Effect of Physiological Changes in Neuronal Activity AB Levels in Vivo

描述（由申请人提供）：阿尔茨海默病（AD）是迟发性痴呆的主要原因，以进行性认知能力下降和记忆丧失为特征，最终导致死亡。目前有超过500万美国人患有阿尔茨海默病，每年阿尔茨海默病和其他痴呆症的总费用超过1450亿美元。因此，了解阿尔茨海默病的发病机制以最终开发有效的治疗方法是至关重要的，也是本研究计划的动机。淀粉样蛋白（AP）肽以寡聚体形式和不溶性淀粉样蛋白斑块的积累似乎在AD的发病机制中起关键作用。可溶性Ab转化为这些有毒物质是浓度依赖性的。因此，调节大脑中Ab数量的机制可能是A(3)是否聚集成有毒形式的关键决定因素。我们实验室和其他实验室的数据表明，突触活动调节脑细胞外空间（间质液- ISF）内的Ab水平。然而，ISF - Ab水平如何随着突触活动的生理改变而改变尚不清楚。因此，本提案的目的是确定生理操作改变突触活动对体内ISF - Ab水平的影响。我假设神经元活动的生理变化动态地调节Ab释放到大脑的细胞外空间。在特定目标1中，我将刺激活老鼠的胡须，以引起桶状皮层内神经元活动的急剧增加。在刺激期间，我将使用电生理记录与桶状皮质体内微透析同步测量神经元活动和ISF - Ab水平，并观察在须状刺激期间水平的变化。在Specific Aim 2中，我将通过在运动期间进行体内微透析并同时在这些大脑区域进行电生理记录来确定自愿运动对海马和初级运动皮层中ISF Ab水平和神经元活动的影响。我还将通过提取运动后的大脑，并通过Western blot检测APP衍生物的蛋白质水平，来研究运动对APP加工的影响。在Specific Aim 3中，我将通过体内微透析和海马体电生理记录来确定环境富集对ISF Ab水平和神经元活动的影响。最后，我将使用微透析来确定富集是否会改变大脑细胞外间隙的Ab清除。公共卫生相关性：该建议与公共卫生的相关性在于阐明正常生理条件下大脑中Ab水平的调节机制可能为阿尔茨海默病的发病机制提供新的见解，并可能最终为治疗干预提供新的机会。

DESCRIPTION (provided by applicant): Alzheimer's Disease (AD) is the leading cause of late-onset dementia and is characterized by progressive cognitive decline and memory loss, ultimately leading to death. Over 5 million Americans are currently suffering from AD, and the total costs of AD and other dementias exceed $145 billion annually. Understanding the pathogenesis of AD in order to ultimately develop effective treatments is therefore paramount and is the motivation for this research proposal. Accumulation of the amyloid beta (AP) peptide into oligomeric forms and insoluble amyloid plaques appears to play a critical role in AD pathogenesis. Conversion of soluble Ab into these toxic species is concentration-dependent. Thus, mechanisms that regulate the amount of Ab in the brain may act as key determinants of whether A (3will aggregate into toxic forms. Data from our laboratory and others have demonstrated that synaptic activity regulates Ab levels within the extracellular space of the brain (interstitial fluid - ISF). However, how ISF Ab levels change as a result of physiological alterations in synaptic activity is not known. Therefore, the objective of this proposal is to determine the effect of physiological manipulations that alter synaptic activity on ISF Ab levels in vivo. I hypothesize that physiological changes in neuronal activity dynamically regulate the release of Ab into the extracellular space of the brain. In Specific Aim 1,1 will stimulate the whiskers of a live mouse in order to elicit an acute increase in neuronal activity within the barrel cortex. During the stimulation period, I will use electrophysiological recording simultaneously with in vivo microdialysis in barrel cortex to measure neuronal activity and ISF Ab levels and observe how levels change during whisker stimulation. In Specific Aim 2, I will determine the effect of voluntary exercise on ISF Ab levels and neuronal activity in hippocampus and primary motor cortex by performing in vivo microdialysis with concurrent electrophysiological recording in these brain regions during exercise. I will also examine the effect of exercise on APP processing by extracting brains after exercise and measuring protein levels of APP derivatives by Western blot. In Specific Aim 3,1 will determine the effects of environmental enrichment on ISF Ab levels and neuronal activity using in vivo microdialysis and electrophysiological recording in the hippocampus following enrichment. Finally, I will use microdialysis to determine if enrichment alters Ab clearance from the extracellular space of the brain. Public Health Relevance: The relevance of this proposal to public health is that elucidating the mechanisms that regulate Ab levels in the brain under normal physiological conditions may provide novel insights into AD pathogenesis and may ultimately provide new opportunities for therapeutic intervention.