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目的:观察二甲基精氨酸二甲胺水解酶2(dimethylarginine dimethylaminohydrolase 2,DDAH2)在糖尿病脓毒症机体中的表达变化,探讨血管内皮功能损害的发生机制。方法:64只Wistar大鼠随机分为正常对照组、单纯脓毒症组、糖尿病组、糖尿病脓毒症组,每组16只。免疫组织化学方法观察肺组织结构变化及DDAH2表达的分布变化。Griess法测定血清及肺组织一氧化氮(nitrite oxide,NO)含量,real-time PCR测定肺组织DDAH2 mRNA水平。结果:免疫组织化学显示糖尿病组大鼠肺组织平均光密度值(average optical density value,AOV)无明显变化,RT-PCR显示DDAH2 mRNA表达水平低于正常对照组(P<0.05);脂多糖(lipopolysaccharides,LPS)腹腔注射后,单独脓毒症组和糖尿病脓毒症组肺组织DDAH2 AOV值及mRNA表达较正常对照组均明显降低(均P<0.01);且糖尿病脓毒症组AOV值低于单纯脓毒症组(P<0.01),DDAH2 mRNA表达亦低于单纯脓毒症组(P<0.05)。糖尿病脓毒症组及单纯脓毒症组血清及肺组织中NO水平均增高,血清测定前者低于后者(P<0.05),但肺组织中前者高于后者近2倍(P<0.05)。结论:脓毒症肺表现为DDAH2表达下调,糖尿病脓毒症肺组织表现为DDAH2表达更为明显下调,提示存在更为严重的血管内皮细胞损害,因此DDAH2表达下调可能参与脓毒症糖尿病机体肺损伤的发生。
Objective: To observe the expression of dimethylarginine dimethylaminohydrolase 2 (DDAH2) in diabetic sepsis and to explore the mechanism of vascular endothelial dysfunction. Methods: Sixty-four Wistar rats were randomly divided into normal control group, simple sepsis group, diabetic group and diabetic sepsis group, 16 in each group. The changes of lung tissue structure and the distribution of DDAH2 expression were observed by immunohistochemistry. The content of nitrite (NO) in serum and lung tissue was determined by Griess method, and the level of DDAH2 mRNA in lung tissue was determined by real-time PCR. Results: Immunohistochemistry showed no significant change in the average optical density value (AOV) of lung tissue in diabetic rats, and the expression of DDAH2 mRNA in the diabetic group was lower than that in the normal control group by RT-PCR (P <0.05) (P <0.01). The AOV value and the mRNA expression of DDAH2 in the sepsis group and diabetic sepsis group were significantly lower than those in the normal control group In the sepsis group (P <0.01), DDAH2 mRNA expression was also lower than that in the sepsis group (P <0.05). Serum and lung tissue of diabetic sepsis group and simple sepsis group NO levels were increased, the former was lower than the latter (P <0.05), but the former was higher than the latter two times (P <0.05 ). Conclusion: The expression of DDAH2 is down-regulated in the lung of septic rats. The expression of DDAH2 in the lung tissue of diabetic sepsis is more obviously down-regulated, which indicates that there is more serious vascular endothelial cell damage. Therefore, the down-regulation of DDAH2 may be involved in the pathogenesis of sepsis Injury occurred.