AIM:Irritable bowel syndrome(IBS)is a functional boweldisorder characterized by visceral hypersensitivity andaltered bowel motility.There is increasing evidencesuggesting the role of inflammation in the pathogenesis ofIBS,which addresses the possibility that formerly establishedrat model of colitis could be used as an IBS model after theinflammation subsided.METHODS:Colitis was induced by intracolonic instillationof 4% acetic acid in male Sprague-Dawley rats.The extentof inflammation was assessed by histological examinationand myeloperoxidase(MPO)activity assay.After subsidenceof colitis,the rats were subjected to rectal distension andrestraint stress,then the abdominal withdrawal reflex andthe number of stress-induced fecal output were measured,respectively.RESULTS:At 2 days post-induction of colitis,the colonshowed characteristic inflammatory changes in histology and8-fold increase in MPO activity.At 7 days post-induction ofcolitis,the histological features and MPO activity returnedto normal.The rats at 7 days post-induction of colitis showedhypersensitive response to rectal distension without anaccompaning change in rectal compliance,and defecatedmore stools than control animals when under stress.CONCLUSION: These results concur largely with the characteristic features of IBS, visceral hypersensitivity and altered defecation pattern in the absence of detectable disease, suggesting that this animal model is a methodologically convenient and useful model for studying a subset of IBS. AIM: Irritable bowel syndrome (IBS) is a functional boweldisorder characterized by visceral hypersensitivity and altered bowel motility. There is increasing evidences that the role of inflammation in the pathogenesis of IBS, which addresses the possibility that previously established model of colitis could be used as an IBS model after the inflammation subsided. METHODS: Colitis was induced by intracolonic instillation of 4% acetic acid in male Sprague-Dawley rats. The extent of inflammation was assessed by histological examination and myeloperoxidase (MPO) activity assay. After subsidence of colitis, the rats were subjected to rectal distension andrestraint stress, then the abdominal withdrawal reflex and the number of stress-induced fecal output were measured, respectively .RESULTS: At 2 days post-induction of colitis, the colonshowed characteristic inflammatory changes in histology and 8-fold increase in MPO activity. At 7 days post -induction ofcolitis, the histological features and MPO activity returnedt o normal.The rats at 7 days post-induction of colitis showed hypersensitive response to rectal distension without anaccompaning change in rectal compliance, and defecatedmore stools than control animals when under stress. CONCLUSION: These results concur largely with the characteristic features of IBS, visceral hypersensitivity and altered defecation pattern in the absence of detectable disease, suggesting that this animal model is a methodologically convenient and useful model for studying a subset of IBS.