Injury-induced Alterations in Limbic Functional Circuity

描述(申请人提供)：在美国，创伤性脑损伤(TBI)每21秒发生一次，每年困扰多达200万人，是年轻人和儿童死亡和残疾的主要原因。目前已知，最初的脑外伤损害会传播长期的继发性异质性病理，这是长期发病率的基础。海马体是一种对学习和记忆至关重要的大脑结构，也是癫痫发作的频繁启动部位，在脑损伤期间经常受到损害。然而，损伤诱导的细胞代谢、神经递质功能和突触可塑性的变化如何导致海马区局部兴奋性改变，从而导致创伤后认知障碍和癫痫发作，目前仍不清楚。我们的实验室已经阐明了受损海马区代谢和电生理改变之间的新联系。我们先前已经证实，抑制效果的减弱会损害齿状回的功能。此外，我们还发现了一些可能导致海马齿状回传入过滤效率降低和长时程增强抑制的分子和代谢适应，包括氯转运体KCC2的表达减少，NMDA受体介导的钙内流减少，以及必需氨基酸代谢的中断。我们的长期目标是开发有效的和耐受性良好的策略来改善与脑外伤相关的病理。这项应用的目的是了解损伤引起的海马区兴奋性和代谢变化的原因和后果。我们的初步数据导致了以下中心假设的提出：脑损伤导致神经元氨基酸代谢的改变导致海马区兴奋性的区域性变化，与氯运输和钙介导的信号传导中断一起，导致癫痫和认知障碍的易感性增加。为了验证这一假设，一个专注于阐明基本机制的多学科方法将检查兴奋和抑制功能，以及海马亚区的神经元代谢。对这些机制的透彻理解将为指导开发潜在的治疗方法以改善脑外伤患者的认知功能障碍和癫痫发作提供洞察力。公共卫生相关性：创伤性脑损伤(TBI)是一个重大的公共卫生问题，对我们的医疗体系有重大影响。对与创伤相关的残疾的年度成本进行的经济分析从45亿美元的直接支出(医疗保健和服务)到206亿美元的与伤害有关的工作损失和残疾不等。我们的长期目标是开发有效和耐受性良好的临床治疗策略，以减少或改善脑外伤患者的认知功能障碍和癫痫发作。

DESCRIPTION (provided by applicant): In the United States, traumatic brain injury (TBI) occurs every 21 seconds, afflicts up to two million people annually, and is the primary cause of death and disability in young adults and children. The initial TBI lesion is now known to propagate long-lasting secondary heterogeneous pathologies, which underlie long term morbidities. The hippocampus, a brain structure crucial for learning and memory and also a frequent site of seizure initiation, is often damaged during TBI. It is still unknown however, how injury-induced changes in cellular metabolism, neurotransmitter function, and synaptic plasticity lead to the altered regional hippocampal excitability that contributes to post traumatic cognitive impairment and seizures. Our laboratory has elucidated novel connections between metabolic and electrophysiological alterations in the injured hippocampus. We have previously established that diminshed inhibitory efficacy compromises dentate gyrus function. Moreover, we have identified several molecular and metabolic adaptations in hippocampal function that may underlie reduced dentate gyrus filtering efficiency of afferent input and suppression of hippocampal long-term potentiation, including reduced expression of the chloride transporter KCC2, reduced NMDA receptor mediated calcium influx, and disruption of essential amino acid metabolism. Our long-range goal is to develop effective and well-tolerated strategies for ameliorating pathologies associated with TBI. The objective of this application is to understand the causes and consequences of injury-induced alterations in hippocampal excitability and metabolism. Our preliminary data led to the formulation of the following CENTRAL HYPOTHESIS: TBI-induced alteration in neuronal amino acid metabolism causes regional changes in hippocampal excitability, which together with disruptions in chloride transport and calcium mediated signaling, results in increased susceptibility to seizures and cognitive deficit. To test this hypothesis, a multi-disciplinary approach focused on elucidating basic mechanisms will examine excitatory and inhibitory function, as well as neuronal metabolism in hippocampal subregions. A thorough comprehension of these mechanisms will provide insight for directing the development of potential therapies to ameliorate cognitive dysfunction and seizures in TBI patients. PUBLIC HEALTH RELEVANCE: Traumatic brain injury (TBI) is a major public health issue, which has a significant impact upon our healthcare system. Economic analyses of the annual cost of TBI-related disabilities range from $4.5 billion in direct expenditure (medical care and services) to $20.6 billion in injury-related work loss and disability. Our long-range goal is to develop effective and well-tolerated clinical management strategies for reducing or ameliorating cognitive dysfunction and seizures in TBI patients.