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目的探讨脑缺血再灌注(ischemia/reperfusion,I/R)致神经元退行性变自由基和SOD-1表达的时程变化。方法 NIH小鼠160只,分为I/R组和假手术组,每组80只。抽取并回输约40%总血量加双侧颈总动脉夹闭20 min建立I/R损伤模型。分别于术后5、15、30、60 d以光学显微镜观察神经元损伤;Morris水迷宫评价学习记忆能力;分光光度计法检测SOD-1活性和丙二醛(MDA)含量;RT-PCR和Western blot分别检测海马SOD-1 mRNA和蛋白表达。结果假手术组脑组织MDA含量、SOD-1活性及蛋白、mRNA表达分别为(0.549±0.049)nmol/mg、(55.134±4.076)U/mg、30.413±2.962和104.541±18.825。与假手术组比较,I/R组小鼠学习记忆能力显著降低,术后5、15、30、60 d脑组织MDA含量[(0.673±0.087)、(0.782±0.101)、(0.719±0.094)、(1.084±0.140)nmol/mg]进行性显著升高(P<0.05);术后5 d和15 d I/R组SOD-1活性[(42.522±3.701)、(37.011±4.843)U/mg]和蛋白表达(23.145±3.476、15.746±2.344)显著降低(P<0.05);术后30 d和60 d I/R组SOD-1活性[(51.801±6.706)、(50.202±6.488)U/mg]与假手术组间差异无显著性(P>0.05),但SOD-1蛋白表达(40.587±6.154、44.263±6.597)较假手术组显著升高(P<0.05);各组SOD-1 mRNA表达水平无显著差异(P>0.05);组织学检测显示I/R组海马出现进行性神经元核固缩加重和神经元丢失。结论 I/R致小鼠神经元退行性变与SOD-1表达和功能异常和氧化应激进行性增强有关。
Objective To investigate the time-course changes of the expression of neuron degeneration and SOD-1 in cerebral ischemia-reperfusion (I / R) rats. Methods 160 NIH mice were divided into I / R group and sham operation group, 80 rats in each group. I / R injury model was established by withdrawing and returning about 40% of the total blood volume and bilateral common carotid artery occlusion for 20 min. Neuronal damage was observed by light microscope at 5, 15, 30 and 60 days after operation respectively. Morris water maze was used to evaluate learning and memory ability. SOD-1 activity and MDA content were detected by spectrophotometer. RT- Western blot was used to detect the expression of SOD-1 mRNA and protein in hippocampus. Results The content of MDA, the activity of SOD-1 and the protein and mRNA expressions of brain tissue in sham operation group were (0.549 ± 0.049) nmol / mg, (55.134 ± 4.076) U / mg, 30.413 ± 2.962 and 104.541 ± 18.825, respectively. Compared with the sham operation group, the learning and memory abilities of I / R mice decreased significantly (P <0.01) (P <0.05). The activity of SOD-1 in I / R group on the 5th and 15th day after operation [(42.522 ± 3.701), (37.011 ± 4.843) U / (P <0.05). The activity of SOD-1 in the I / R group after 30 d and 60 d [(51.801 ± 6.706), (50.202 ± 6.488) U (P <0.05). However, the expression of SOD-1 protein in the three groups was significantly higher than that in the sham operation group (40.587 ± 6.154, 44.263 ± 6.597, P <0.05) 1 mRNA in hippocampus of I / R group showed no significant difference (P> 0.05). Histological examination showed progressive neuron pyknosis and neuronal loss in hippocampus of I / R group. Conclusion I / R-induced degeneration of neurons in mice is related to the abnormal expression of SOD-1 and the dysfunction of neurons and the progressive enhancement of oxidative stress.