Cigarette smoke aggravates experimental colitis in rats

Background Be Aims: Tobacco smoking has a complex effect on intestinal infl ammation, being protective in ulcerative colitis, whereas it aggravates Cro hn's disease. The beneficial effect of smoking has been attributed to nicot ine, but the mechanisms underlying the adverse effect are still under inves tigation. The aim of this study was to examine the effect of cigarette smok ing on experimental colitis in rats and to investigate the underlying mecha nism. Methods: Rats were exposed daily to cigarette smoke by means of a spe cialized smoking chamber. Control rats were placed in the same chamber with out introducing smoke. In parallel experiments, rats received the ganglioni c blocker hexamethonium before smoke exposure. After 2 weeks, colitis was i nduced 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 c ompared with sham-treated controls. Treatment with hexamethonium before smo king reversed the effect of the smoke on the colitis, improving all paramet ers. Conclusions: Exposure to cigarette smoke aggravates DNBS-induced colit is in the rat. This effect is reversed by hexamethonium, suggesting that a neural pathway is involved.