ELSEVIER BRIEF COMMUNICATION Hapten-Induced Chronic Colitis in the Rat: Alternatives to Trinitrobenzene Sulfonic Acid John L. Wallace, Tai Le, Lisa Carter, Caroline B. Appleyard, and Paul L. Beck Intestinal Disease Research Unit, Faculty of Medicine, University of Calgary, Alberta, Canada Hapten-induced colitis is a widely used model for the study of the intestinal inflammation and for the testing of novel therapies. However, the hapten utilized in this model, trinitrobenzene sulfonic acid, is difficult to obtain in some countries. We therefore compared this hapten to two structurally related haptens to determine if they could be substituted for trinitrobenzene sulfonic acid in terms of inducing chronic colitis in the rat. Rats received one of the three haptens intracolonically, and the severity of colonic inflammation was assessed 3 and 14 days later. Dinitrobenzene sulfonic acid produced colonic inflammation and ulceration that was indistinguishable from that induced by trinitrobenzene sulfonic acid at both time points. On the other hand, dinitrochlorobenzene produced acute colitis (3 days postadministration), but by Day 14 this inflammation had subsided. Dinitrobenzene sulfonic acid and trinitrobenzene sulfonic acid produced comparable levels of granulocyte infiltration into the colon (as measured by tissue myeloperoxidase activity and histology) at both time points. These studies suggest that for studies of up to at least 2 weeks in duration, dinitrobenzene sulfonic acid and trinitrobenzene sulfonic acid produce comparable levels of colonic inflammation. Dinitroben- zene sulfonic acid therefore offers a useful and less expensive alternative to trinitrobenzene sulfonic acid. Key Words: Inflammatory bowel disease; Animal model; Inflammation Introduction Many animal models of inflammatory bowel disease (IBD) have been developed over the past 30 years and are widely used to investigate the pathogenesis of intes- tinal inflammation and as models in which novel thera- peutic regimens can be tested (Rim and Berstad, 1992). Among the most commonly used animal models for chronic colitis is the “hapten model”, originally de- scribed by Morris et al. (1989). This model involves a single, intracolonic administration of a hapten, trinitro- benzenesulfonic acid (TNBS), dissolved in a vehicle of 30%-50% (vol/vol) ethanol. This treatment results in the formation of colonic ulcers that persist for up to 8 weeks. Moreover, the model is characterized by exten- sive, transmural granulomatous inflammation of the colon that shares many histopathological features with Address reprint requests to Dr. John L. Wallace, Department of Pharmacology & Therapeutics, University of Calgary, Calgary, Al- berta, T2N 4N1, Canada. Received October 4,1994; revised and accepted December 1,1994. Journal of Pharmacological and Toxicological Methods 33, 237-239 (1995) 0 1995 Elsevier Science Inc. 655 Avenue of the Americas, New York, NY 10010 Crohn’s disease. The TNBS model is simple and repro- ducible, and it exhibits many, but not all, of the features of human IBD. In recent years, some suppliers of TNBS have either discontinued producing it entirely, or produced and sold it only as a dilute solution. The reason for this change in production is that TNBS, as a derivative of picric acid, is potentially explosive. Unfortunately, the available solu- tions of TNBS are too dilute for use in inducing colitis. For these reasons, we undertook the present study in which we compared two structurally similar haptens to TNBS in terms of their ability to induce colonic inflam- mation. Our results suggest that dinitrobenzene sulfonic acid (DNBS), which is readily available from a number of commercial sources, is as effective as TNBS for inducing chronic colitis in the rat. Methods and Materials Male Wistar rats obtained from Charles River Breed- ing Farms (Montreal, Quebec) and weighing 175-200 g 1056~8719/95/$9.50 SSDI 1056-8719(95)00001-X