高压氧对大鼠脑缺血区线粒体氧自由基影响的实验研究

目的:研究高压氧(HBO)对大鼠脑缺血区线粒体氧自由基及抗自由基酶的影响.方法:参照改良的Koizumi方法,在激光多普勒 血流仪监测局部脑血流的条件下,建立线栓法大鼠局灶性脑缺血模型,缺血90 min后再灌注 ,缺血后3 h高压氧治疗(3个标准大气压,1 h),缺血后24 h分别取缺血核心区和半暗区脑组织,差速离心提取线粒体,进行超氧阴离子自由基(O2()/(·) )生成速率、H2O2含量、丙二醛(MDA)含量测定,以及线粒体超氧化歧 化酶(SOD)、谷胱甘肽过氧化物酶(GSH-PX)和还原型谷胱甘肽(GSH)含量测定. 结果:脑缺血再灌注24 h后缺血半暗区和核心区线粒体的H2O2、O2()/( ·)、MDA的含量较正常对照组明显增加,而SOD、GSH-PX活性以及GSH的含量较正常 对照组明显下降(P<0.05).经HBO治疗后,缺血半暗区线粒体O2(含量增加(P<0.05),SOD活性提高(P<0.05),而MDA含量减少( P<0.05);缺血核心区线粒体O2()/(·)含量增加(P<0. 05),SOD活性提高(P<0.05),但MDA含量不变.HBO治疗对脑缺血区的H2O 2、GSH-PX和GSH作用无影响.结论:在脑缺血时间窗内,HBO治疗能增 加脑缺血区线粒体自由基生成,提高线粒体抗自由基酶活性;能抑制脑缺血半暗区线粒体的 脂质过氧化损伤,但对核心区作用不明显.提示线粒体的功能状态在HBO治疗后的自由基反应中起重要作用.

Effect of hyperbaric oxygen treatment on mitochondrial free radicals after transient focal cerebral ischemia in rats

OBJECTIVE: To investigate the effect of hyperbaric oxygen(HBO)therapy on mitochondrial free radicals after transient focal cerebral ischemia in rats. METHODS: The male SD rats were randomly assigned into two groups, control and HBO groups. All animals were subjected to 90 min intra-luminal middle cerebral artery occlusion (MCAO) with the regional cerebral blood flow monitored in vivo by laser Doppler flowmetry. HBO treatment was performed in a pressure chamber with 100% O(2)(3 ATM 1 h) 3 h after ischemia. Twenty-four hours after ischemia, mitochondria in the ischemic core and penumbra were isolated and the contents of H(2)O(2), O(2)(*-), MDA, SOD, GSH-PX and GSH in mitochondria were measured respectively. RESULT: After cerebral ischemia-reperfusion, contents of mitochondrial H(2)O(2), O(2)(*-), MDA increased, while the SOD, GSH-PX and GSH in the mitochondria decreased significantly both in the ischemic core and the ischemic penumbra, compared with those in the normal controls(P<0.05). In the ischemic penumbra, HBO therapy increased significantly the content of O(2)(*-)(P<0.05), enhanced the activity of SOD, and decreased the level of MDA (P<0.05). However, HBO therapy did not change the level of MDA, though it also increased the content of O(2)(*-) and the activity of SOD in the ischemic core. HBO therapy had no significant effect on the contents of H(2)O(2), GSH-PX and GSH in the ischemic mitochondria. CONCLUSION: HBO therapy initiated early after acute transient cerebral ischemia in rats can increase the mitochondrial free radicals level, but also increase the activity of the anti-radical enzymes. HBO treatment inhibits the lipid peroxidation damage of mitochondria in the ischemic penumbra, but not in the ischemic core, which indicates that the mitochondrial function plays a role in the reaction of the free radical in the ischemic area after HBO therapy.