GLUTAMATE EXCITOTOXICITY

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 谷氨酸兴奋性毒性是神经元细胞死亡的重要介质，并可能导致中风、癫痫和创伤性脑损伤的病理。在长期谷氨酸暴露期间神经元损伤的主要机制是由于Ca 2+通过NMDA谷氨酸受体进入并随后通过线粒体螯合Ca 2+。这导致线粒体Ca 2+过载，ROS产生增加，生物能量学破坏和细胞结构丧失。 替代理论表明，Ca 2+和Na+的积累可能导致ATP消耗泵对ATP的需求增加，从而导致细胞内ATP的消耗。ATP耗竭条件是细胞死亡的决定因素还是表现形式仍然是一个问题。 BRC与Mattson实验室（NIA）合作，旨在评估单个海马神经元的耗氧量，以深入了解暴露于谷氨酸盐期间的线粒体呼吸能力。最大耗氧量是临界ATP消耗的良好指标，如在暴露于线粒体解偶联剂化合物期间所观察到的。在此提议之前，仅在整个神经元群体中评估了氧消耗。这导致了诸如对药物的时间响应性以及对同质细胞群体的需要等问题。随着自参考氧微传感器的发展，BRC能够测量氧通量，从而在单细胞水平上测量氧消耗。 通过将这种技术与共聚焦显微镜相结合，预计将建立线粒体膜电位，细胞内Ca 2+和氧消耗之间的时间关系，并为兴奋性毒性的潜在机制提供线索。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Glutamate excitotoxicity is an important mediator of neuronal cell death and may contribute to the pathology of stroke, epilepsy and traumatic brain injury. The chief mechanism of neuronal injury during prolonged glutamate exposure is due to Ca2+ entry through NMDA glutamate receptors and consequent sequestration of Ca2+ by mitochondria.. This leads to mitochondrial Ca2+ overload, increase in ROS production, disruption of bioenergetics and loss of cellular architecture. Alternative theories suggest that accumulation of Ca2+ and indeed Na+ may lead to an increase in ATP demand from ATP-consuming pumps and consequent depletion of intracellular ATP. It remains a question whether ATP depleting conditions are a determinant or a manifestation of cell death. In conjunction with the Mattson Laboratory (NIA), the BRC has aimed to assess oxygen consumption in single hippocampal neurons in order to gain insight into mitochondrial respiratory capacity during exposure to glutamate. Maximal oxygen consumption is a good indicator of critical ATP depletion, as observed during exposure to mitochondrial uncoupler compounds. Oxygen consumption has only been assessed in whole neuronal populations prior to this proposal. This leads to problems such as the time responsiveness to drugs as well as the need for a homogeneous population of cells. With the development of self-referencing oxygen microsensors, the BRC is able to measure oxygen flux and therefore oxygen consumption at the single cell level. By combining this technique with confocal microscopy, it is anticipated that temporal relationships between mitochondrial membrane potential, intracellular Ca2+ and oxygen consumption will be established and provide clues to the underlying mechanism of excitotoxicity.