OBJECTIVETo investigate the influence of Weichang Anwan on the treatment of IBS-D in model rats.

METHODAnimal model of compound diarrhea was induced by a lactose enriched diet in the Wistar rat, combining with restraint stress. At first, the best cycle of taking medicine was tested. In order to decide the best cycle of taking medicine, 24 female Wistar rats were randomly divided into normal control group, model group and 60 mg x kg(1) x d(-1) weichangan group. The rate of weight increase, the rate of diarrhea, the incubation period of diarrhea and the diarrhea index were observed. And then 45 female Wistar rats randomly divided into five groups: normal control group, model group and Weichang Anwan groups of high, medium and low doses( 80, 60, 40 mg x kg(-1) x d(-1)). The mast cells in mucous membrane were observed by light microscope. The level of NO in blood serum was checked by the method of nitrate reductase. 5-HT in blood serum was detected by fluorimetry. The level of SP in colon was measured by radioimmunoassay.

RESULTAfter taking Weichang Anwan for 4 days, the rate of weight increase in Weichangan group was higher than the model group's. And the rate of diarrhea was lower significantly. So the best cycle of taking medicine was 4 days. The levels of NO and 5-HT in blood serum decreased remarkably in the model group than those of the normal control group. At the same time, the amount of the mast cells and the level of SP in colon significantly increased. Compared with the model group, the levels of NO and 5-HT in blood serum increased remarkably in the groups of high doses and medium doses. Meanwhile, the amount of the mast cells and the level of SP in colon decreased significantly.

CONCLUSIONWeichang Anwan has the effect of antidiarrhea. It can adjust the levels of NO and 5-HT in blood serum and can inhibit the expression of SP in colon which can active the mast cell. Weichangan can also decrease the amount of the mast cells directly.