Astrocytes and Ischemic Brain Injury

心脏骤停幸存者最害怕的残疾之一是神经功能障碍。全脑 缺血，如心脏骤停所见，导致海马CA 1锥体神经元的延迟丧失 而邻近的齿状回（DG）相对抵抗。尽管对海马神经元的研究很多， 损伤，很少有人知道缺血对海马星形胶质细胞的影响。这份补助金旨在了解 星形胶质细胞对海马选择性易损性的贡献。星形胶质细胞对许多大脑 功能包括突触传递、代谢和离子稳态、抗氧化防御， 炎症、血脑屏障和营养支持。本建议将研究三个方面， 海马星形胶质细胞存活和对缺血和缺血样应激的反应。在aim 1中， 用局部缺血和再灌注评估功能。线粒体对于能量和 生产和调节细胞死亡。海马器官型切片培养， 选择性CA 1脆弱性，从海马的这两个亚区分离的星形胶质细胞将被 用于电生理学研究和真实的时间成像。线粒体变化的时程 再灌注期间星形胶质细胞膜电位、活性氧和细胞内钙 将评估CA 1和DG。比较脆弱和抵抗地区将允许区分 重要的变化。还将测量呼吸功能和线粒体复合体活性。目标2将 重点关注缺血和再灌注时星形胶质细胞谷氨酸摄取的变化。早期损害 星形胶质细胞摄取谷氨酸会危及邻近的神经元，我们已经发现， CA 1星形胶质细胞。将进行谷氨酸摄取和转运蛋白表达的详细研究。ATP 将监测维持膜电位和谷氨酸摄取所需的储存。目标3将使用 在星形胶质细胞中选择性地过表达伴侣Hsp 70，并诱导GLT-1作为保护性 策略和评估星形胶质细胞功能的变化以及神经元存活的变化。综合这些 研究将提供海马星形胶质细胞缺血反应的图片，并将星形胶质细胞功能障碍与 海马选择性神经元损伤。维持和改善星形胶质细胞功能提供了一种新的 用于开发治疗方法以改善心脏骤停后的神经功能。

One of the most feared disabilities in survivors of cardiac arrest is neurological impairment. Global cerebral schemia, as seen with cardiac arrest, causes delayed loss of CA1 pyramidal neurons in the hippocampus while the nearby dentate gyrus (DG) is relatively resistant. Despite much work on hippocampal neuronal njury, little is known of the effects of ischemia on hippocampal astrocytes. This grant seeks to understand the contribution of astrocytes to hippocampal selective vulnerability. Astrocytes are essential to many brain functions including synaptic transmission, metabolic and ionic homeostasis, antioxidant defense, inflammation, the blood brain barrier, and trophic support. This proposal will study three aspects of hippocampal astrocyte survival and response to ischemia and ischemia-like stress. In aim 1, mitochondrial function will be assessed with ischemia and reperfusion. Mitochondria are important both for energy production and for the regulation of cell death. Hippocampal organotypic slice cultures, which reproduce selective CA1 vulnerability, and astrocytes isolated from these two subregions of the hippocampus will be used for electrophysiological studies and real time imaging. The timecourse of changes in mitochondrial membrane potential, reactive oxygen species, and intracellular calcium during reperfusion in astrocytes in CA1 and DG will be assessed. Comparing the vulnerable and resistant areas will allow discrimination of important changes. Respiratory function and mitochondrial complex activity will also be measured. Aim 2 will focus on changes in astrocyte glutamate uptake with ischemia and reperfusion. Early impairment of glutamate uptake by astrocytes endangers neighboring neurons, and we have found early loss of GLT-1 in CA1 astrocytes. Detailed studies of glutamate uptake and transporter expression will be performed. ATP stores required for maintaining membrane potential and glutamate uptake will be monitored. Aim 3 will use overexpression of the chaperone Hsp70 selectively in astrocytes and induction of GLT-1 as protective strategies and assess changes in astrocyte function as well as changes in neuronal survival. Together these studies will provide a picture of hippocampal astrocyte ischemic response and link astrocyte dysfunction to selective neuronal injury in hippocampus. Maintaining and improving astrocyte function provides a novel target for developing therapies to improve neurological function following cardiac arrest.