Astrocyte volume-regulated control of neuronal excitability

星形胶质细胞体积调节神经元兴奋性

基本信息

批准号：
8481257
负责人：
DEVIN K BINDER
金额：
$ 41.63万
依托单位：
UNIVERSITY OF CALIFORNIA RIVERSIDE
依托单位国家：
美国
项目类别：
财政年份：
2013
资助国家：
美国
起止时间：
2013-06-05 至 2018-05-31
项目状态：
已结题

项目摘要

DESCRIPTION (provided by applicant): Numerous lines of evidence suggest that astrocytes actively participate in regulating neuronal excitability, but the role of astrocyte swelling in conrol of neuronal excitability has never been directly tested. Our long-term goal is to identify and understand astrocytic mechanisms controlling neuronal excitability. The objective in this particular application is to determine how specific manipulations of astrocyte swelling and swelling-evoked glutamate release lead to changes in neuronal excitability in situ and in vivo. The central hypothesis is that astrocyte swelling and glutamate release from astrocytic volume-regulated anion channels (VRAC) is both necessary and sufficient to elevate neuronal excitability in situ and in vivo. The rationale for the proposed research is that, identification o novel astrocytic pathways controlling neuronal excitability will provide new astrocytic drug targets for the treatment of neurological disorders and neurodegenerative disease. Guided by strong preliminary data, the central hypothesis will be tested by pursuing three specific aims: 1) Determine the extent to which astrocyte swelling-evoked glutamate release is necessary to increase neuronal excitability in situ; 2) Determine the extent to which astrocyte swelling-evoked glutamate release is sufficient to increase neuronal excitability in situ; and 3) Determine the contribution of astrocyte swelling to the control of neuronal excitability in vivo. Astrocyte swellng and glutamate release will be selectively manipulated using patch clamp and transgenic approaches, together with real-time imaging of astrocyte volume changes during recording of NMDA receptor activity in CA1 pyramidal neurons in acute hippocampal slices (Aims 1 and 2), and the effects of hypoosmolarity, hyperosmolarity and selective inhibitors on astrocytic volume changes and neuronal excitability will be assayed in vivo (Aim 3). Our approach is innovative, in our opinion, because it represents a significant departure from the status quo of assessing the role of astrocyte Ca2+-dependent gliotransmission in regulating neuronal excitability, and because techniques have been developed and proven feasible in our hands to selectively and specifically manipulate astrocyte volume changes and release of glutamate. The proposed re- search is significant, because once astrocytic mechanisms controlling neuronal excitability become clarified, novel astrocyte-directed therapies can be devised to prevent excessive levels of neuronal excitability while leaving basal levels of neuronal excitability and normal cognitive function intact. Such knowledge will also pro- vide new strategies to treat neurological disorders associated with cellular volume changes (including various forms of edema), while also fundamentally advancing our understanding of glial-neuronal interactions.

描述（由申请人提供）：大量证据表明星形胶质细胞积极参与调节神经元兴奋性，但星形胶质细胞肿胀在控制神经元兴奋性中的作用从未被直接测试过。我们的长期目标是识别和理解控制神经元兴奋性的星形胶质细胞机制。该特定应用的目的是确定星形胶质细胞肿胀和肿胀诱发的谷氨酸释放的特定操作如何导致原位和体内神经元兴奋性的变化。中心假设是星形胶质细胞肿胀和星形胶质细胞体积调节阴离子通道（VRAC）释放谷氨酸对于提高原位和体内神经元兴奋性是必要且充分的。该研究的基本原理是，识别控制神经元兴奋性的新星形胶质细胞途径将为治疗神经系统疾病和神经退行性疾病提供新的星形胶质细胞药物靶点。在强有力的初步数据的指导下，中心假设将通过追求三个具体目标来检验：1）确定星形胶质细胞肿胀诱发的谷氨酸释放对于增加原位神经元兴奋性所必需的程度； 2）确定星形胶质细胞肿胀诱发的谷氨酸释放足以增加原位神经元兴奋性的程度； 3)确定星形胶质细胞肿胀对体内神经元兴奋性控制的贡献。将使用膜片钳和转基因方法选择性地操纵星形胶质细胞肿胀和谷氨酸释放，并在记录急性海马切片 CA1 锥体神经元 NMDA 受体活性期间对星形胶质细胞体积变化进行实时成像（目标 1 和 2），以及效果将在体内测定低渗透压、高渗透压和选择性抑制剂对星形细胞体积变化和神经元兴奋性的影响（目标 3）。我们认为，我们的方法是创新的，因为它代表了评估星形胶质细胞 Ca2+ 依赖性胶质细胞传递在调节神经元兴奋性中的作用的现状的重大背离，并且因为我们已经开发出技术并证明在我们手中是可行的，有选择地和特异性地操纵星形胶质细胞体积变化和谷氨酸释放。拟议的研究意义重大，因为一旦控制神经元兴奋性的星形胶质细胞机制得到澄清，就可以设计出新的星形胶质细胞定向疗法来防止神经元兴奋性过度水平，同时保持神经元兴奋性的基础水平和正常认知功能完好无损。这些知识还将提供新的策略来治疗与细胞体积变化（包括各种形式的水肿）相关的神经系统疾病，同时也从根本上增进我们对神经胶质-神经元相互作用的理解。