We have developed a simple and reproducible rat model of chronic colonic inflammation
by the intraluminal instillation of a solution containing a "barrier breaker" and
a hapten. Administration of the hapten 2,4,6-trinitrobenzenesulfonic acid (5-30 mg)
in 0.25 ml of 50% ethanol as the "barrier breaker" produced dose-dependent colonic
ulceration and inflammation. At a dose of 30 mg, trinitrobenzenesulfonic acid/ethanol-induced
ulceration and marked thickening of the bowel wall persisted for at least 8 wk. Histologically,
the inflammatory response included mucosal and submucosal infiltration by polymorphonuclear
leukocytes, macrophages, lymphocytes, connective tissue mast cells, and fibroblasts.
Granulomas were observed in 57% of the rats killed 3 wk after induction of inflammation.
Langhan's-type giant cells were also observed. Segmental ulceration and inflammation
were common. The characteristics and relatively long duration of inflammation and
ulceration induced in this model afford an opportunity to study the pathophysiology
of colonic inflammatory disease in a specifically controlled fashion, and to evaluate
new treatments potentially applicable to inflammatory bowel disease in humans.