Cigarette smoke aggravates experimental colitis in rats

Background Be Aims: Tobacco smoking has a complex effect on intestinal inflammation, being protective in ulcerative colitis, whereas it aggravates Crohn's disease. The beneficial effect of smoking has been attributed to nicotine, but the mechanisms underlying the adverse effect are still under investigation. The aim of this study was to examine the effect of cigarette smoking on experimental colitis in rats and to investigate the underlying mechanism. Methods: Rats were exposed daily to cigarette smoke by means of a specialized smoking chamber. Control rats were placed in the same chamber without introducing smoke. In parallel experiments, rats received the ganglionic blocker hexamethonium before smoke exposure. After 2 weeks, colitis was induced by dinitrobenzenesulfonic acid (DNBS), and inflammation was assessed 3 days later. Results: Exposure to cigarette smoke significantly increased macroscopic and histological damages as well as myeloperoxidase activity compared with sham-treated controls. Treatment with hexamethonium before smoking reversed the effect of the smoke on the colitis, improving all parameters. Conclusions: Exposure to cigarette smoke aggravates DNBS-induced colitis in the rat. This effect is reversed by hexamethonium, suggesting that a neural pathway is involved.