阿尔茨海默病患者脑神经元存活信号转导的障碍

Impairment of signal transduction pathway on neuronal survival in brains of Alzheimer′s disease

目的 探讨阿尔茨海默病 (Alzheimer′sdisease ,AD)患者脑神经元凋亡的可能机制。方法 ( 1)免疫组织化学双染色 :①Tunel标记DNA片段的 3′ OH端 ,用硫酸镍加DAB显色 ,阳性产物呈深蓝色。②免疫组织化学标记神经元 :采用抗生物素蛋白 生物素复合物 (ABC)法 ,DAB显色 ,阳性产物呈棕黄色。 ( 2 )将死后 6h以内取材的AD患者和非AD患者脑海马组织分为两组 ,每组分别取 6例 ,匀浆后用Lowry法进行蛋白定量 ,将总蛋白量相等的样品进行免疫沉淀Western印迹分析。结果 ( 1)AD患者和非AD患者对照组脑组织切片中都存在凋亡细胞 ,但AD患者脑组织切片中单位面积凋亡细胞发生率增加。 ( 2 )AD患者海马组织Akt/PKB ,cAMP应答元件结合蛋白 (CREB) ,磷酸化的CREB表达减少 ,凋亡诱导因子表达增加 ,bcl 2表达减少 ,而bax的表达无明显差异。结论 AD患者海马存在神经元存活信号转导通路障碍 。

Objectives To explore the mechanisms of neuronal loss and apoptosis in the brains of Alzheimer′s disease (AD) patients, through studying the expression of proteins related to signal transduction pathways, which are important for neuron survival. Methods (1) Immunohistochemistry: Sections were double stained with Tunel and NSE antibodies. (2) The hippocampal tissue taken from 6 cases of AD and 6 cases of non-AD brains was homogenized. Protein estimation was done by Lowry method. Equal amounts of protein were taken from each specimen and immunoprecipitation was performed and analyzed by Western blot; color development was done by alkaline phosphatase method or luminol reagent. Results (1) Tunel positive neurons were found in both AD and non-AD brains, but the number in the former was more than the latter. (2) The AD hippocampal tissue showed diminished expression of Akt/PKB, CREB, P-CREB, increased expression of apoptosis-related protein apoptosis-inducing factor, and diminished expression of apoptosis-related protein bcl-2. The expression of bax did not change. Conclusions Diminished expression of CREB, P-CREB, bcl-2 in AD hippocampus indicates that the neuron survival signal transduction pathway in AD brains is impaired. Neurons are in apoptotic or pro-apoptotic state. In addition, increased expression of apoptosis-inducing factor, diminished expression of bcl-2, which is an anti-apoptotic factor, promotes further neuron apoptosis.