The importance of oxygen free radicals in the etiopathogenesis of diversion colitis in rats.
OBJECTIVE
Quantify the levels of oxidative DNA damage of epithelial colon cells comparing segments with and without fecal stream.


METHODS
Sixty Wistar rats were subjected to deviation of fecal stream by proximal colostomy and a distal mucosal fistula. Animals were divided into three experimental groups that were sacrificed 6, 12 and 24 weeks after surgery. In each experimental group, five animals underwent laparotomy without intestinal deviation (sham subgroup). The diagnosis of colitis was made by histopathological analysis and the inflammatory activity index by graduated scale. The neutrophil infiltration was determined by myeloperoxidase tissue levels and the intensity of oxidative DNA damage by comet assay. The Mann-Withney and Student t test were used to compare the results among experimental subgroups and the Kruskal-Wallis test for variance analysis, adopting a significance level of 5% (p<0.05).


RESULTS
Colon segments without fecal stream was shown higher histological inflammatory score of the colon wall after 12 and 24 weeks (p=0.001) that increased with the time of diversion (p=0.01). The activity of myeloperoxidase in segments without fecal stream decreased with the time (p=0.001). Oxidative DNA damage levels were significantly higher in the segments without fecal stream, (p=0.0001), independent of time of colon diversion, and increase with the time (p=0.0007).


CONCLUSIONS
Colon segments without fecal stream showed high levels of oxidative DNA damage related to histological alterations observed in diversion colitis. The levels of oxidative DNA damage in segments devoid of the fecal stream increase with the time of intestinal exclusion.
Martinez
Carlos Augusto Real
CA
Santa Casa Faculty of Medical Sciences, USF, Sao Paulo, Brazil. caomartinez@uol.com.br
Ribeiro
Marcelo Lima
ML
Gambero
Alessandra
A
Miranda
Daniel Duarte da Conceição
DD
Pereira
José Aires
JA
Nadal
Sidney Roberto
SR
D000818:Animals; D003092:Colitis / Q000235:genetics* / Q000473:pathology; D004249:DNA Damage; D004195:Disease Models, Animal; D005243:Feces; D005609:Free Radicals / Q000032:analysis; D005772:Gastrointestinal Transit / Q000502:physiology*; D007413:Intestinal Mucosa / Q000473:pathology; D008297:Male; D018384:Oxidative Stress / Q000502:physiology*; D009195:Peroxidase / Q000032:analysis; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D018709:Statistics, Nonparametric
D005609:Free Radicals; D009195:Peroxidase