氧化应激在新生大鼠常压高体积分数氧致脑损伤发生中的作用

Effect of Oxidative Stress in Pathogenesis of Normobaric Hyperoxia-Induced Brain Injury in Newborn Rats

目的探讨氧化应激在7日龄新生大鼠高体积分数氧（高氧）性脑损伤发生中的作用。方法体质量12～18g的7日龄SD大鼠42只，随机分为空气组和高氧组。高氧组与其乳母一起置于氧箱中，调节氧流量（3L／min），使箱内氧体积分数维持（800±50）mL／L，用数字式测氧仪进行监测。空气组置于同一室内空气中，氧体积分数为210mL／L，饲养条件与高氧组相同。高氧／空气开始暴露30min后，各取3只大鼠，麻醉后采血，行动脉血气分析。高氧／空气暴露12h后2组大鼠各处死8只，化学比色法检测其脑组织还原型谷胱甘肽（GSH）、氧化型谷胱甘肽（GSSG）、GSSG／GSH、超氧化物歧化酶（SOD）、丙二醛（MDA）水平。高氧／空气暴露12h后2组各处死10只大鼠，取其脑组织常规脱水、包埋、切片（经海马），脱氧核糖核苷酸末端转移酶介导的原位缺口末端标记法观察脑组织细胞凋亡指数。结果空气组平均动脉血氧分压[pa（O2）]为（87．0±2．71）mmHg（1mmHg=0．133kPa），高氧组为（219．0±10．7）mmHg，高氧组明显高于空气组[（87．0±2．71）mmHg]（P〈0．05）。高氧组暴露12h脑细胞凋亡指数[（39．20±7．59）％]较空气组[（4．50±1．87）％]显著增加（P〈0．01）。高氧暴露12h组GSH[（0．994±0．230）μmol／g]较空气组[（1．210±0．210）μmoL／g]明显下降（P〈0．05），高氧组暴露12h SOD[（124．60±4．14）×10^3 U／g]也较空气组[（145．0±6．62）×10^3 U／g]明显下降（P〈0．01）；高氧组GSSG[（0．0283±0．0043）μmol／g]、GSSG／GSH（0．0296±0．0045）、MDA[（5．21±0．41）μmol／g]均较空气组[（0．0212±0．0029）μmol／g，0．0181±0．0031，（4．85±0．25）μmol／g]显著升高（Pa〈0．05）。结论常压高氧可引起新生大鼠脑细胞的凋亡及氧化应激，氧化应激与高氧性脑损伤密切相关。

Objective To explore the effect of oxidative stress in pathogenesis of normobarie hyperoxia - induced brain injury in newborn rats. Methods Forty - two 7 - day - old SD rats weighting 12 - 18 g were randomly assigned into 2 groups：hyperoxia group and air group. For hyperoxia group, the pups were kept in a chamber containing （800±50 ） mL/L of oxygen （3 L/min ） with their dams. The oxygen concentration was monitored with digital oxygen monitor. Air group was placed in air environment with oxygen 210 mL/L. Three rats in each group were used after exposure to air/oxygen for 30 minutes to determine blood oxygen content. Eight rat pups were sacrificed after exposure to oxygen for 12 hours. The brains were used to detect the level of reduced glutathione （GSH）,oxidized glutathione （GSSG）,GSSG/GSH, superoxide dismutase （SOD）, and malondialdehyde（MDA） by chemi- colorimetric. Ten rats in each group were killed in each group after expose oxygen for 12 hours. The brains were dehydrated and embedded for terminal deoxynucleotidyl transferase biotin - dUTP nick end labeling staining. Apoptotic index was calculated. All the data were analyzed with SPSS 10.0 software. Results The pa （ O2 ） of hyperoxia group [ （219.0±10.7） mmHg, 1 mmHg = 0.133 kPa ] was significantly higher than that of air group [ （ 87.0 ± 2.71 ） mmHg ] （ P 〈 0. 05 ）. The apoptotic index in hyperoxia group [ （ 39.20 ±7.59 ） % ] was significantly higher than that of air group [ （4.50±1.87 ） % ] （ P 〈 0. 01 ）. The concentrations of GSH [ （0. 994 ± 0. 230） μmol/g ], and SOD [ （ 124.60 ± 4.14 ） ×10^3 U/g ] in hyperoxia group were significantly lower than those in air group[ （ 1. 210 ± 0. 210 ） μmol/g, （ 145.0 ±6.62 ） ×10^3 U/g ] （ Pa 〈 0.05 ）, while concentration of GSSG [ （0. 028 3±0. 004 3 ） μmol/g] ,MDA[ （5.21 ± 0.41 ） μmol/g] and the ratio GSSG to GSH （0. 029 6 ± 0. 004 5 ） were higher than those of air group [ （0.021 2±0.002 9） μmol/g, （4. 85±0.25） μmol/g, （0. 018 1±0.003 1） ] （Pa 〈0.05）. Conclusions Normobarie - hyperoxia can induce neural cell apoptosis in newborn rat. Oxidative stress was closely related to the pathogenesis of hypoeroxia - induced brain injury.