Effects of mu and kappa opioid receptor agonists and antagonists on contraction of isolated colon strips of rats with cathartic colon

AIM:To study the effects of mu and kappa opioid receptoragonists and antagonists on the isolated colon strips of ratswith cathartic colon.METHODS:Cathartic colon model was established byfeeding rats with contact laxatives,and effects of mu andkappaopioid receptor agonists and antagonists on electricity-stimulated contraction of isolated colon strips of rats withcathartic colon were observed.RESULTS:Compared with control group,exogenous muandkappa agonists inhibited significantly electricity-stimulatedcontraction of strips of cathartic colon (8.50±0.89 mm,6.24±0.91 mm,3.35±0.6 mm vs 11.40±0.21 mm P<0.01;8.98±0.69 mm,6.89±0.71 mm,4.43±0.99 mm vs 11.40±0.21mm,P<0.01).In contrast,the exogenous mu antagonistsignificantly enhanced electricity-stimulated contraction ofisolated colon strips (13.18±0.93 mm,15.87±0.98 mm,19.46±1.79 mm vs 11.40±0.21 mm,P<0.01),but kappaantagonist had no effect on the isolated colon strips of ratswith cathartic colon.CONCLUSION:Mu and kappa opioid receptors are involvedin the regulation of colon motility of rats with cathartic colon.