Regulation of extraysynaptic GABA-A receptors in health and disease

突触外 GABA-A 受体在健康和疾病中的调节

基本信息

批准号：
10630188
负责人：
Christopher Bruce Ransom
金额：
--
依托单位：
VA PUGET SOUND HEALTHCARE SYSTEM
依托单位国家：
美国
项目类别：
财政年份：
2015
资助国家：
美国
起止时间：
2015-10-01 至 2026-04-30
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10630188
关键词：
Acute Affect Animals Antiepileptic Agents Antiepileptogenic Area Attenuated Axon Biochemical Brain Brain Injuries Cerebellum Cessation of life Characteristics Chemicals Chronic Cognitive Data Dependence Diet Disease Down-Regulation Electroencephalography Electrophysiology (science)Epilepsy Epileptogenesis Exposure to Functional disorder Future G-Protein-Coupled Receptors GABA Receptor GABA-A Receptor Health Hippocampus Histologic Human Resources Immune Incidence Inflammatory Injury Interneurons Intractable Epilepsy Investigation Knowledge Macrophage Colony-Stimulating Factor Receptor Memory Mental Depression Microglia Military Personnel Modeling Molecular Monitor Mus Neurologic Symptoms Neurons Neurotransmitter Receptor Neurotransmitters Outcome Penetration Post-Traumatic Epilepsy Property Proteins Regulation Resistance Role Seizures Services Severities Signal Transduction Slice Stroke Synapses Techniques Testing Thalamic structure Therapeutic Time Traumatic Brain Injury Veterans Walking Work active duty aging population antagonist attenuation axonal sprouting brain cell controlled cortical impact dentate gyrus effective therapy experimental study falls granule cell high risk improved inhibitor injured insight military veteran mossy fiber neuron loss neuropsychiatry novel patch clamp pharmacologic postsynaptic receptor receptor expression receptor function response response to injury tool virtual

项目摘要

This project is focused on the cellular and molecular changes caused by traumatic brain injury (TBI), specifically those affecting GABAergic signaling in the hippocampus. Maladaptive changes in cellular and molecular properties contribute to the cognitive and neuropsychiatric sequelae of TBI, and epileptic seizures. The chronic cellular and molecular alterations causing dysfunction after TBI, and the proximal factors triggered by TBI that induce these chronic changes, are incompletely understood. Microglia, the resident immune cells of the brain, serve beneficial functions in the healthy brain but in response to injury their actions can be maladaptive, injurious, and magnify the consequences of TBI. As such, microglia and their inflammatory signaling are candidate factors to trigger pathophysiological cellular and molecular changes after TBI. Prior work has established that downregulation of extrasynaptic GABA receptors is a consistent feature of TBI in the hippocampus. Experiments proposed here will test the hypotheses that: i) attenuation of microglia activation will limit TBI-induced changes in extrasynaptic GABA receptor expression and function and ii) attenuation of microglia activation will decrease the incidence of spontaneous seizures after TBI (epileptogenesis). Using a combination of patch-clamp electrophysiology and immunohistochemical techniques, the expression and function of extrasynaptic GABA receptors (both GABAA and GABAB) in hippocampal neurons will be assessed in a model of severe TBI (controlled cortical impact, CCI). To assess the role of microglia in these molecular alterations after TBI, a powerful pharmacological tool that dramatically depletes brain microglia will be used (PLX5622, a CSF1-R inhibitor). PLX5622-treated animals will be exposed to CCI, allowing the assessment of whether functional molecular alterations after TBI are dependent on microglia activation. Specifically, the proposed experiments will determine if changes in extasynaptic GABA receptors after TBI are dependent on microglia activation. As part of this aim, other areas affected by TBI (thalamus, cerebellum) will be examined for CCI-associated changes in extrasynaptic GABA receptor function. The cellular effects of TBI and outcomes will also be investigated to assess their dependence on microglia activation. Using the approach of depleting microglia with PLX5622 prior to CCI, the time course and magnitude of neuronal death after TBI (for all neurons and specific interneuronal subtypes) will be determined for control and PLX5622-treated animals. Mossy fiber sprouting (the pathophysiological arborizing response of DGGC axons to injury) is another cellular change that occurs as a consequence of TBI; mossy fiber sprouting will be quantified and compared between the two groups. The cellular and molecular changes proposed for study here are all believed to contribute to epileptogenesis and seizures, but irrespective of these specific cellular/molecular changes the recognition of significant microglia-dependent effects on epileptogenesis after CCI is of greatest importance. Video-EEG monitoring will be used to determine the incidence of spontaneous seizures (i.e. epilepsy) and seizure characteristics after CCI in control and PLX5622-treated animals. These data will provide evidence to support (or refute) a significant role of microglia in epileptogenesis after CCI. These insights are needed to inform areas of future investigation and therapeutic approaches.

