Objective To explore the possible mechanism of Mazhi Jiangzhuo Fang in the treatment of irritable bowel syndrome（ IBS-C）. Methods 60 Wistar rats were randomly divided into normal group（ n = 10） and modeling group（ n = 50）. Rat models of IBS-C were established with ice water gavage method in modeling group. 48 completed modeled rats were randomly divided into model group（ n = 9）

positive drug control group（ n = 10）

high dose group（ n = 10）

middle dose group（ n = 10） and low dose group（ n = 9）. Positive drug control group was given Cisapride tablets（ 3. 6 mg /（ kg ·d）） by gavage. High

middle and low dose groups were given Mazhi Jiangzhuo Fang granules 25. 2 g /（ kg·d）

12. 6 g /（ kg·d） and 6. 3 g /（ kg·d） by gavage

respectively. Model group was given equivalent distilled water by gavage. Normal group was fed normally. After 14 days

the pathological changes of intestinal tissue was observed by hematoxylin and eosin stain（ HE stain）. Changes in amount and shape of interstitial cell of Cajal（ ICC） were detected. The positively expressed proportion of c-kit gene and integral optical density（ IOD） was analyzed with image analysis system of Image-Pro Plus 6. 0. Results The protuberances of ICC in model group rats were shorten. Banding and reticulation structure were not obvious. The amount

shape

distribution and reticulated connection of rats’ ICC in medication administration groups were similar to those in normal group. The positively expressed proportion of c-kit gene and IOD in model group were less than those in normal group（ P <0. 05）. The positively expressed proportion of c-kit gene and IOD in high and middle dose groups and positive drug control group were more than those in model group（ P < 0. 05）

especially in high and middle dose groups（ P <0. 05）. Conclusion Mazhi Jiangzhuo Fang may improve IBS-C by increasing the amount of ICC

improving the shape and structure of ICC

and strengthening the rhythmic contraction of intestinal tract.