远端缺血后处理对大鼠全脑缺血再灌注损伤的影响

Effects of remote ischemic-postconditioning on global cerebral ischemia-reperfusion injury in rats

目的探讨远端缺血后处理对大鼠全脑缺血再灌注损伤的影响。方法健康成年雄性SD大鼠128只，体重为200～250g，采用随机数字表法，将其随机分为4组（n：32）：假手术组（S组）、缺血再灌注组（I／R组）、I／R＋远端缺血后处理组（I／R＋RIPoC组）以及远端缺血再灌注组（RI／R组）。采用改良的Pulsinelli四动脉阻断法建立大鼠全脑缺血再灌注模型。S组不制备全脑缺血再灌注模．型；I／R＋RIPoC组于再灌注开始行双侧股动脉缺血15min，再灌注15min，共计3个循环；RI／R组仅行双侧股动脉缺血15min，再灌注15min，共计3个循环。于再灌注24、48h时取脑组织，行海马CAl区和额叶皮层凋亡细胞计数，测定海马CAl区Bcl-2和Bax的表达水平，并于再灌注48h测定超氧化物歧化酶（SOD）和过氧化氢酶（CAT）的活性及丙二醛（MDA）的含量；再灌注4d时行Morris水迷宫实验；再灌注7d时取脑组织，计算海马CAl区和额叶皮层神经元密度。结果与S组比较，I／R组再灌注时凋亡细胞计数升高，Bcl-2和Bax表达上调，神经元密度、SOD和CAT活性降低，MDA含量升高，逃避潜伏期明显延长，穿越原平台次数与第2象限停留时间百分比降低（P〈0．01），RI／R组上述指标差异无统计学意义（P〉0．05）；与I／R组比较，I／R＋RIPoC组再灌注时凋亡细胞计数降低，Bcl-2表达上调，Bax表达下调，神经元密度、SOD和CAT活性升高，MDA含量降低，逃避潜伏期缩短，穿越原平台次数与第2象限停留时间百分比升高（P〈0．01）。结论远端缺血后处理可减轻大鼠全脑缺血再灌注损伤，其机制与抑制脂质过氧化反应，调节Bcl-2与Bax的平衡抑制细胞凋亡有关。

Objective To investigate the effects of remote ischemic postconditioning （RIPoC） on global cerebral ischemia-reperfusion （I/R） injury in rats. Methods One hundred and twenty-eight male adult SD rats weighing 200-250 g were randomly divided into 4 groups （ n = 32 each） ： sham operation group （group S）, group I/R, group I/R ＋ RIPoC and remote I/R group （group RI/R ） . Global cerebral I/R was induced by four-vessel occlusion. Group I/R ＋ RIPoC received 3 cycles of 15 min reperfusion followed by 15 rain ischemia in bilateral femoral arteries at the beginning of cerebral reperfusion. The rats were sacrificed at 24 and 48 h of cerebral reperfusion, and brains were removed for determination of neuronal apoptosis （by TUNEL method） in hippocampal CA1 region and the parietal cortex, Bcl-2 and Bax expression （by Western blot） in hippocampal CAI region. The superoxide dismutase （SOD） and catalase （CAT） activity and malondialdehyde （MDA） content in hippocampal CA1 region and the parietal cortex were also measured at 48 h of cerebral reperfusion. Morris water maze task was used to test the learning and memory function at 4 d of cerebral reperfusion, and the rats were sacrificed at 7 d of cerebral reperfusion, and brains were removed for determination of neuronal density in hippocampal CA1 region and the parietal cortex. Results Cerebral I/R significantly increased the number of apoptotic neurons and MDA content, upregulated Bcl-2 and Bax expression, decreased neuronal density, SOD and CAT activity and learning and memory function in group I/R as compared with group S. RIPoC significantly attenuated these cerebral I/R-induced changes. Conclusion RIPoC could protect brain against global cerebral I/R-induced injury, and the mechanism may be related to inhibiting lipid peroxidation, regulating the balance between Bcl-2 and Bax and inhibiting apoptosis.