TEMPORAL RELATIONSHIP BETWEEN SYNAPTIC ACTIVITY AND ABETA AGGREGATION

描述（由申请人提供）：A斑块在脑中的积累是阿尔茨海默病的标志性特征，也是疾病进展的生物标志物。对人类的观察表明，在大脑中显示高水平神经元活动的区域发现了斑块，有时被称为默认模式网络。同样，大约10%的颞叶癫痫患者早在30岁时就会在受影响的区域内形成斑块。我们实验室的研究表明，直接调节突触活动动态调节清醒动物的大脑A水平，增加突触活动迅速增加脑间质液（ISF）A水平，反之亦然。这些发现有力地表明突触活动和A？生成之间存在密切的时间关系。确定这种联系的机制对于理解AD的病理发展仍然很重要。我们已经开发了新型的微免疫电极（MIE），以非常高的时间分辨率检测A？（每分钟在体内测量A？）。这种方法使我们能够研究体内A？的快速动力学和动力学。在我们发表的研究（Prabhulkar等人，2012）和初步数据中，我们表明这些MIE可以特异性测量ISF A 1-40、A 1-42或聚集体，这取决于附着在电极表面的抗体。我们的体内MIE研究证明了脑间质液（ISF）A？水平 APP/PS1转基因小鼠中每分钟的变化。我们小组和其他人以前的出版物表明，ISF A？水平与突触传递密切相关。体外数据表明，高浓度和低pH值有利于A？转化为有毒聚集体。突触活动增加A？内体内的生成，pH值低的受限位置，以及A？的浓度可能会升高。我们提出，突触传递和A <$生成之间存在快速联系，更高频率的突触传递导致形成更多的A <$。此外，在低pH值内体中升高的突触A？生成将A？转化为聚集的物质（寡聚体或原纤维）。该提案的目标是使用这种新的MIE技术结合药理学操作来阻断或增强突触活动的特定方面，以阐明在短时间尺度上调节A？生成和聚集的细胞机制。这些研究的结果将提高我们对突触活动和A？代/物种之间的时间关系的理解，并揭示AD进展中涉及的机制。

DESCRIPTION (provided by applicant): Accumulation of A¿ plaque in the brain is a hallmark feature of Alzheimer's disease and a biomarker of disease progression. Observations in humans show that plaques are found in regions of the brain that display high levels of neuronal activity, sometimes referred to as the default mode network. Similarly, about 10% of individuals with temporal lobe epilepsy develop plaques within affected areas as early as 30 years of age. Studies from our lab have demonstrated that direct modulation of synaptic activity dynamically regulates brain A¿ levels in awake animals, with increased synaptic activity rapidly increases brain interstitial fluid (ISF) A¿ levels and vice versa for suppressed activity. These findings strongly suggest a close temporal relationship between synaptic activity and A¿ generation. Determining the mechanisms that underlie this link remains important for understanding the pathological development of AD. We have developed novel micro- immunoelectrode electrodes (MIEs) that detect A¿ with very high temporal resolution (measures A¿ in vivo every minute). This approach enables us to study the rapid kinetics and dynamics of A¿ in vivo. In our published studies (Prabhulkar et al. 2012), and in preliminary data we show that these MIEs can specifically measure ISF A¿1-40, A¿1-42 or aggregates, depending on the antibody attached to the electrode surface. Our in vivo MIE studies demonstrate brain interstitial fluid (ISF) A¿ levels change from minute-to-minute in APP/PS1 transgenic mice. Previous publications from our group and others demonstrate that ISF A¿ levels are closely linked to synaptic transmission. In vitro data suggest that high concentration and low pH facilitate conversion of A¿ into toxic aggregates. Synaptic activity increases A¿ generation within endosomes, a confined location where the pH is low, and the concentration of A¿ can potentially be elevated. We propose that there is a rapid link between synaptic transmission and A¿ generation, with higher frequencies of synaptic transmission causing more A¿ to be formed. In addition, elevated synaptic A¿ generation in low-pH endosomes will convert A¿ into aggregated species (either oligomers or fibrils). The goal of this proposal is to use this new MIE technology in combination with pharmacological manipulation to block or enhance specific aspects of synaptic activity to elucidate the cellular mechanisms that regulate A¿ generation and aggregation on a short time-scale. The results of these studies will improve our understanding of the temporal relationship between synaptic activity and A¿ generation/species and uncover mechanisms involved in the progression of AD.