Protective effect of angelica sinensis polysaccharide on experimental immunological colon injury in rats

AIM: To study the effect of angelica sinensis polysaccharide (ASP) on immunological colon injury and its mechanisms in rats. METHODS: Immunological colitis model of rats was induced by intracolon enema with 2, 4, 6-trinitrobenzene sulfonic acid (TNBS) and ethanol. The experimental animals were randomly divided into normal control, model control, 5-aminosalicylic acid therapy groups and three doses of ASP therapy groups. The 6 groups were treated intracolonically with normal saline, normal saline, 5-aminosalicylic acid (100 mg.kg(-1)), and ASP daily (8:00 am) at the doses of 200, 400 and 800 mg.kg(-1) respectively for 21 days 7 d following induction of colitis. The rat colon mucosa damage index (CMDI), the histopathological score (HS), the score of occult blood test (OBT), and the colonic MPO activity were evaluated. The levels of SOD, MDA, NO, TNF-alpha, IL-2 and IL-10 in colonic tissues were detected biochemically and immunoradiometrically. The expressions of TGF-beta and EGF in colonic tissues were also determined immunochemically. RESULTS: Enhanced colonic mucosal injury, inflammatory response and oxidative stress were observed in colitis rats, which manifested as significant increases of CMDI, HS, OBT, MPO activity, MDA and NO contents, as well as the levels of TNF-alpha and IL-2 in colonic tissues, although colonic TGF-beta protein expression, SOD activity and IL-10 content were significantly decreased compared with the normal control (P<0.01). However, these parameters were found to be significantly ameliorated in colitis rats treated intracolonically with ASP at the doses of 400 and 800 mg.kg(-1) (P<0.05-0.01). Meantime, colonic EGF protein expression in colitis rats was remarkably up-regulated. CONCLUSION: ASP has a protective effect on immunological colon injury induced by TNBS and ethanol enema in rats, which was probably due to the mechanism of antioxidation, immunomodulation and promotion of wound repair.