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.