Abstract: Objective Radiation enteritis is a significant clinical problem in patients receiving ionizing radiation directed to the abdomen or pelvis.The aim of this study was to uncover the role of compound matrine in acute actinic enteritis prevention and to provide the experiment evidence for compound Matrine injection in clinical treatment of acute radiation enteritis. MethodsForty-two male Sprague-Dawley rats were used in the study.The rats were randomly divided into four groups.GroupⅠ(n=6):normal rats and isotonic saline without abdominal irradiation(sham control group); Group Ⅱ(n=12): abdominal irradiation (10 Gy) and high dose compound matrine injection (2 ml/kg) for seven days following irradiation; GroupⅢ(n=12): abdominal irradiation and low dose compound matrine injection (0.4 ml/kg) for seven days following irradiation.Group Ⅳ(n=12).abdominal irradiation (10 Gy) and isotonic saline.Eight days after irradiation, all the animals were sacrificed with lethal dose sodium thiopental.The small intestine were removed and washed with isotonic saline solution and samples of the terminal ileum were fixed in buffered formalin for histopathological examination.The terminal ileum were analyzed for morphological changes.Nitrate reductase activity assay were performed to measure the NO content in homogenate of terminal ileum. ResultsThe 8th day，all rats receiving irradiation had weight loss compared with the group Ⅰ, but the compound matrine treatment group (especially GroupⅡ)had less weight loss than Group Ⅳ.The epithelial layers of the villous were significantly reduced in rats of group Ⅳ (51±8) compared to that in GroupⅡ（74±10） and groupⅢ（67±4）.Further more, the mean villous height were significantly reduced in rats of group Ⅳ(196.24±27.64) μm compared to that in GroupⅡ（283.8±47.17） μm and groupⅢ(260.3±38.59)μm.There was significant difference in intestinal NO concentration between group Ⅳ and the other groups（P＜0.001). Conclusion The compound matrine could relief the gastrointestinal tract reaction and reduce the pathomorphological changes of intestine in acute radiation enteritis rats, as well as repair the intestinal mucosa.The compound matrine could relief the gastrointestinal tract reaction.Its potential mechanism may be compound. Matrine can reduce the intestinal NO concentration.