Crocetin ameliorates TNBS inducd chronic colitis in rats by inhibiting expression of cyclooxygenase-2

The aim of this study was to explore the possible mechanisms of crocetin affecting rat colitis induced by 2, 4, 6-trinitrobenzene sulfonic acid (TNBS). Rats were treated with crocetin. 5-aminosaliylic acid was used as a positive control. Change of body weight was evaluated. Leukocyte infiltration was detected by myeloperoxidase activity assay. The expression of cyclooxygenase-2 was detected by RT-PCR and Western blot. Inflammatory cytokines were determined by RT-PCR. Local concentration of prostaglandin E2 in colon mucosa was determined by ELISA. Crocetin decreased the macroscopic scores and myeloperoxidase activity. Crocetin also reduced the expression of COX-2 and inflammation cytokines. In addition, treatment with crocetin increased the PGE2 level. Moreover, the effects of crocetin were almost comparable with that of positive control drug. Crocetin has therapeutic effects on TNBS-induced colitis; the mechanisms seem to be related to COX-2 inhibition and PGE2 improvement.