Objective: To observe the prevention effect of Huangqin Tang (HQT) on iriontecan (CPT-11) induced delayed diarrhea in mice. Method: Forty healthy male ICR mice were randomly divided into 5 groups

a model of delayed-onset diarrhea was set up by intraperitoneal injection CPT-11 continuously to establish a model group

control group was given saline instead of irinotecan. Low dosage group (5 g·kg-1)

medium dosage group (10 g·kg-1) and high dosage group(20 g·kg-1)of Huangqin Tang were ig administration respectively

once a day for 8 days before one day of ip. The occurrence of delayed diarrhea and the change of body weight were observed;the mice were killed on day 9th

the samples of blood; colon; cecum; jejunum and ileum were collected.The level of mucositis was observed by using light microscope based on Chiu criteria; nitrogen oxide(NO) levels in intestinal tissue homogenate were detected by classic Griess method. The expressions of proliferating cell nuclear antigen(PCNA) were detected by immunohistochemistry. Numbers of neutrophils were determined by Giemsa staining. Result: Injection of CPT-11 could cause significantly delayed diarrhea. The degree of diarrhea incidence from medium and high dosage groups of HQT was significantly lower compared with the diarrhea model group (P<0.05)

and the degree of weight loss also got the same result. The degree of intestinal bowel damages resulted from group of cecum; colon's medium and high group of HQT were significantly lower than the diarrhea model group(P<0.05)

which showed a certain dose-effect relationship with the dosage. The level of NO expression in colon homogenates was promoted and the PCNA expression in colon mucosa was decreased(P<0.05)

the number of neutrophils also got increased (P<0.01). Conclusion: The pre-application HQT can prevent the occurrence of delayed diarrhea CPT-11 by improving the degree of intestinal mucosa

promoting the level of NO expression

decreasing PCNA expression

it can also alleviate neutropenia syndrome.