Glutamate neurotransmission in Alzheimer's disease progression

项目摘要/摘要 尽管有证据支持谷氨酸能系统参与阿尔茨海默氏症 疾病(AD)，研究集中在谷氨酸(Glu)参与的间接测量上，主要是 通过增加与兴奋性毒性相关的下游通路，而不处理可能的 在疾病进展过程中细胞外Glu的变化。基础知识和 时相细胞外谷氨酸水平和清除动力学将使我们能够建立早期的 生物标志物，更好地确定和探索新的治疗靶点，并建立时机 有可能改变AD进展的治疗窗口。直到最近，研究人员 测量细胞外Glu水平一直是有限的，因为很少有技术能够 在大脑的小区域内进行活体分析。我们已经开发出一种MEA，当 结合电化学，有能力测量微摩尔变化的基础和 具有高时间(毫秒)和空间(微米)分辨率的时相细胞外Glu 以及长期录音。我们计划使用这项技术来解决我们的核心假设 清醒动物细胞外Glu的变化发生在认知功能下降和 与AD相关的神经病理，随着年龄的增长，β的积累加强了这些 这些变化会导致阿尔茨海默病中典型的认知衰退。这一假设将使用以下方法进行评估 一种新的AD、APPNL-F/NL-F和APP/PS1小鼠敲入小鼠模型及其各自 对照组为2-4、8-10和18-20个月龄。在这些年龄段，一组小鼠将经历 使用Morris水迷宫和觉醒刺激(KCL)诱发的Glu进行认知评估 记录在海马区的CA1区。这些研究将帮助我们确定基本的 AD患者谷氨酸和谷氨酸释放(突触前)和摄取(神经胶质细胞和突触后)动力学改变 如果是这样的话，这些变化是如何以及何时在认知和 病理生理衰退。接下来，为了确定谷氨酸神经传递的变化是否 在行为上有害的，我们将检查第二组相同年龄和 在记忆相关的海马亚区任务中，自发交替的y迷宫。这 将使我们能够确定衰老和AD进展对形成和回忆的影响 以阶段性谷氨酸测量的形式的记忆。总而言之，我们预计这些 研究将使我们对谷氨酸作为早期生物标志物的作用有价值的洞察，这是一种 疾病进展，潜在的新治疗靶点和最佳干预 AD的时间范围。

Project Summary/Abstract In spite of the evidence supporting the involvement of the glutamatergic system in Alzheimer’s disease (AD), research has focused on indirect measures of glutamate (Glu) involvement, mainly through increased downstream pathways related to excitotoxicity, without addressing possible changes in extracellular Glu occurring during disease progression. Knowledge of basal and phasic extracellular Glu levels and clearance kinetics would allow us to establish an early biomarker, better determine and explore novel therapeutic targets, and establish the opportune treatment window that has the potential to alter AD progression. Until recently, research measuring extracellular Glu levels has been limited because few techniques are capable of in vivo analysis within small sub-regions of the brain. We have developed a MEA that, when combined with electrochemistry, has the ability to measure micromolar changes in basal and phasic extracellular Glu with high temporal (msec) and spatial (micron) resolution during acute and chronic recordings. We plan to use this technique to address our central hypothesis that alterations in extracellular Glu in awake animals occur prior to cognitive decline and neuropathology associated with AD, and that Aβ accumulation with age potentiates these changes resulting in the cognitive decline typical in AD. This hypothesis will be evaluated using a novel knock-in mouse model of AD, APPNL-F/NL-F mice, and APP/PS1 mice, and their respective controls at 2-4, 8-10, and 18-20 months of age. At these ages, one cohort of mice will undergo cognitive evaluation using the Morris water maze followed by awake stimulus (KCl)-evoked Glu recordings in the CA1 region of the hippocampus. These studies will help us determine if basal Glu and Glu release (presynaptic) and uptake (glia and postsynaptic) kinetics are altered in AD mice and if so, how and when these alterations occur over the continuum of cognitive and pathophysiological decline. Next, to determine if alterations in Glu neurotransmission is behaviorally detrimental, we will examine a second group of mice at the same ages and hippocampal sub-region during a memory related task, the spontaneous alternation y maze. This will allow us to determine the impact of aging and AD progression on formation and recall of memories in the form of phasic Glu measurements. Taken together, we anticipate that these studies will give us valuable insight into the role of Glu as an early biomarker, a mechanism for disease progression, a site for potential novel therapeutic targets, and optimal intervention timeframes for AD.