Interaction between CCK and opioids in the modulation of the recto
-colonic inhibitory reflex in rats.
Gu[acute]e, Mich[grave]ele, Chantal Del Rio, Jean Louis Junien, and
Lionel Bu[acute]eno.
Department of Pharmacology, INRA, BP 3, 31931 TOULOUSE cedex,
FRANCE; Institut de Recherche JOUVEINAL, BP 100, 94265 FRESNES cedex,
FRANCE
APStracts 2:0054G, 1995.
The effects of CCK-8s as well as the involvement of opioid system,
were evaluated in the rectal distension (RD)-induced colonic motor
inhibition in rats. Rats were surgically prepared with electrodes
implanted on the proximal colon and a catheter was implanted in
lateral ventricle of the brain. Rectal distention was performed by
inflation (0.0 - 1.6 ml) of a balloon rectally inserted. RD with 1.6
ml, induced an inhibition of the colonic spike bursts (3.1 +/- 0.5
per 5 min vs 8.1 +/- 0.4 before RD). Intracerebroventricular but not
intravenous injection of CCK-8s and A-71623 (50 and 100 ng/kg)
reduced the RD-induced colonic motor inhbition, while A-63387 was
ineffective. PD 135, 158 (10 [mu]g/kg ICV) suppressed the inhibitory
reflex caused by RD. Devazepide (100 [mu]g/kg ICV) had no effect in
this reflex function. Devazepide (1 [mu]g/kg), naloxone (0.1 mg/kg)
and nor-BNI (10 mg/kg) reversed the blocking effect of CCK-8s, while
PD 135,158 (0.1 [mu]g/kg) and naltrindole (1 mg/kg) have no effect.
In conclusion, CCK-8s acts on central CCK-A receptors to modulate the
RD-induced inhibition of colonic motility through pathway involving
activation of endogenous k receptors.
Received 26 July 1994; accepted in final form 7 March 1995.
APS Manuscript Number G279-4.
Article publication pending Am. J. Physiol. (Gastrointest. Liver
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 4 April 1995.