Effects of Morphine on Interstitial Cells of Cajal in Rabbit Colon and Small Intestinal Transit: An Experimental Study

Objective: This study aims to investigate the effect of morphine with naloxone on intestinal peristalsis and the number of interstitial cells of Cajal (ICC) in colon tissues of rabbits. Methods: Thirty rabbits were randomly divided into five groups (n=6, each group): saline control group (NS group), low concentration of morphine group (L group), medium concentration of morphine group (M group), high concentration of morphine group (H group), medium concentration of morphine and naloxone mixed with antagonist group (NM group). Rabbits in these five groups were administered with an epidural puncture tube and dorsal epidural analgesia pump, and were continuously infused for seven days. Fecal characteristics were observed, and the ink propulsion rate was calculated. The expression level of ICC C-kit protein in colon tissues was tested by western blot. Results: The stool characteristics in the L, M and H groups were more severe than those in the NS and NM groups. Furthermore, the intestinal propulsion rate in the L, M and H groups was lower than that in the NS and NM groups. The C-kit mRNA and protein expression in the colon of rabbits were significantly lower in the L, M and H groups, when compared to the NS and NM groups. Conclusion: Naloxone blocked the mRNA and protein expression of C-kit, and improved intestinal motor function.