该项目专注于脑外伤引起的细胞和分子变化 (TBI)，特别是影响海马 GABA 信号传导的那些。适应不良的变化细胞和分子特性导致 TBI 的认知和神经精神后遗症，以及癫痫发作。 TBI 后导致功能障碍的慢性细胞和分子改变，以及 TBI 引发的导致这些慢性变化的近端因素尚不完全清楚。小胶质细胞是大脑的常驻免疫细胞，在健康的大脑中发挥有益的功能，但在对伤害的反应他们的行为可能是不适应的、有害的，并会放大 TBI 的后果。因此，小胶质细胞及其炎症信号是触发病理生理学的候选因素 TBI 后细胞和分子的变化。先前的工作已经确定下调突触外 GABA 受体是海马 TBI 的一致特征。提议的实验这里将测试以下假设：i) 小胶质细胞激活的减弱将限制 TBI 引起的变化突触外 GABA 受体表达和功能以及 ii) 小胶质细胞激活的减弱将减少 TBI（癫痫发生）后自发性癫痫发作的发生率。结合膜片钳电生理学和免疫组织化学技术，海马突触外 GABA 受体（GABAA 和 GABAB）的表达和功能神经元将在严重 TBI 模型（受控皮质冲击，CCI）中进行评估。评估角色小胶质细胞在 TBI 后这些分子改变中的作用，这是一种强大的药理学工具，可显着将使用消耗脑小胶质细胞的药物（PLX5622，一种 CSF1-R 抑制剂）。 PLX5622治疗的动物将暴露于 CCI，可以评估 TBI 后功能性分子改变是否依赖于小胶质细胞的激活。具体来说，拟议的实验将确定是否发生变化 TBI 后的突触外 GABA 受体依赖于小胶质细胞的激活。作为该目标的一部分，其他受 TBI 影响的区域（丘脑、小脑）将接受 CCI 相关变化的检查突触外 GABA 受体功能。还将研究 TBI 的细胞影响和结果，以评估其对小胶质细胞激活。在 CCI 之前使用 PLX5622 消耗小胶质细胞的方法，时间 TBI 后神经元死亡的过程和程度（对于所有神经元和特定的神经元间亚型）将针对对照和 PLX5622 治疗的动物进行确定。苔藓纤维发芽（ DGGC 轴突对损伤的病理生理树状反应）是发生的另一种细胞变化 TBI 的后果；苔藓纤维发芽将被量化并在两者之间进行比较组。这里提出的研究的细胞和分子变化都被认为有助于癫痫发生和癫痫发作，但无论这些特定的细胞/分子变化如何认识到 CCI 后小胶质细胞对癫痫发生的显着影响是最大的重要性。视频脑电图监测将用于确定自发性癫痫发作的发生率对照和 PLX5622 治疗动物 CCI 后（即癫痫）和癫痫发作特征。这些数据将提供证据支持（或反驳）小胶质细胞在 CCI 后癫痫发生中的重要作用。这些见解需要为未来的研究领域和治疗方法提供信息。