Effect of Physiological Changes in Neuronal Activity AB Levels in Vivo

描述(申请人提供)：阿尔茨海默病(AD)是迟发性痴呆的主要原因，其特征是进行性认知能力下降和记忆力丧失，最终导致死亡。目前有500多万美国人患有阿尔茨海默病，AD和其他痴呆症每年的总成本超过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，也是本研究提案的动机。淀粉样β蛋白(AP)多肽以低聚形式和不溶性淀粉样斑块的积聚在AD发病机制中起关键作用。可溶性抗体向这些有毒物种的转化是浓度依赖的。因此，调节大脑中抗体含量的机制可能是A(3)是否聚集成有毒形式的关键决定因素。来自我们实验室和其他实验室的数据已经证明，突触活动调节大脑细胞外空间(间质液-ISF)中的抗体水平。然而，由于突触活动的生理变化，ISF抗体水平如何变化尚不清楚。因此，这项建议的目的是确定在活体内改变突触活性的生理操作对ISF抗体水平的影响。我假设，神经元活动的生理变化动态地调节抗体的释放到大脑的细胞外空间。在特定的目标中，1，1将刺激活着的小鼠的胡须，以引起桶状皮质内神经元活动的急剧增加。在刺激期间，我将同时使用电生理记录和在体桶状皮质微透析来测量神经元活动和ISF抗体水平，并观察胡须刺激过程中水平的变化。在具体目标2中，我将通过在运动过程中对这些脑区进行微透析和同步电生理记录来确定自愿运动对这些脑区ISF抗体水平和神经元活动的影响。我还将通过提取运动后的大脑，并通过蛋白质印迹法测量APP衍生品的蛋白质水平，来研究运动对APP处理的影响。在特定的目标3，1将确定环境浓缩对ISF抗体水平和神经元活动的影响，使用体内微透析和电生理记录在海马区浓缩后。最后，我将使用微透析来确定浓缩是否改变了抗体从脑细胞外空间的清除。公共卫生相关性：这项建议与公共健康的相关性在于，阐明在正常生理条件下调节大脑中抗体水平的机制可能为AD的发病机制提供新的见解，并最终可能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.