缺氧预处理对缺氧缺血性脑损伤新生大鼠神经干细胞增殖的影响

目的探讨缺氧预处理（HPC）对缺氧缺血性脑损伤（HIBD）新生大鼠神经干细胞增殖的影响，为HPC的保护机制提供依据。方法48只7d龄新生SD大鼠，随机分成4组：缺氧缺血组、HPC＋缺氧缺血组、假手术组、正常对照组，每组12只。缺氧缺血组在当天先行左侧颈总动脉结扎术，然后放入缺氧装置吸入8％氧气和92％氮气的混合气体2．5h，建立HIBD动物模型。HPC＋缺氧缺血组在术前1d先行HPC，即将大鼠放人密闭容器中通人8％氧气和92％氮气混合气体3h，第二天再依次同法建立HIBD动物模型。假手术组仅分离左侧颈总动脉，不结扎，也不做HPC。正常对照组未做任何处理。在建立动物模型后48h将全部动物同时处死。对各组新生大鼠脑皮质、室管膜下区、海马区的神经干细胞增殖的标记物一巢蛋白（nestin）的表达进行观察。结果HPC＋缺氧缺血组在皮质、室管膜下区、海马区nestin阳性细胞数量明显多于其他3组（P〈0．01或P〈0．05），缺氧缺血组nestin阳性细胞数量也多于对照组与假手术组（P均〈0．05），对照组nestin阳性细胞数量与假手术组比较无统计学差异（P〉0．05）。结论HPC对HIBD具有保护作用，可增加HIBD新生大鼠神经于细胞的增殖，以增加脑损伤的康复能力。

Effect of hypoxia preconditioning on nervous stem cells proliferation in newborn rats with hypoxic-ischemic brain damage

Objective To investigate the effect of hypoxia preconditioning （HPC） on nervous stem cells proliferation in newborn rats with hypoxic-ischemic brain damage （HIBD）. Methods A total of 48 7-day old SD rats were randomly divided into 4 groups （n = 12 each）： hypoxic-ischemia group, HPC plus hypoxic-ischemia group, sham operation group, and normal control group. In hypoxic-ischemia group, the left common carotid artery ligation was performed first, and then the rats were put into a sealed container containing mixed gas consisting of 8 percent of oxygen and 92 percent of nitrogen for 2.5 h to establish HIBD model. In HPC plus hypoxic-ischemia group, HPC （putting the rats into a sealed container containing mixed gas consisting of 8 percent of oxygen and 92 percent of nitrogen for 3 h） was performed the day before operation, and then the HIBD model was established with the same way at the second day. In sham operation group, neither ligation nor HPC was performed besides separating the left common carotid artery. In normal control group, any treatment was not given. All of the rats were simultaneously killed 48 h after molding. The expressions of nestin, a marker of nervous stem cells proliferation, on cerebral cortex, subventrieular zone and hippocampus were observed in all groups. Results Tile numbers of nestin positive ceils in cerebral cortex, subventricular zone and hippocampus in the HPC plus hypoxic-ischemia group were more than those in the other three groups （ P 〈 O. 05 or P 〈 0.01 ）, and the numbers of nestin positive cells in hypoxic-ischemia group were also more than those in sham operation group and normal control group （ all P 〈 0.05 ）. There was no significant difference in the numbers of nestin positive cells between sham operation group and normal control group （P 〉 0.05）. Conclusions HPC has a protective effect against HIBD. It can promote the proliferation of nervous stem cells in order to enhance the rehabilitation ability of brain damage.