常压高浓度吸氧减轻大鼠肾缺血再灌注后肾小管上皮细胞凋亡

Normobaric hyperoxia alleviates renal tubular epithelial cell apoptosis induced by renal ischemia-reperfusion in rats

目的探讨常压高浓度吸氧对大鼠肾脏缺血再灌注后肾小管上皮细胞凋亡的影响及其机制。方法成年雄性SD大鼠18只, 均切除左侧肾脏建立孤肾模型, 1周后采用数字随机分配到3个组, 每组6只, 分别为假手术组(S组)、对照组(C组)和实验组(E组)。S组仅钝性分离右侧肾蒂, 但不予缺血处理;C组和E组均以动脉夹夹闭肾蒂致右肾缺血40 min。24 h后3组均置于密闭氧舱中, S组和C组吸入常规浓度氧气(21%), E组吸入高浓度氧气(50%~55%), 每天1次, 每次2 h, 持续7 d。术后第8天取大鼠右侧肾脏, 检测肾小管上皮细胞凋亡水平、丙二醛(MDA)和超氧化物歧化酶(SOD)含量、核因子E2相关因子2(Nrf2)的mRNA和蛋白表达水平、Nrf2在肾小管上皮细胞的表达水平。组间比较采用单因素方差分析。结果 C组和E组大鼠肾脏皮质中肾小管上皮细胞凋亡指数高于S组(12.18±1.82、3.96±0.99比0.74±0.20, F=145.003, P<0.05)。C组和E组大鼠肾脏组织MDA含量高于S组[(15.20±0.84)、(8.33±0.33) μmol/L比(5.53±0.38) μmol/L, F=465.303, P<0.05]。C组和E组大鼠肾脏组织SOD含量低于S组[(5.72±0.39)、(10.71±0.65) nmol/L比(14.20±0.52) nmol/L, F=381.495, P<0.05]。C组与E组中Nrf2 mRNA表达水平高于S组(3.01±0.28、6.23±0.60比1.00, F=469.948, P<0.05)。C组与E组中Nrf2蛋白表达水平高于S组(0.79±0.03、1.03±0.02比0.56±0.02, F=1 095.493, P<0.05)。C组与E组肾脏皮质中肾小管上皮细胞Nrf2吸光度(A)值高于S组(14.58±1.73、23.95±2.38比7.45±1.05, F=292.009, P<0.05)。结论常压高浓度吸氧能够减轻肾脏缺血再灌注损伤后肾小管上皮细胞凋亡。

Objective To investigate the effects of normobaric hyperoxia on renal tubular epithelial cell apoptosis induced by ischemia-reperfusion in rats and its related mechanism.Methods Totally,18 adult male SD rats were enrolled and their left kidney was excised.After one week,the animals were randomly assigned to 3 groups,6 rats in each group:sham-operated group(group S),control group(group C)and experimental group(group E).In group S,only the right renal pedicle was bluntly separated,but no ischemic treatment was given.Both group C and group E suffered from right renal ischemia for 40 min by clamping renal pedicle.After 24 h,the animals in all groups were placed in a sealed oxygen chamber.Rats in groups S and group C inhaled normal concentration oxygen(21%),and those in group E inhaled high concentration oxygen(50%-55%),once a day for 2 h each time for 7 days.On the 8th day after surgery,the right kidney of the rat was taken.The apoptosis index(AI),malondiadehyde(MDA)and superoxide dismutase(SOD)content was determined.The mRNA and protein expression of NF-E2-related factor 2(Nrf2)was detected.All data were expressed as mean±standard deviation(mean±SD),and comparison between groups was performed by one-way analysis of variance.Results As compared with group S,the AI of renal tubular epithelial cells in the renal cortex of rats in group C and group E increased,and that in group E was lower than in group C(12.18±1.82,3.96±0.99 vs.0.74±0.20,F=145.003,P<0.05).As compared with group S,the content of MDA in the kidney tissues of rats in group C and group E increased,but that in group E was lower than in group C[(15.20±0.84),(8.33±0.33)μmol/L vs.(5.53±0.38)μmol/L,F=465.303,P<0.05].As compared with group S,the SOD content in the kidney tissues of rats in group C and group E was reduced,and that in group E was higher than in group C[(5.72±0.39),(10.71±0.65)nmol/L vs.(14.20±0.52)nmol/L,F=381.495,P<0.05].As compared with group S,Nrf2 mRNA expression levels in group C and group E were increased,and those in group E were significantly higher than in group C(3.01±0.28,6.23±0.60 vs.1.00,F=469.948,P<0.05).As compared with group S,Nrf2 protein expression in group C and group E increased,and that in group E was significantly higher than in group C(0.79±0.03,1.03±0.02 vs.0.56±0.02,F=1095.493,P<0.05).As compared with group S,the Nrf2 absorbance(A)of renal tubular epithelial cells in the renal cortex of group C and group E increased,and that in group E was significantly higher than in group C(14.58±1.73,23.95±2.38 vs.7.45±1.05,F=292.009,P<0.05).Conclusion Normobaric hyperoxia can alleviate renal tubular epithelial cell apoptosis induced by reanl ischemia-reperfusion,and its mechanism may be related to the increase of Nrf2 expression in renal tissue so as to weaken the oxidative stress response.