Objective: To investigate the influence of Changyanqing oral liquid on intestinal mucosal permeability of ulcerative colitis mice and to explore its possible mechanism. Method: The ulcerative colitis (UC) model in BALB/c mice was induced by trinitrobenzene sulfonic acid (TNBS). The UC model mice were randomly divided into normal control group

model control group

salicylazosul fapyridine (SASP) group (0.5 g· kg-1)

Changyanqing low-

moderate- and high-dose group(0.176

0.352

0.528 g· kg-1). The plasma diamine oxidase (DAO) activity was detected using ELISA method. The occludin

claudin

zonula occludens(ZO-1) gene expression and protein expression of colon parts were detected using RT-qPCR and Western blot method. Result: The DAO activity in Changyanqing oral liquid of all dosage groups was significantly lower than that in model group with significant difference (P <0.05). The expression levels of occludin

claudin 1

ZO-1 mRNA in Changyanqing of all dosage groups were higher those in model group with significant difference (P<0.05). Better concentration-response relationship was shown between the level claudin 1

ZO-1

occludin mRNA expression and drug delivery dosage. The expression level of ZO-1 and occludin proteins in the intestine of all Changyanqing dosage groups were higher than that those in model group with significant difference (P<0.05). Conclusion: The mechanism of Changyanqing oral liquid in treating ulcerative colitis may be achieved by improving the intestinal mucosal permeability

which is relevant to regulating the expression level of occludin

claudin and ZO-1.