Expressions Of Collagen Fibers And Osteopontin In The Colon And The Effects Of 5-asa In Rats With Ulcerative Colitis Induced By Dextran Sulfate Sodium

BACKGROUD: Ulcerative colitis (UC) in rats induced by dextran sulfate sodium (DSS) had similar pathological and clinical features to those in human. While the intestinal wall got fibrosis, the content of collagen fibers increased, and osteopontin (OPN) involved in the progression of organic fibrosis.OBJECTIVE: To detect the content of collagen and the expressions of OPN in the colon in rats with DSS-induced UC, and to observe the effect of 5-ASA on them.METHODS: Forty male SD rats were randomly divided into group A (control group,n=10) and group B (model group,n=30) in a 1:3 ratio.The rats in group A drunk sterile distilled water freedomly, and in group B were given with 3% DSS for 7 days and then with distilled water for another 10 days. The procedure was repeated after 17-days. After 7-day intragastric administration of 3% DSS, the rats in group B were randomly subdivided into 3 subgroups(n=10): group B₁ (model control), group B₂ (early administration of 5-ASA), group B₃ (late administration of 5-ASA) at the 8th day. The rats in group B₂ and in group B₃ were intragastric administration of 5-ASA of 210mg/kg in the 8th-21th days and 25th-38th days respectively. The general conditions, such as bloody stool, weight, were observed. At the 39^th day, all rats were killed, and the colon tissues were collected for HE staining, collagen fibers staining (by picric acid Sirius red staining), and osteopontin staining (by immunohisto- chemistry semi-quantitative analysis).RESULT: The rats in the group B had loose or bloody stool, and weight loss. HE staining showed significant infiltration of inflammatory cells, erosion or ulcer formation in the colonic mucosa in group B. The relative content of collagen(%)in group B(B₁:22.25%±6.13%,B₂:20.41%±4.56%,B₃:20.10%±4.78%) was significantly higher than in group A(13.29%±4.77%,P<0.01). However, there was not a difference among the three subgroups in group B (p>0.30). The OPN expressions in the mucosal epithelium and the lamina propria in group B were significantly higher than in group A (P<0.05,respectively). However, there also was not a difference among the three subgroups in group B (p> 0.05).CONCLUSION: There showed a tendency of intestinal fibrosis in rats with DSS-induced ulcerative colitis, and OPN may involve in the progression of intestinal fibrosis. A standard dose of 5-ASA had no preventive effect on the fibrosis.