Abstract: Objective To investigate the effect of Bletila striata polysaccharide(BSP) on ulcerative colitis (UC) mice induced by dextran sodium sulfate (DSS) and its effect on tight junction occludin protein in intestinal mucosa. Methods Mice were randomly divided into control group, DSS model group (freely drinking 2.5% DSS solution for 7 days), salazosulfopyridine(300 mg/kg) positive control group, BSP low-dose (125 mg/kg) and high-dose groups (250 mg/kg). From the beginning of modeling, mice were given intragastric administration once a day for consecutive 7 days. The change of body weight, disease activity index (DAI) score, histopathology score and colon length were recorded to evaluate the inflammatory reaction. Expression of occludin protein in mice colon tissue was detected by Western blot. Results Compared with control group, the body weight of the model group mice was significantly reduced, the colon was shortened, the DAI and histopathology scores were significantly increased(P＜0.01), and the expression of occludin protein in colon tissue was significantly reduced (P＜0.01). Compared with DSS model group, BSP significantly alleviated body weight loss and colon shortening, and decrease DAI and histological scores, and up-regulated the expression of occludin protein in colon tissue of UC mice. Conclusions BSP alleviates inflammatory reactions of colonic mucosa in UC mice. The mechanism may be the improvement of intestinal epithelial barrier function mediated by increased expression of colonic mucosa occludin protein.

Key words: Bletilla striata polysaccharide, ulcerative colitis, intestinal epithelial barrier, occludin