Effects of morphine and naloxone on feline colonic transit.
The effects of endogenous and exogenous opioid substances on feline colonic transit were evaluated using colonic transit scintigraphy. Naloxone (0.3 mg/kg, i.m.) accelerated emptying of the cecum and ascending colon, and filling of the transverse colon. Endogenous opioid peptides thus appear to play a significant role in the regulation of colonic transit. At a moderate dose of morphine (0.1 mg/kg, i.m.), cecum and ascending colon transit was accelerated, while at a larger dose (1.0 mg/kg, i.m.) morphine had no effect. Since naloxone, a relatively nonspecific opioid antagonist, and morphine, a principally mu opioid receptor agonist, both accelerate proximal colonic transit, a decelerating role for at least one of the other opioid receptors is inferred.
Krevsky
B
B
Department of Medicine, Temple University School of Medicine, Philadelphia, PA 19140.
Libster
B
B
Maurer
A H
AH
Chase
B J
BJ
Fisher
R S
RS
D000818:Animals; D002415:Cats; D002432:Cecum / Q000187:drug effects; D003106:Colon / Q000187:drug effects; D004723:Endorphins / Q000502:physiology*; D005260:Female; D005772:Gastrointestinal Transit / Q000187:drug effects*; D007205:Indium Radioisotopes; D009020:Morphine / Q000494:pharmacology*; D009270:Naloxone / Q000494:pharmacology*
D004723:Endorphins; D007205:Indium Radioisotopes; D009270:Naloxone; D009020:Morphine