Effect of 5-aminosalicylic acid on antioxidant mechanism and attenuation of proinflammatory cytokines in trinitrobenzene sulfonic acid-induced colitis in rats

AIM: To investigate the effect and mechanism of 5-aminosalicylic acid (5-ASA) in topical treatment on trinitrobenzene sulfonic acid (TNBS)-induced colitis in rats. METHODS: Colitis was induced by intracolonic administration of TNBS and was treated with 5-ASA at the dose of 100 mg·kg -1 for 2 weeks. Normal control group was administrated with normal saline and TNBS control group was treated with TNBS, not with 5-ASA. Macroscopic damage, histological changes and myeloperoxidase (MPO) activity were evaluated. Superoxide dismutase (SOD) activity and malondialdehyde (MDA) level in colonic mucosa were detected by kits. The expression of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) mRNAs in colonic mucosa was determined by a reverse transcription and polymerase chain reaction method. RESULTS: Compared with TNBS control group, the macroscopic and histological changes and MPO activity in 5-ASA treated groups were improved. SOD activity was increased and the level of MDA in colonic mucosa was reduced significantly. The expression of IL-1β and TNF-α mRNAs in colonic mucosa was also decreased significantly. CONCLUSION: 5-ASA enema can significantly ameliorate TNBS-induced colitis in rats via antioxidant mechanism and attenuation of proinflammatory cytokine expression.