Beckstrøm H, Julsrud L, Haugeto O, Dewar D, Graham D I, Lehre K P, Storm-Mathisen J, Danbolt N C
Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, Norway.
J Neurosci Res. 1999 Jan 15;55(2):218-29. doi: 10.1002/(SICI)1097-4547(19990115)55:2<218::AID-JNR9>3.0.CO;2-L.
Alzheimer's disease is a common progressive neurodegenerative disease of unknown etiology. Several different pathological processes have been identified in the brains of Alzheimer patients. To determine if reduced glutamate uptake is a contributing factor, we have measured the levels of the glutamate transporter proteins GLAST (EAAT1) and GLT (EAAT2) in human autopsy samples. The postmortem proteolysis of these proteins turned out to be fairly rapid. Brains from 10 Alzheimer and 10 control patients were therefore obtained with a relatively short postmortem delay (5 hr on average). GLT (N-terminal and central parts), GLAST (C-terminal), glial fibrillary acidic protein (GFAP) and inositol (1,4,5)-triphosphate (IP3)-receptor immunoreactivities were determined in the cingulate and inferior temporal gyri by immunoblotting. The Na+-dependent "binding" of D-[3H]aspartate and the glutamate uptake after solubilization and reconstitution in liposomes were determined for comparison. An individual variation in GLAST and GLT levels was found, but no significant correlation with Alzheimer's disease, except for a 14% lower ratio of N-terminal to central GLT immunoreactivity (P < 0.04). The levels of GLAST and GLT showed negative correlation in agreement with the idea that these proteins are differentially regulated. In conclusion, Alzheimer's disease brains can have both normal and reduced levels of GLAST and GLT.
阿尔茨海默病是一种病因不明的常见进行性神经退行性疾病。在阿尔茨海默病患者的大脑中已发现几种不同的病理过程。为了确定谷氨酸摄取减少是否是一个促成因素，我们测量了人类尸检样本中谷氨酸转运蛋白GLAST（EAAT1）和GLT（EAAT2）的水平。结果发现这些蛋白质的死后蛋白水解相当迅速。因此，从10例阿尔茨海默病患者和10例对照患者的大脑中获取样本，尸检延迟相对较短（平均5小时）。通过免疫印迹法测定扣带回和颞下回中GLT（N端和中央部分）、GLAST（C端）、胶质纤维酸性蛋白（GFAP）和肌醇（1,4,5）-三磷酸（IP3）受体的免疫反应性。为作比较，还测定了D-[3H]天冬氨酸的钠依赖性“结合”以及脂质体溶解和重构后的谷氨酸摄取。发现GLAST和GLT水平存在个体差异，但除了N端与中央GLT免疫反应性的比率低14%（P<0.04）外，与阿尔茨海默病无显著相关性。GLAST和GLT的水平呈负相关，这与这些蛋白质受到不同调节的观点一致。总之，阿尔茨海默病患者大脑中GLAST和GLT的水平可能正常，也可能降低。
