Abstract
Background: Ulcerative Colitis (UC) is an inflammatory bowel disorder that represents a common health problem. 5 Hydroxy Tryptamine 3 (5-HT3) receptors are widely distributed in the gut and 5-HT3 receptor antagonists have been reported to have anti-inflammatory effects.
Objectives: Evaluates the possible effects of ondansetron, mesalazine and their combination in oxazolone induced-colitis in albino rats.
Methods: This experiment was performed on 50 male Wister albino rats divided into 5 equal groups; (Group I) control group received intrarectal vehicle of ethanol then oral 0.5% carboxymethyl cellulose daily for 21 days, (Group II) untreated induced-colitis group received intrarectal oxazolone then oral 0.5% carboxymethyl cellulose daily, (Group III) oxazolone induced-colitis rats were treated by mesalazine (100mg/kg/day by oral gavage) for 21 days, (Group IV) oxazolone induced-colitis rats were treated by ondansetron (2mg/kg/day) by intraperitoneal injection for 21 days, (Group V) oxazolone induced-colitis rats were treated by mesalazine and ondansetron in the same dosage regimen. Animal body weights, occurrence of diarrhea, and rectal bleeding were recorded daily over the experiment to calculate Disease Activity Index (DAI), at the end of the study all rats were sacrificed, portions of distal colons were dissected and proc-essed for assessment of myeloperoxidase activity, tumor necrosis factor-a  levels, caspase-3 activity, histopathological examination and immunohistochemistry of Toll Like Receptor 2 (TLR2).
Results: The present study showed that treatment with ondansetron produce significant decrease in the whole studied parameters, also its combination with mesalazine produce significant decrease in all studied parameters when compared to untreated induced-colitis group as well as produce better response than each drug alone.
Conclusion: These findings suggest that ondansetron produce promising effects in oxazolone induced-colitis which mimics UC in human. Its combination with mesalazine exhib-ited synergistic effects superior to each monotherapy. It could be recommended to verify these results in further clinical studies.