Ca A/K Channel Regulation in Hippocampal Neurons

描述(由申请人提供)：该项目的总体、长期目标 目的是发现钙离子通透性AMPA/海人藻酸(Ca-A/K)通道在心肌梗死中的作用 海马区部分神经元的选择性神经退行性变 在缺血性、癫痫或创伤性脑损伤后，如果这些渠道 在一些神经退行性疾病中也很重要，如肌萎缩侧索硬化症和阿尔茨海默病。这个 AMPA通道的钙离子通透性由亚基的存在决定 GluR2，使AMPA通道对钙离子不通透。以前的研究 GluR2 mRNA和多肽下调的实验研究 脑损伤的形式表明，在某些情况下，神经元死亡可能是 由可能导致过量的新的Ca-A/K通道的形成所介导 钙或锌离子内流，失去离子稳态，最终死亡。到目前为止， 然而，还没有人直接证明 侮辱后GluR2蛋白的丢失。我们假设Ca-A/K的数目 通道在突触位置被动态调节，在那里它们最可能 可能调节了过量的离子流量，在某些形式的神经退行性变中， Ca-A/K通道数量的上调确实是由于 下调GluR2的表达。我们首先建议开发一种细胞培养系统来 应用荧光成像技术评估钙通道的存在和数量 免疫细胞化学。然后，我们将使用该系统来评估监管 功能性突触Ca-A/K通道对培养神经元的作用 模拟损伤的条件，或可能 可能改变Ca-A/K通道水平。我们还建议检验我们的假设 在体内，使用红藻氨酸诱导癫痫模型评估突触GluR2水平。

DESCRIPTION (provided by applicant): The broad, long-term goal of this project is to discover the role of Ca2+ permeable AMPA/Kainate (Ca-A/K) channels in selective neurodegeneration of a subpopulation of neurons in the hippocampus following ischemic, epileptic, or traumatic brain injury, and if these channels are also important in some neurodegenerative diseases such as ALS and AD. The Ca2+ permeability of AMPA channels is determined by the presence of the subunit GluR2, which renders AMPA channels impermeable to Ca2+. Previous studies demonstrating the down regulation of GluR2 mRNA and peptide following some forms of brain insult suggests that neuronal death in some cases may be mediated by the formation of new Ca-A/K channels that could lead to excessive Ca2+ or Zn2+ influx, loss of ionic homeostasis, and eventual death. To date, however, no one has demonstrated directly the physiological relevance of the loss of GluR2 protein following insult. We hypothesize that numbers of Ca-A/K channels are dynamically regulated at synaptic sites where they would most likely mediate excessive ion flux, and that in some forms of neurodegeneration, an upregulation in the number of Ca-A/K channels does indeed occur due to the down regulation of GluR2. We first propose to develop a cell culture system to assess presence and numbers of Ca-A/K channels using fluorescent imaging and immunocytochemistry. We will then use this system to assess regulation of functional synaptic Ca-A/K channels following treatment of cultured neurons to injury mimicking conditions, or molecular biological procedures that may potentially alter Ca-A/K channel levels. We also propose to test our hypothesis in vivo, using a kainate induced seizure model to asses synaptic GluR2 levels.