MITOCHONDRIA RELATED EVENTS IN TRAUMATIC BRAIN INJURY

创伤性脑损伤（TI）后的中心事件是短暂的或持续的电生理功能损害，表现为昏迷、“脑震荡”或神经功能缺损。静息膜电位的持续降低，以及随后的神经元和轴突膜不能充分恢复，是引起这些效应的最可能机制。该应用围绕中心假设，即线粒体功能障碍和减少的离子泵送，导致生物能量衰竭，是决定TBI后神经元和轴突恢复的主要限制因素。在这个应用中，我们建立在我们以前的研究，证明了大量的兴奋性神经递质释放TBI后，导致钙内流。这反过来又会损害线粒体、神经丝和第二信使介导的离子通道，以及许多其他事件。这些问题将在临床和实验室环境中进行探讨。具体而言，在大鼠TBI模型中，我们将使用免疫组织化学，分子生物学，电生理学和行为测试来验证钙介导的抑制性GABA Cl通道损伤加剧神经元损伤的假设，从而使结果恶化，GABA激动剂改善结果。我们将直接测量细胞色素氧化酶活性，以显示TBI后线粒体功能受损，并且我们将证实用环孢菌素A特异性阻断线粒体转换孔（MPT）将防止这些变化并改善结果。在严重的头部受伤的患者，同时微透析，和一个新的同轴深度电极，连同组织氧/CO2/pH传感器系统，将被放置在同一个大脑区域，以测试增加的氧张力的影响，和环孢菌素A下的神经化学和神经生理事件的相互作用。我们将使用AVDO 2、AVD乳酸盐和AVD葡萄糖来评估整体治疗效果，并将其与CBF和MRI参数相关联。最后，我们将使用MRI水映射，弥散加权成像和CBF映射，以显示脑肿胀，这几乎总是由TBI引起的细胞毒性水肿。这些方法还将检验环孢菌素A将改善细胞毒性水肿，以及N乙酰天冬氨酸光谱学将构成人TBI中神经元和神经元损伤的“替代标记物”的假设。因此，这些新的技术，通过一套紧密结合的实验室和临床研究，将产生新的机制的见解，并具体评估环孢素A和其他几个推定的新疗法在TBI。

The central event after traumatic brain injury (TI) is the transient, or ongoing impairment of electrophysiological function, manifest as coma, "concussion" or neurological deficit. Persistent reduction in the Resting Membrane Potential, and consequent failure to adequately re-polarize neuronal and axonal membranes, are the most likely mechanisms for eliciting these effects. This application revolves around the central hypothesis that mitochondrial dysfunction and reduced ionic pumping, leading bioenergetic failure, is the major limiting factor, determining neuronal and axonal recovery after TBI. In this application, we build upon our previous studies, demonstrating massive excitatory neurotransmitter release after TBI, leading to calcium influx. This in turn damages mitochondria, neurofilaments, and second-messenger mediated ion channels, among many other events. These issues will be explored in the clinic and laboratory settings. Specifically, in rat TBI models, we will use immunohistochemistry, molecular biology, electrophysiology, and behavioral testing to validate the hypothesis that calcium-mediated damage to inhibitory GABA Cl channels exacerbates neuronal damage, and thus worsens outcomes, and that GABA agonists improve outcome. We will directly measure cytochrome oxidase activity, to show that mitochondria are functionally impaired after TBI, and we will posit that specific blockade of the Mitochondria Transition Pore (MPT) with Cyclosporin A, will prevent these changes, and improve outcome. In severely head injured patients, simultaneous microdialysis, and a new coaxial depth electrode, together with a tissue oxygen/CO2/pH sensor system, will be placed in the same brain region to test the effect of increased oxygen tension, and Cyclosporin A under the interplay of neurochemical and neurophysiological events. We will use AVDO2, AVD lactate, and AVD glucose to assess global therapy effects, and relate them to CBF and MRI parameters. Finally, we will use MRI water mapping, Diffusion Weighted Imaging, and CBF mapping, to show that the brain swelling, which almost always follows TBI is due to cytotoxic edema. These methods will also test the hypothesis that Cyclosporin A will ameliorate cytotoxic edema, and that N Acetyl Aspartate spectroscopy will constitute a "surrogate marker" for mitochondrialy, and neuronal damage in human TBI. Thus, these novel techniques, through a tightly integrated set of laboratory and clinical studies, will yield new mechanistic insights, and specifically evaluate Cyclosporin A and several other putative new therapies in TBI.