepted in final form 12 July 1995.
APS Manuscript Number G504-4.
Article publication pending Am. J. Physiol. (Gastrointest. Liver
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 30 July 1995.