【作者】 苏静；

【导师】 姜长斌；

【作者基本信息】 大连医科大学 ， 神经病学， 2009， 硕士

【摘要】 目的:研究脑缺血预处理对再次脑缺血的神经功能、细胞形态、线粒体通透性转换(mitochondrial permeability transition,MPT)及细胞色素C(cytochrome c,CytC)水平的影响,进一步探讨脑缺血预处理的脑保护机制。方法:48只雄性SD大鼠(体重230-300g)随机分成4组:假手术组(n=12)、单纯预处理组(n=12)、脑缺血组(n=12)、预处理后脑缺血组(n=12)。假手术组:颈部正中切口暴露右侧颈总动脉后缝合皮肤。单纯预处理组:按Longa线栓法略加改进制成局灶-局灶脑缺血模型,缺血30分钟,拔出线栓之后结扎颈外动脉残端。脑缺血组:线栓直接栓至右侧大脑中动脉,缺血时间为24小时。预处理后脑缺血组:预处理同单纯预处理组,术后饲养24h后在右侧颈总动脉剪一小口,经颈内动脉插入备好的线栓至右侧大脑前动脉,再缺血时间为24h小时。分别观察三组动物的以下指标:按Bederson6级5分法进行神经功能评价(每组12只);HE染色(每组12只);用免疫组织化学方法检测大鼠海马组织细胞色素C水平变化(每组12只);紫外分光光度法测定线粒体通透性转换(每组12只)。结果:(1)神经功能评分:假手术组、单纯预处理组、脑缺血组及预处理后脑缺血组神经功能评分为0,25±0.20,2.24±0.87、1.16±0.71,(n=12);假手术组与单纯预处理组比较无显著性差异(p>0.05),预处理后脑缺血组神经功能评分低于脑缺血组(p<0.05)。(2)假手术组、单纯预处理组、脑缺血组及预处理后脑缺血组海马CA1区组织切片镜下计数神经元细胞总数分别为167、161、124、138,各组的损伤神经元计数分别为13.22±4.21,13.2±7.4、90.07±10.51、61.41±8.64;假手术组与单纯预处理组海马CA1区计数神经元细胞总数及损伤数比较p>0.05,无统计学差异;预处理后脑缺血组与脑缺血组比较p<0.05,存在显著性差异。(3)细胞色素C水平测定:假手术组、单纯预处理组、脑缺血组及预处理后脑缺血组细胞色素C阳性细胞率(%)分别为10. 2±2.67, 12.5±3.9, 54.6±6.98、31.4±4.1;假手术组与单纯预处理组比较无显著性差异(p>0.05),预处理后脑缺血组细胞色素C阳性表达率低于脑缺血组(p<0.05)。(4)线粒体通透性转换检测:假手术组、单纯预处理组、脑缺血组、预处理后脑缺血组MPT的D540处OD值分别为0.568±0.083、0.547±0.098、0.298±0.077、0.427±0.113;假手术组与单纯预处理组比较无显著差别(p> 0.05),预处理后脑缺血组OD值高于脑缺血组(p<0.05)。结论:预处理后脑缺血组神经功能好于脑缺血组,细胞色素C阳性表达率低于脑缺血组, MPT的OD值高于脑缺血组,提示缺血预处理后的脑组织耐受性明显增强,对再次缺血产生脑保护作用。且MPT变化时CytC阳性表达增加,间接提示CytC从线粒体途径释放,脑缺血预处理可能是通过减轻线粒体通透性转换,从而减少CytC释放达到缺血耐受效应。更多还原

【Abstract】 Objective: To investigate the effect of ischemic preconditioning on neural function, mitochondrial permeability transition and level of cyto- chrome C in the hippocampal tissue, in order to study further the brain protection mechanism produced by ischemic preconditioning.Methods: 48 male SD rats (weight 230-300g) were randomly divided into 4 groups: false operation group(n=12), ischemic preconditioning group(n=12), ischemia group(n=12), ischemia after ischemic precondition- ing group (n=12). False operation group: sew up the skin after exposing the common carotid artery (CCA) in right. Ischemic preconditioning group: a focal-focal cerebral ischemia model was induced by adopting the thread embolism method according to Longa with a little alteration. After blocking MCA blood flow for 30 minutes, the thread was pulled out, and the ECA nub was ligated.Ischemia group: a thread was directly inserted to MCA in the right side for 24 hours. Ischemia after ischemic preconditioning group: the procedure is similar to ischemic preconditioning , then 24 hours later, a thread was inserted to ACA in the right side through CCA in 24 hours. Ischemia group: a thread was inserted to MCA in the right side by a 24 hour brain ischemia.The following parameters were observed respectively in four groups: neural function according to Bederson method, HE dying , expression of cytochrome C in the hippocampus and mitochondrial permeability transition (n=12 in each group).Results: The score of neural function was 0,0.25±0.20,2.24± 0.87,1.16±0.71 in false operation group,ischemic preconditioning group,ischemia group and Ischemia after ischemic preconditioning group respectively, and the difference was significant between ischemia after ischemic preconditioning group and ischemia group(p<0.05).The level of CytC expression was 10.2±2.67,12.5±3.9, 54.6±6.98 and 31.4±4.1 in four groups respectively, also, the difference was significant between Is- chemia after ischemic preconditioning group and ischemia group(p<0.05).The OD value of MPT was 0.568±0.083,0.547±0.098,0.298±0.077,0.427±0.113 in four groups respectively, the difference was significant between Ischemia after ischemic preconditioning group and ischemia group (p<0.05), but there was no significant difference between false operation group and ischemic preconditioning group(p>0.05).Conclusion:Our study shows that after schemic preconditioning, the score of neural function was better,the level of CytC expression was lower,the OD value of MPT was higher in the Ischemia after ischemic preconditioning group than those in the ischemia group. These indicate that ischemic preconditioning can obviously increase the tolerance to later severe ischemia injury. BIT may be derived by decreasing the MPT and declining the discharge of CytC.更多还原