Endoscopic Scoring System for Experimental Colitis with Trinitrobenzene Sulfonic Acid in Rats

: Experimental colitis models require serial sacrifice of animals to confirm the evolution of the inflammatory process. Endoscopy may possibly enable us to detect sequential changes in the lesions throughout the inflammatory process without killing animals. Using rat colitis induced with trinitrobenzene sulfonic acid (TNBS) after the study by Morris et al. the accuracy of endoscopic examination was investigated by comparing endoscopic findings with histologic findings. A polyethylene catheter was rectally inserted into rats’(Fischer, 6W male) colon. After intraluminal administration of 25 mg TNBS dissolved in 0.5 ml of 50% ethanol, each animal was kept in the tail-up position for one minute. Colonic changes were examined weekly with an Olympus BF-3C20. It took about 3 min to complete the observation per rat. We offered a novel endoscopic and histologic scoring system. The endoscopic score mainly reflected the size of the ulcers occupying the lumen and the histologic score the sizel depth of the ulcers and the degree of acute inflammation in the colonic mucosa. A highly significant (r = 0.71, p<0.01) linear correlation was observed between the endoscopic and histologic scores. This system may allow us to detect potential therapeutic agents or to investigate the mechanism underlying colitis in the human counterpart, such as Crohn 's disease, without killing laboratory animals.