[Effects of Mijiandao suppository on intestinal laxation in rats and its mechanisms]

Objective: To investigate the effects of Mijian Daotong Bowel Suppository (MJDs) on the compound diphenoxylate induced constipation model of male rats and its mechanisms. Methods: Sixty SD male rats were randomly divided into blank group, model group, positive group and MJDs group. The constipation model was established by using compound diphenoxylate gavage. The rats in blank group and model group were treated with saline by enema, the rats in positive group and MJDs group were given Kaisailu and honey decoction laxative suppository by enema, respectively, once a day for 10 days. The body weight, fecal water content, gastric emptying rate (GER) and carbon ink propulsion rate (CIPR) of rats were observed during modeling and administration. The effects of MJDs on the pathological changes of colon tissue in constipation rats were investigated by hematoxylin-eosin (HE) staining. The effect of MJDs on 5-hydroxytryptamine (5-HT) in the colon of constipation rats was investigated by ELISA kit. The effects of MJDs on the expressions of aquaporins 3 (AQP3) and aquaporins 4 (AQP4) in the colon of constipation rats were detected by immunohistochemistry. Results: After 10 days of administration, compared with the blank group, the body weight, fecal water content, carbon ink propulsion rate and colon 5-HT content in the model group were decreased significantly, while the expression levels of AQP3 and AQP4 in the colon were increased significantly (P＜0.05, P＜0.01). Compared with the model group, the fecal water content and colon 5-HT content in the positive group were increased significantly, and the expressions of AQP3 and AQP4 in the colon were decreased significantly. The body weight, fecal water content and colon 5-HT content in the MJDs group were increased significantly, and the expressions of AQP3 and AQP4 was decreased significantly (P＜0.05, P＜0.01). Compared with the positive group, the fecal water content of the MJDs group was decreased significantly, and the expressions of AQP3 and AQP4 in the colon of the MJDs group was decreased significantly (P＜0.05, P＜0.01). Gastric emptying rate was not statistically significant difference between the groups. Conclusion: MJDs has good therapeutic effects on constipation, and its mechanisms may be related to up-regulating the content of 5-HT in the colon and down-regulating the expressions of AQP3 and AQP4 in the colon.