Astrocytes and Ischemic Brain Injury

心脏骤停幸存者最可怕的残疾之一是神经功能障碍。全球大脑 心脏骤停时出现的缺血会导致海马区CA1锥体神经元的迟发性丢失 而附近的齿状回(DG)则相对抵抗。尽管在海马神经元方面做了很多工作 尽管如此，我们对缺血对海马星形胶质细胞的影响知之甚少。这笔赠款试图理解 星形胶质细胞在海马选择性易损性中的作用。星形胶质细胞是许多大脑所必需的。 功能包括突触传递，代谢和离子平衡，抗氧化防御， 炎症、血脑屏障和营养支持。这项建议将研究三个方面的问题 海马区星形胶质细胞存活及对缺血和类缺血应激的反应。在目标1中，线粒体 功能将通过缺血和再灌流进行评估。线粒体对能量和能量都很重要 生产和调节细胞死亡。海马器型脑片培养，可再生 选择性CA1易损性，从海马区这两个亚区分离的星形胶质细胞 用于电生理研究和实时成像。线粒体变化的时程 星形胶质细胞再灌流过程中膜电位、活性氧和细胞内钙的变化 将对CA1和DG进行评估。比较脆弱地区和抵抗地区将允许歧视 重要的变化。呼吸功能和线粒体复合体活性也将被测量。目标2将 重点研究星形胶质细胞谷氨酸摄取在缺血和再灌流过程中的变化。早期减损 星形胶质细胞摄取谷氨酸危及邻近神经元，我们发现早期GLT-1在 CA1星形胶质细胞。将进行谷氨酸摄取和转运体表达的详细研究。ATP 将监测维持膜电位和谷氨酸摄取所需的存储。AIM 3将使用 伴侣热休克蛋白70在星形胶质细胞中的选择性过表达及GLT-1的诱导保护作用 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。把这些放在一起 研究将提供海马区星形胶质细胞缺血反应的图像，并将星形胶质细胞功能障碍与 海马区选择性神经元损伤。维持和改善星形胶质细胞的功能提供了一种新的 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.