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

• 批准号: 10487823
• 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
• 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/10487823
• 关键词: Acute; Affect; Animals; Antiepileptic Agents; Antiepileptogenic; Area; Attenuated; Axon; Biochemical; Brain; Brain Injuries; Cerebellum; Cessation of life; Characteristics; Chemicals; Chronic; Cognitive; Conflict (Psychology); 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 (Brain); 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; Pharmacology; 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; postsynaptic; receptor; receptor expression; receptor function; response; response to injury; tool; virtual

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.

该项目的重点是由创伤性脑损伤引起的细胞和分子变化 （TBI），特别是那些影响海马中GABA能信号传导的人。适应不良的变化 细胞和分子特性有助于TBI的认知和神经精神后遗症，以及 癫痫发作。慢性细胞和分子改变引起TBI后功能障碍，以及 诱导这些慢性变化的TBI触发的近端因子尚不完全理解。 小胶质细胞是大脑的常驻免疫细胞，在健康的大脑中起有益的功能，但在 对伤害的反应他们的行为可能是适应不良的，有害的，并放大了TBI的后果。 因此，小胶质细胞及其炎症信号传导是引发病理生理的候选因素 TBI后的细胞和分子变化。先前的工作已经确定了下调 外突触GABA受体是海马中TBI的一致特征。提出了实验 这里将测试以下假设：i）小胶质细胞激活的衰减将限制TBI诱导的变化 在突触外GABA受体的表达和功能以及II）小胶质细胞激活的衰减将会 减少TBI后自发癫痫发作的发生率（癫痫发生）。 结合贴片钳电生理学和免疫组织化学技术， 海马在海马中的表达和功能（GABAA和GABAB）的表达和功能 神经元将在严重TBI（受控皮质影响，CCI）的模型中进行评估。评估角色 TBI后这些分子改变中的小胶质细胞，这是一种强大的药理学工具 将使用脑脑小胶质细胞（PLX5622，CSF1-R抑制剂）。 PLX5622处理的动物将是 暴露于CCI，允许评估TBI后的功能分子改变是 取决于小胶质细胞活化。具体而言，提出的实验将确定 TBI后的伸展性GABA受体取决于小胶质细胞活化。作为此目标的一部分，其他 将检查受TBI（丘脑，小脑）影响的区域，以进行CCI相关的变化 外突触GABA受体功能。 也将研究TBI和结果的细胞效应，以评估其对其对 小胶质细胞活化。使用在CCI之前用PLX5622耗尽小胶质细胞的方法 TBI后神经元死亡的病程和大小（对于所有神经元和特定的神经元亚型） 将根据对照和PLX5622处理的动物确定。苔藓纤维发芽（ DGGC轴突对损伤的病理生理作用反应）是发生的另一种细胞变化 由于TBI的结果；苔藓纤维发芽将被量化并在两者之间进行比较 组。据信，在此提出的研究的细胞和分子变化都有助于 癫痫发生和癫痫发作，但不论这些特定的细胞/分子如何改变 识别CCI后对癫痫发生的显着小胶质细胞依赖性作用最大 重要性。视频EEG监视将用于确定自发癫痫发作的发生率 （即癫痫病）和CCI后对照和PLX5622处理的动物进行癫痫发作。这些数据 将提供证据以支持（或反驳）小胶质细胞在CCI后癫痫发生中起重要作用。 需要这些见解来为未来的调查和治疗方法提供信息。