Role of L-Type Calcium Channels in Hippocampal Neuronal Network Activity

描述(由申请人提供)：自闭症谱系障碍(ASD)是一种普遍存在但知之甚少的神经疾病。蒂莫西综合征是一种与自闭症有非常重要联系的疾病，最近被证明具有单基因起源，起源于L类型钙离子通道内的单核苷酸替换。这种突变延长了通道开放的时间，这种效应可以被L类钙通道激动剂Bayk8644在药理上模拟。通过这种方式，我们可以在动物模型中总结TS，从而产生可能推广到其他ASD的发现。这种动物模型可以从分子机制到海马区回路对TS进行详细的研究。这项建议的目的是从多个水平表征bayk 8644对海马区从突触到回路的生理过程的影响，并提供一个路线图，说明单个分子故障如何影响导致疾病表型的神经回路的功能。具体目标1-检验Bayk 8644导致突触后突触激活增强的假设 钙离子激活兴奋性突触传递过程中的钾电导。我们已经证明Bayk 8644对大鼠海马片兴奋性突触传递有抑制作用。我们提出了一系列实验来描述这种令人惊讶的效应背后的细胞生理学。2.具体目标2-开发一种系统，用于研究海马片制备中的行为相关网络动力学。我们开发了一种新的系统，使用多单位四极管记录来研究急性海马片的模式分离。利用这种良好控制的切片制备，我们建议探索模式完成和模式分离之间的网络转换点。具体目标3-检验Bayk 8644通过破坏兴奋和抑制影响在回路中的平衡来干扰海马回路动力学的假设。通过在一系列类似于目标2中描述的实验中应用bayk 8644，我们建议在自闭症谱系障碍的急性模型中测试行为相关的电路动力学是如何受到影响的。我们将结合细胞内和四极管记录，以便将亚细胞与这种疾病模型的宏观效应联系起来。与公共卫生相关：自闭症谱系障碍是一种常见的、令人严重衰弱的心理障碍。虽然最近的证据暗示了这种疾病的遗传基础，但我们对如何将基因发挥作用与[最终]治疗联系在一起知之甚少。我们在这里提出了一系列实验，以加深对一个自闭症谱系障碍模型如何在从基因到分子再到神经回路的多个水平上发挥作用的理解，因为它们在大脑中发挥作用。

DESCRIPTION (provided by applicant): Autism spectrum disorder (ASD) is a pervasive but poorly understood neurological disorder. Timothy Syndrome, a disorder with a highly significant link to ASD, has recently been shown to have a monogenetic origin in a single nucleotide substitution within the L-type Ca2+ channel. This mutation prolongs channel opening, an effect that can be mimicked pharmacologically by the L-type Ca2+ channel agonist BayK 8644. In this way we can recapitulate TS in an animal model to generate findings that can potentially generalize to other ASDs. This animal model allows for a detailed investigation of TS from molecular mechanisms to hippocampal circuitry. The goal of this proposal is to characterize the effects of BayK 8644 on physiological processes in the hippocampus at multiple levels from synapses to circuits and to provide a roadmap for how a single molecular malfunction can affect the functioning of a neural circuit leading to a disease phenotype.l. Specific Aim 1 - To test the hypothesis that BayK 8644 leads to enhanced activation of a postsynaptic Ca2+-activated K+ conductances during excitatory synaptic transmission. We have demonstrated that BayK 8644 has a dampening effect on excitatory synaptic transmission in acute slices of rat hippocampus. We propose a series of experiments to characterize the cellular physiology underlying this surprising effect. II. Specific Aim 2 - To develop a system for studying behaviorally relevant network dynamics in a hippocampal slice preparation. We have developed a novel system using multi-unit tetrode recordings to study pattern separation in an acute hippocampal slice. Using this well-controlled slice preparation, we propose to probe the network transition point between pattern completion and pattern separation. III. Specific Aim 3 - To test the hypothesis that BayK 8644 interferes with hippocampal circuit dynamics by upsetting the balance of excitatory and inhibitory influences in the circuit. By applying BayK 8644 during a series of experiments similar to those described in Aim 2, we propose to test how the behaviorally relevant circuit dynamics are affected in an acute model of autism spectrum disorder. We will combine intracellular and tetrode recordings in order to connect the subcellular to the macroscopic effects of this disease model. PUBLIC HEALTH RELEVANCE: Autism spectrum disorder is a common and profoundly debilitating psychological disorder. While recent evidence has implied a genetic basis for this disease, we know very little about how to connect genes to function to [eventually] treatment. We propose here a series of experiments to develop a deeper understanding of how one model of autism spectrum disorder might function at multiple levels from genes to molecules to neural circuits as they function in the brain.