The effect of Oren-gedoku-to on experimental colitis in rats

In Japan and China, Oren-gedoku-to (a complex mixture of ingredients derived from plants) has been used as a herbal medicine in the treatment of inflammatory and ulcerative diseases. In other countries salicylazosulfapyridine has been used to treat inflammatory bowel disease. In this study, we have compared the effect of Oren-gedoku-to with salicylazosulfapyridine on trinitrobenzene-sulphonic acid-induced colonic damage in rats, a model representative of ulcerative colitis and Crohn's disease in man. Oren-gedoku-to was administered orally for one or two weeks over a range of doses. Tissue damage scores, body weight, spleen weight, colon wet weight and colon wall thickness were measured, and colonic tissue levels of interleukin-8 (IL-8), leukotriene B4 (LTB4), prostaglandin E2 (PGE2), and myeloperoxidase activity were examined. The results indicated that Oren-gedoku-to was effective in the treatment of inflammatory bowel disease in the rat model. Histological observation showed a quicker healing process of the lesions, and a reduction of inflammatory cell infiltration following administration of Oren-gedoku-to. The precise mechanism of action for Oren-gedoku-to is still unclear; however, the reduction of IL-8, LTB4, and PGE2 observed suggests that the mechanism may be different from salicylazosulfapyridine (which has no effect on IL-8). There may be a potential benefit in offering combination therapy for the treatment of inflammatory bowel disease.