缺血后适应对树鼩海马CA1区神经元Akt信号转导调控的机制研究  

Effects of ischemic postconditioning on neuronal Akt signaling pathways in hippocampus CA1 area after cerebral ischemia in tree shrews

作　　者：汤諹[1] 李树清[2] 李凡[2] 李飞[2] 张颖[2] 

机构地区：[1]昆明医学院第一附属医院皮肤/医学美容科,云南昆明650032 [2]昆明医学院基础医学院病理生理教研室,云南昆明650031

出　　处：《中国病理生理杂志》2011年第3期560-565,共6页Chinese Journal of Pathophysiology

基　　金：国家自然科学基金资助项目(No.30660056No.30971171);昆明医学院第一附属医院院内基金资助项目(No.2009BS09)

摘　　要：目的:了解缺血后适应(PC)对树鼩脑缺血时海马CA1区神经元磷脂酰肌醇-3激酶/Akt(PI-3K/Akt)下游底物丝/苏氨酸蛋白激酶(Akt Ser-473/Thr-308)磷酸化(Akt[pS473]/Akt[pT308])的调控,探讨Akt信号转导通路在缺血PC脑保护中的作用机制。方法:以树鼩为实验动物,用光化学诱导法复制局部脑缺血,并于脑缺血后3 h 30 min反复夹闭缺血侧颈总动脉3个循环(5 min 1个循环)以制备后适应模型。在光镜、电镜下观察海马CA1区神经元损伤及其超微结构变化的同时,采用免疫组化法了解脑缺血树鼩海马CA1区神经元Akt[pS473]/Akt[pT308]的分布及定位,并以灰度值检测磷酸化强度。结果:脑缺血可导致树鼩海马损伤及细胞超微结构的明显异常;而缺血PC可使海马CA1区神经元超微结构的异常明显改善。免疫组化结果显示,对照组海马CA1区Akt[pS473]及Akt[pT308]的磷酸化为阴性。缺血PC组与缺血组在不同时点的胞浆、胞膜均出现Akt[pS473],但缺血72h Akt[pS473]减弱(灰度值146.6±2.9)。缺血组Akt[pT308]仅在4 h明显增强(灰度值135.5±2.2),随后则未检测到(灰度值分别为165.3±3.7,163.3±2.5)。而缺血PC组4 h时点Akt[pT308]呈阴性,随后24 h、72 h则持续显著的阳性。结论:缺血PC能明显减轻海马CA1区神经元的缺血性损伤,其保护机制可能与Akt Ser-473和Thr-308 2个位点磷酸化导致PI-3K/Akt信号转导途径的激活有关。AIM： To investigate the phosphatidylinositol 3-kinase/Akt（PI-3K/Akt） Ser-473/Thr-308/ phosphorylation（Akt/Akt） and the intensity of the neurons in happocampus CA1 area under the conditions of thrombotic cerebral ischemia and postconditioning in tree shrews.METHODS： The thrombotic focal cerebral ischemia was induced by photochemical reaction in tree shrews.Two hundred and ten minutes after cerebral ischemia,ischemic postconditioning was established by repeated cliping of ipsilateral carotid.The distribution of Akt and Akt,and neuronal ultrastructure in hippocampus CA1 area were observed by the methods of electronic microscopy and immunohistochemistry.The phosphorylation intensity was measured by determining the optical gray value.RESULTS： The photochemical reaction induced cerebral ischemia and resulted in obvious lesions in hippocampus CA1 neurons.The damages of ultrastructure in the hippocampus were diminished by postconditioning.Correspondingly,in ischemia group,although the Akt showed positive during 72 h,the positive Akt was only observed at the time point of 4 h,and went negative at the time points of 24 h and 72 h.In postconditioning group,Akt at the time points of 4 h,24 h and 72 h were positive,and Akt at the time points of 24 h and 72 h was also positive.CONCLUSION： Cerebral ischemia leads to neuron lesions in tree shrew hippocampus and the postconditioning decreases the damage.The Akt and Akt may play important roles in the protective mechanism.

关 键 词：脑缺血 缺血后适应 磷脂酰肌醇-3激酶/Akt 信号转导 树鼩 

分 类 号：R363[医药卫生—病理学]