Martinez Carlos Augusto Real, Bartocci Priscila Cecília Mendes, do Carmo Carlos Vieira, Pereira José Aires, Miranda Daniel Duarte da Conceição, Ribeiro Marcelo Lima
Department of Surgery, São Francisco Medical School, Santo André, Brazil.
Scand J Gastroenterol. 2010 Jun;45(6):714-24. doi: 10.3109/00365521003650743.
The aim of this study was to investigate the levels of oxidative DNA damage and p53 mutations in an experimental model of diversion colitis.
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).
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.
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.
本研究旨在调查改道性结肠炎实验模型中氧化性DNA损伤水平和p53基因突变情况。
60只大鼠根据处死时间分为三组，每组20只，处死时间分别为6周、12周和18周。每组中，15只动物通过在左近端结肠进行结肠造口术和远端黏液瘘来使粪便改道（实验组），5只进行未改变粪便流向的剖腹手术（对照组）。通过炎症分级量表评估结肠炎的存在情况。使用对大鼠具有交叉反应性的一抗通过免疫组织化学评估p53蛋白中的突变。使用彗星试验测量氧化性DNA损伤。采用Student's t检验、Mann-Whitney检验和Kruskal-Wallis检验进行统计分析，显著性水平为5%（p < 0.05）。
与粪便流向未改变的动物相比，粪便改道的结肠段显示出更严重的炎症程度（p = 0.01）。粪便改道的结肠段中氧化应激水平显著更高（p < 0.0001），并且随着粪便改道时间增加（p = 0.007）。氧化性DNA损伤水平与组织炎症程度直接相关。无论考虑的排除时间如何，粪便改道的结肠段中p53蛋白均未发生突变。
尽管发生结肠炎的粪便改道结肠段中核DNA的氧化损伤水平较高，但未检测到p53蛋白中的突变。
