不同时相的氙气预适应对小鼠肾脏缺血再灌注损伤的干预作用

Effect of xenon preconditioning for different durations on renal ischemia-reperfusion injury in mice

目的观察不同时间点的氙气预适应对小鼠肾脏缺血/再灌注(I/R)损伤的干预作用,并探讨其机制。方法采用双侧肾蒂夹闭法建立小鼠I/R模型,将36只小鼠随机分成6组:假手术组(Sham组)、I/R组、2h氙气预适应组(Xe-P2h组)、2h氮气预适应组(N2-P2h组)、24h氙气预适应组(Xe-P24h组)和24h氮气预适应组(N2-P24h组),每组6只。氙气或氮气预适应组小鼠在肾脏I/R术前2或24h予体积分数为0.7的氙气或氮气暴露2h。小鼠均于I/R 24h后留取血液、肾脏标本,收集24h尿量,分别检测肾功能和行肾组织病理学检查。采用Western印迹法检测单纯氙气(Xe组)或氮气(N2组)预适应后2、12、24h时肾脏缺氧诱导因子1α(HIF-1α)和血管内皮生长因子(VEGF)的表达。结果 I/R组、N2-P2h组和N2-P24h组小鼠I/R24h后的血清肌酐(sCr)和尿素氮(BUN)水平均显著高于Sham组(P值均<0.05),24h尿量均显著少于Sham组(P值均<0.05);Xe-P2h组和Xe-P24h组的sCr和BUN水平均显著低于I/R组(P值均<0.05),24h尿量均显著多于I/R组(P值均<0.05);Xe-P24h组的sCr和BUN水平显著低于Xe-P2h组(P值均<0.05)。I/R组、Xe-P2h组、N2-P2h组、Xe-P24h组和N2-P24h组的肾小管间质损伤评分均显著高于Sham组(P值均<0.05),Xe-P2h组和Xe-P24h组的肾小管间质损伤评分均显著低于I/R组(P值均<0.05),N2-P2h组、N2-P24h组的肾小管间质损伤评分均显著高于Xe-P24h组(P值均<0.05),Xe-P24h组的肾小管间质损伤评分显著低于Xe-P2h组(P<0.05)。Xe组小鼠的2和24h时肾脏HIF-1α、VEGF蛋白相对表达量均显著高于N2组同时间点(P值均<0.01);Xe组小鼠肾脏HIF-1α和VEGF的表达水平呈时间依赖性上调(P<0.05),在预适应2h时即开始上调,并于预适应24h时达到峰值。结论不同时相的氙气预适应均可以减轻小鼠肾脏I/R损伤,其机制可能是通过上调HIF-1α及其靶基因的表达。

Objective To investigate the effect of xenon preconditioning for different durations on renal ischemia-reperfusion injury in mice. Methods A total of 36 mice were randomly divided into six groups as follow （n = 6） ： sham operation group （Sham）, renal ischemia-reperfusion injury group （I/R）, 2 h xenon pretreatment group （Xe-P2h）, 2 h nitrogen pretreatment group （N2-P2h）, 24 h xenon pretreatment group （Xe-P24h） and 24 h nitrogen pretreatment group （N2-P24h）. Renal ischemia-reperfusion injury was performed by clamping bilateral pedicles for 30 min followed by reperfusion. In xenon and nitrogen pretreatment groups, mice were exposed to either 70% xenon or 70% nitrogen for 2 h or 24 h before the induction of renal ischemia-reperfusion injury. Blood sample and kidney were collected 24 h after ischemia-reperfusion. Urine volume of the mice was recorded during the experiment. Serum creatinine （sOr） and blood urea nitrogen （BUN） were examined. The protein expression of hypoxia-inducible factor 1α（HIF-lα） and vascular endothelial growth factor （VEGF） were analyzed by Western blotting. Results The levels of sCr and BUN were significantly increased 24 h after renal ischemia-reperfusion in I/R, N2-P2h and Nz-P24h groups, while 24-hour urine volume was significantly decreased when compared with Sham group （all P〈0.05）. The levels of sCr and BUN were significantly decreased in Xe-P2h and Xe-P24h groups, while 24-hour urine volume significantly increased when compared with I/R group （all P〈0.05）. The levels of sOr and BUN in Xe-P24h group were significantly lower than those in Xe-P2h group （both P〈0.05）. The tubular injury scores of I/R, Xe-P2h, N2-P2h, Xe-P24h and N2-P24h groups were significantly higher than that of Sham group （all P〈0.05）. The tubular injury scores of Xe-P2h and Xe-P24h groups were significantly lower than that of I/R group （both P〈0.05）. The tubular injury scores of N2-P2h and N2-P24h groups were significantly increased while the score of Xe-P24h group was significantly decreased as compared with Xe-P2h group （all P〈 0.05）. Compared with N2 group, xenon precondition upregulated HIF-1α and its downstream effector VEGF in a time-dependent manner, and the protein expression of HIF-lα and VEGF reached the peak at 24 h after xenon preconditioning. Conclusion Xenon pretreatments can alleviate renal ischemia-reperfusion injury in mice. The up-regulation of HIF-lα and its target gene may be involved in the protective effect. （Shanghai Med J, 2014, 37： 587-590）