Endogenous cck disrupts the mmc pattern via capsaicin-sensitive
vagal afferents in the rat.
Rodr[acute]iguez-Membrilla, A., and P.vergara.
DEPARTMENT OF CELL BIOLOGY, AND PHYSIOLOGY, VETERINARY FACULTY,
UNIVERSITAT AUT[grave]oNOMA DE BARCELONA, 08193 BELLATERRA, SPAIN
APStracts 3:0153G, 1996.
A meal disrupts migrating motor complexes (MMC) in the rat intestine
through stimulation of peripheral CCKB and central CCKA receptors.
The aim of this study was to determine pathways implicated in
postprandial disruption of the MMC mediated by CCK. Sprague-Dawley
rats were prepared with electrodes for electromyography in the small
intestine and ablation of vagal afferent C-fibers by capsaicin was
carried out. Endogenous release of CCK was induced by p.o.
administration of soybean trypsin inhibitor (SBTI). In control rats
SBTI disrupted MMCs and generated an irregular spiking activity which
lasted longer than 3 h. Intravenous infusion of L-365,260 (2x10-7
moles/kg) but not of L-364,718 (3x10-9 moles) restored the MMC
pattern. In capsaicin-treated rats, SBTI did not modify fasting
activity. Infusion of CCK-8 at 3x10-9 moles/kg/h disrupted the MMC,
although the response was quantitatively and qualitatively different
from SBTI. The effect was reversed by either L-364,718 or L-365,260
i.v. and the i.c.v. infusion of L-364,718. In capsaicin-treated rats,
the i.c.v. or i.v. infusion of L-364,718 inhibited CCK-8 effects.
However the i.v. infusion of L-365,260 did not revert the MMC
pattern. These results suggest that the disruption of the MMC
mediated by CCK is due to stimulation of peripheral CCKB receptors
located in vagal afferents. This initiates a reflex including
stimulation of central CCKA receptors. Exogenous CCK also stimulates
peripheral CCKA receptors not located in capsaicin-sensitive vagal
afferent fibers.
Received 7 June 1995; accepted in final form 2 August 1996.
APS Manuscript Number G245-5.
Article publication pending Am. J. Physiol. (Gastrointest. Liver
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 29 August 1996