脑部亚低温对复苏后脑的保护作用

目的：观察犬电击致室颤心脏停跳（ＶＦＣＡ）８分钟复苏后脑亚低温（３３℃）对脑脊液（ＣＳＦ）、脑组织中超氧化物歧化酶（ＳＯＤ）活力、丙二醛（ＭＤＡ）含量和脑皮质神经元超微结构的影响。方法：对犬行ＶＦＣＡ８分钟，开胸心肺复苏后观察４小时。１０只犬分为２组：正常脑温心肺复苏组（ＮＴ组，ｎ＝４）维持硬脑膜外温度３６～３７℃；选择性脑亚低温心肺复苏组（ＳＢＣ组，ｎ＝６）采用右侧颈总动脉灌注自体血冷却辅以头部表面降温维持硬脑膜外温度３３℃左右。结果：ＮＴ组复跳后各时点ＣＳＦ中ＳＯＤ活性较ＣＡ前均明显降低（Ｐ均＜０．０５），ＭＤＡ含量则均明显升高（Ｐ均＜０．０５），神经元核膜、线粒体、内质网等结构严重受损；ＳＢＣ组与ＮＴ组相比则复跳后各时点ＣＳＦ和脑组织中ＳＯＤ活性均明显升高（Ｐ均＜０．０５），ＭＤＡ含量均明显降低（Ｐ均＜０．０５），神经元超微结构损害明显减轻。结论：脑亚低温（３３℃左右）可能通过抑制脑内脂质过氧化反应和内源性氧自由基清除剂的消耗，对脑复苏起到有利的保护作用。

Effect of acupuncture plus mild hypothermia on MAPK/ERK pathway of brain tissues in rats with cerebral ischemia-reperfusion injury

Objective： To observe the protective effect of acupuncture plus mild hypothermia on brain tissues in rats with cerebral ischemia-reperfusion injury （CIRI）, and the influence on protein expression levels of phosphorylated Raf-1, MEK-2 and ERK3/2 in the mitogen-activated protein kinase （MAPK）/extracellular regulated protein kinases （ERK） pathway, and to explore the mechanism of acupuncture plus mild hypothermia therapy for the ischemic stroke. Methods： Ninety Sprague-Dawley （SD） rats were randomly divided into a blank control group, a sham operation group, a model group, an acupuncture group, a mild hypothermia group and an acupuncture plus mild hypothermia group, 15 rats in each group. Except the rats in the blank control group, the remaining rats were used to prepare the middle cerebral artery occlusion （MCAO） models according to the modified occlusion method using lines, while only the occlusion lines were inserted without blocking the brain arteries of rats in the sham operation group. When the vital signs of rats were stable, rats in the blank control group did not receive any intervention; rats in the sham operation group and the model group received fastening without treatment; rats in the acupuncture group, the mild hypothermia group, and the acupuncture plus mild hypothermia group were treated with the corresponding therapeutic methods. 72 h later, observed neurologic injury score, evaluated infarction area ratio by 2,3,5-tripheyl tetrazolium chloride （TTC） staining, determined apoptosis by TUNEL assay, and measured the phosphorylated Raf-1, MEK-2 and ERK3/2 protein expression levels in rat ischemic hippocampal tissues by Western blot assay. Results： Compared with the blank control group and the sham operation group, after modeling, the neurologic injury score, infarction area ratio and apoptotic cells were increased, and phosphorylated Raf-1, MEK-2 and ERK：1/2 protein expression levels were significantly increased in the model group; the differences were statistically significant （P〈0.05 or P〈0.01）. Compared with the model group, after acupuncture or mild hypothermia therapy, neurologic injury score and infarction area ratio were decreased; apoptotic cells and phosphowlated Raf-1, MEK-2 and ERK1/2 protein expression levels were significantly decreased; the differences were statistically significant （P〈0.05 or P〈0.01）. Compared with the acupuncture group, neurologic injury score and phosphorylated Raf-1, MEK-2 and ERK3/2 protein expression levels were decreased in the acupuncture plus mild hypothermia group; differences between the groups were statistically significant （P〈0.05 or P〈0.01）. Compared with the mild hypothermia group, phosphorylated Raf-1, MEK-2 and ERK1/2 protein expression levels decreased in the acupuncture plus mild hypothermia group, and differences were statistically significant （P〈0.01）. Conclusion： Acupuncture or mild hypothermia therapy can improve neurologic injury, reduce infarction area and apoptosis, which brought about protective effect on the brain tissues, in the MCAO model. The protective effect of acupuncture plus mild hypothermia group is the strongest. The mechanism may involve the MAPK/ERK pathway, by reducing the phosphorylated Raf-l, MEK-2 and ERK：1/2 protein expression levels.