Glutathione supplementation improves oxidative damage in experimental colitis

Background. The pathogenesis of inflammatory bowel disease is due, in part, to enhanced free-radical production and reduced antioxidant potential in mucosa cells. Aim. We evaluated in a rat model of trinitrobenzensulphonic acid (TNBS) colitis to see whether parenteral administration of glutathione is able to improve mucosal oxidative damage at onset (study A) and during chronic phases of colitis (study 13). Methods. In study A, the rats were injected with a single dose of glutathione (200 mg/kg, i.p.) or saline (0,2 ml, i.p.) I h before colitis induction and killed I h later. In study 13, rats with induced colitis were treated with daily injection of glutathione (50 mg/kg, i.p.) or saline (0,2 ml, i.p.), and killed at 1, 2, 4 and 8 weeks. We evaluated on mucosal samples the macroscopic and histological damage and the oxidative stress assessed by the mucosal levels of lipoperoxides, malonyldialdehyde, glutathione and cysteine. Results. In study A, colitis induction caused a significant increase to the total histological score (p<0.05), lipoperoxide and malonyldialdehyde levels (p<0.001), but did not affect glutathione and cysteine content. Glutathione pre-treatment decreased both total histological score (p<0.05) and lipoperoxide and malonyidialdehyde values (p<0.001). In study 13, the extensive macroscopic and histological colonic damage induced by TNBS was accompanied by a reduction of glutathione and cysteine mucosal levels (p<0.01) and increased lipid peroxidation. Glutathione supplementation significantly improved colonic damage (p<0.01), restored glutathione and cysteine levels, and decreased, and even, if not totally, abolished lipid peroxidation (p<0.001). Conclusion. This paper further supports the pathogenic role of the imbalance in oxidant/ antioxidant content in inducing mucosal colonic damage. (C) 2003 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.