Published online Oct 15, 2003. doi: 10.3748/wjg.v9.i10.2284
Revised: June 12, 2003
Accepted: June 19, 2003
Published online: October 15, 2003
AIM: To study the effects of Rheum tanguticum polysaccharide-1 (RTP-1) on ulcerative colitis in rats induced by 2, 4, 6-trinitrophene sulphonic acid (TNBS) and their possible mechanism.
METHODS: RTP1 (200 mg·kg-1, ig) extracted from Rheum tanguticum Maxim. ex Regel was administrated to rats with colitis induced by TNBS for 5 d, 7 d, 10 d and 14 d, respectively. The effects of RTP1 and dexamethasone (DX, 0.2 mg·kg-1, ig) were contrastively investigated. The MPO level and SOD activity were determined by chromatometry. The expansion and protein expression of CD4+ T lymphocytes isolated from colon mucosae and mesenteric lymph nodes of colitis rats were performed by immunohistochemical analysis and Western-blot methods.
RESULTS: Treatments of RTP1 (200 mg·kg-1, ig) significantly reduced diarrhea, mortality, colon mass, ulcer areas and MPO level in colon mucosae on days 5, 7, 10 and 14 (5.2 ± 1.4, 5.4 ± 0.7, 5.2 ± 1.8, P < 0.05. 3.4 ± 0.8, P < 0.01. 16.1 ± 12.1, P < 0.01. 31.8 ± 8.6, 17.7 ± 5.3, 12.7 ± 4.1, P < 0.05). The effects of RTP1 were similar to those noted above in DX group, but there were no immunosupressive effects of DX in RTP-1 group, such as body mass loss, thymus and spleen atrophy. The decreased number and down-regulated protein levels of CD4+ T cells isolated from the colon of colitis rats treated with RTP1 were found.
CONCLUSION: RTP1 shows significantly protective effects but lower side effects on rats with colitis induced by TNBS. The mechanism may be due to the resistance to over expansion of CD4.