Effect of epidural morphine for analgesia on the number of interstitial cells of Cajal in rabbit colon / 中华麻醉学杂志

ABSTRACT

Objective To investigate the effect of epidural morphine for analgesia on the number of interstitial cells of Cajal (ICC) in the rabbit colon.Methods Thirty healthy rabbits of either sex,weighing 2.0-2.5 kg,were randomly divided into 2 groups (n =15 each)control group (group C) and morphine group (group M).The animals were anesthetized with iv 20% urethane 4 ml/kg.The epidural analgesia was performed at L3,4 interspace.In group M morphine 9.2 ug· kg-1 · h-1 was infused into the epidural space for 7 consecutive days,while the equal volume of normal saline was infused instead in group C.The characteristics of excrement and constipation were recorded during morphine infusion.Normal saline or Chinese ink mixture 5 ml was administered via a gastric tube inserted through the mouth 1 day after the end of administration.The rabbits were sacrificed 30 min later and laparotomy was performed.The intestinal segment numbered from the pylorus to the ileocecal region of the bowel was removed and the length of the intestinal segment and propelled distance of the ink within the intestinal tract were measured in the tension-free state.The rate of propelled distance was calculated.The proximal and distal colon tissues were taken for measurement of the expression of c-kit (by immunohistochemisty) and ICC count,and stained with haematoxylin and eosin for examination of pathological changes.Results Compared with group C,the incidence of constipation was significantly increased,and the rate of propelled distance,and expression of c-kit and ICC count in proximal colon tissues were decreased at 3-7 days of morphine infusion (P ＜ 0.05),and no significant change was found in the expression of c-kit and ICC count in distal colon tissues in group M (P ＞ 0.05).Conclusion Epidural morphine for analgesia can inhibit the motor function of the intestinal tract in rabbits,and reduction in the number of ICC count in proximal colon is involved in the mechanism.