TEMPORAL RELATIONSHIP BETWEEN SYNAPTIC ACTIVITY AND ABETA AGGREGATION

描述(由申请人提供)：A？斑块在大脑中的积累是阿尔茨海默病的一个显著特征，也是疾病进展的生物标记物。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，约10%的颞叶癫痫患者早在30岁时就会在受累区域内形成斑块。我们实验室的研究表明，对突触活动的直接调节可以动态地调节清醒动物的脑A？水平，突触活动增加会迅速增加脑间质液(ISF)A？水平，反之亦然。这些发现有力地表明，突触活动和A？的产生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(Mies)，可以检测到非常高的时间分辨率(每分钟在体内测量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。在我们发表的研究中(Prabbulkar等人)。2012)，在初步数据中，我们表明这些MIE可以根据电极表面附着的抗体而特异性地测量ISF A？1-40、A？1-42或聚集体。我们的体内MIE研究表明脑间质液(ISF)A？水平 在APP/PS1转基因小鼠中，每分钟都会发生变化。我们小组和其他人以前发表的文章表明，ISF A？水平与突触传递密切相关。体外实验数据表明，高浓度和低pH有利于A？转化为有毒的聚集体。突触活动增加了内小体中A？的生成，这是一个pH低的受限位置，A？的浓度可能会升高。我们认为，突触传递和A？生成之间存在快速联系，突触传递的频率越高，就会形成更多的A？此外，在低pH值的内体中，突触A？的生成增加会将A？转化为聚集态(寡聚体或纤维)。这项建议的目的是利用这项新的MIE技术结合药物操纵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。这些研究的结果将有助于我们更好地理解突触活动与A？代/种之间的时间关系，并揭示AD进展的机制。

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.