Evaluation of lipid peroxidation levels on mucosa colonic cells afther application of hydrogen peroxide in enemas: experimental study in rats

摘要

> size="2" face="Verdana"> The use of rectal enemas with hydrogen peroxide (H₂O₂) determines the onset of severe colitis, sometimes with fatal evolution. It is possible that H₂O₂-induced colitis can occur by damage to the functional epithelial barrier of the colon by oxidative stress. Objective: The aim of present study was evaluate the levels of lipid peroxidation in cells of the colonic mucosa after instillation of H₂O₂ into the rectum excluded from fecal transit. Method: Twenty six male Wistar rats were undergone to proximal terminal colostomy in the descending colon and distal mucous fistula. The animals were randomized in two experimental groups according to the sacrifice was made two or four weeks after diversion of the fecal stream. Each experimental group was divided into two subgroups second application of enemas containing saline solution 0.9% or 3% H₂O₂ on alternate days. The diagnosis of colitis was established by histopathology study and the oxidative damage by tissue levels of malondialdehyde quantified by spectrophotometry. The results were analyzed with the Mann-Whitney and Kruskal-Wallis test, adopting a significance level of 5% (p 0.05). Results: The levels of malondialdehyde in colon segments irrigated with saline, with and without fecal stream after two and four weeks of irrigation were: 0.05 ± 0.006, 0.06 ± 0.006 and 0.05 ± 0.03, 0.08 ± 0.02, respectively. The levels of malondialdehyde in colon segments irrigated with H₂O₂, in the colon with and without fecal stream, after two and four weeks of irrigation were 0.070 ± 0.006, 0.077 and 0.052 ± 0.01 ± 0.01, 0.08 ± 0.04, respectively . After two weeks the levels of malondialdehyde were higher on animals irrigated with H₂O₂ than control group (p = 0.007 and p = 0.01, respectively). After four weeks there were no significant differences in malondialdehyde levels related with the time of irrigation. Conclusion: Rectal enemas with H₂O₂, may determine the onset of colitis by oxidative stress on epithelial cells of intestinal mucosa.