Evaluation of the usefulness of colonoscopy with mucosal biopsies in the follow-up of TNBS-induced colitis in rats.

Animal models are required for research regarding the pathogenesis and efficacy of anti-inflammatory agents in inflammatory bowel disease (IBD). Trinitrobenzene sulfonic acid (TNBS)-induced colitis closely mimics Crohn's disease. The present study was undertaken in order to determine the reliability of following the inflammatory course of TNBS-induced colitis using colonoscopy together with biopsy samples obtained during the examination. In this study we used 20 adult male Wistar rats, with a mean weight of 201.9 g. The rats were divided into two groups, control and TNBS, with ten rats in each group. Following the induction of TNBS colitis, the rats underwent colonoscopy with mucosal biopsies. At the end of the experiment, the rats were sacrificed and whole-wall colonic samples were obtained. The degree of inflammation was assessed endoscopically, macroscopically and microscopically. There was no significant change in the body weight of the control group but significant weight loss was observed in the TNBS group. Examination of the control group did not reveal any inflammation. Severe colitis was observed in the TNBS-induced colitis rats, as assessed endoscopically, macroscopically and microscopically. The endoscopic inflammation score obtained through colonoscopy examinations correlated with that obtained macroscopically, and those obtained microscopically from the whole-wall colon and biopsy samples collected during the colonoscopy. Moreover, the inflammation scores obtained from the whole-wall colon and biopsy samples collected during colonoscopy correlated markedly. In conclusion, colonoscopy is a reliable method for following up the course of inflammation in experimentally induced colitis. Although biopsy samples collected during colonoscopies may be used to assess the degree of inflammation, whole-wall samples are superior in this regard.