The effects of oxidative DNA damage and mutations in the p53 protein on cells of the colonic mucosa with and without the fecal stream: an experimental study in rats.
OBJECTIVE
The aim of this study was to investigate the levels of oxidative DNA damage and p53 mutations in an experimental model of diversion colitis.


METHODS
Sixty rats were divided into three groups with 20 animals in accordance with the sacrifice was carried out 6, 12 and 18 weeks. For each group, 15 animals were subjected to diversion of the fecal stream through colostomy in the left proximal colon and distal mucous fistula (experimental group), and five to a laparotomy without deviation of the fecal stream (control group). The presence of colitis was evaluated by inflammatory grading scale. Mutations in the p53 protein were evaluated by immunohistochemistry with primary antibody with cross-reactivity for rats. The oxidative DNA damage was measured using the comet assay. To statistical analysis were used the Student's t, Mann-Whitney and Kruskal-Wallis test adopting a significance level of 5% (p < 0.05).


RESULTS
Colon segments without fecal stream showed greater degree of inflammation when compared to animals with preserved fecal stream (p = 0.01). The levels of oxidative stress were significantly higher in segments without fecal stream (p < 0.0001) and increased with the time of fecal diversion (p = 0.007). The levels of oxidative DNA damage are directly related to tissue degree of inflammation. There were no mutations in the p53 protein in the segments without fecal stream regardless of time of exclusion considered.


CONCLUSIONS
Despite higher levels of oxidative damage to nuclear DNA on segments without fecal stream that developed colitis mutations in the p53 protein were not detected.
Martinez
Carlos Augusto Real
CA
Department of Surgery, São Francisco Medical School, Santo André, Brazil. carmartinez@uol.com.br
Bartocci
Priscila Cecília Mendes
PC
do Carmo
Carlos Vieira
CV
Pereira
José Aires
JA
Miranda
Daniel Duarte da Conceição
DD
Ribeiro
Marcelo Lima
ML
D000818:Animals; D003092:Colitis / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D003106:Colon / Q000378:metabolism / Q000473:pathology; D020552:Comet Assay; D004249:DNA Damage; D004195:Disease Models, Animal; D005243:Feces; D007150:Immunohistochemistry; D007413:Intestinal Mucosa / Q000378:metabolism* / Q000473:pathology; D008297:Male; D009154:Mutation; D018384:Oxidative Stress; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000235:genetics* / Q000378:metabolism
D017382:Reactive Oxygen Species; D016159:Tumor Suppressor Protein p53