TEMPORAL RELATIONSHIP BETWEEN SYNAPTIC ACTIVITY AND ABETA AGGREGATION

描述（由申请人提供）：大脑中A¿斑块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，斑块存在于大脑中表现出高水平神经元活动的区域，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岁时就在受影响的区域出现斑块。我们实验室的研究表明，突触活动的直接调节动态调节清醒动物的脑A¿水平，突触活动的增加迅速增加脑间质液（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。确定这种联系背后的机制对于理解AD的病理发展仍然很重要。我们开发了新型微免疫电极（MIEs），以非常高的时间分辨率检测A¿（每分钟测量体内A¿）。这种方法使我们能够研究A¿在体内的快速动力学和动力学。在我们发表的研究（Prabhulkar et al. 2012）和初步数据中，我们表明这些密斯可以根据附着在电极表面的抗体特异性地测量ISF A¿1-40、A¿1-42或聚集体。我们的体内MIE研究证实了脑间质液（ISF） A¿水平

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.