POSTNATAL DEVELOPMENT OF VULNERABILITY TO BRAIN INJURY

缺氧缺血性脑病是脑梗死患者长期 婴儿、儿童和成人的神经系统发病率。如何脆弱的 脑缺氧缺血性损伤的发生与生后发育密切相关。 神经元谷氨酸受体的激活在神经元的代谢中起主要作用。 兴奋性毒性神经变性，其特征是急性脑损伤， 缺氧缺血出生后成熟在决定 对缺氧缺血的脆弱性强调了精确的 了解出生后成熟如何调节细胞内 兴奋性毒性的成分。本申请的主要目的是 描述了钙依赖的精确发育调节 导致兴奋毒性神经变性的过程。实现这一 目的，提出了以下具体目标：（一）确定血浆 膜Na+/Ca ~（2+）交换、内质网Ca ~（2+）螯合和线粒体Ca ~（2+） 随出生后发育而变化。培养海马神经元 从P0 -5，P10 -15，和P18 -25大鼠将暴露于一个步骤增加， 细胞内[Ca 2 +]，以及线粒体，ER和血浆的贡献 膜Na+/Ca 2+交换器对细胞内[Ca 2 +]恢复至基线的影响 将被衡量。(ii)评估这些发展变化的重要性 确定NMDA的脆弱性的稳态机制。NMDA诱导损失 将在来自相同年龄大鼠的神经元培养物中测量存活率 在存在和不存在这些机制的具体封锁的情况下，这些群体。 (iii)确定线粒体Ca 2+积累在增加的 出生后线粒体膜电位的消散 在NMDA暴露期间的发育。NMDA对Δ psi的影响将在 来自相同的3个年龄组的神经元，并与线粒体的变化相关 [Ca2+]和胞浆[Ca 2 +]在存在和不存在线粒体 Na+/Ca 2+交换阻断。分离的单向转运体和Na+/Ca 2+交换活性 将在来自P0 -5和P18 -25大鼠的透化神经元中测量。（四） 确定线粒体Ca 2+积累的变化程度 有助于兴奋性毒性脆弱性的出生后发展。NMDA 将在存在和不存在阻断的情况下测量诱导的神经元死亡 Na+/Ca 2+交换器和线粒体过渡孔的功能。

Hypoxic-ischemic encephalopathy is an important cause of long-term neurological morbidity in babies, children, and adults. How vulnerable the brain is to hypoxic-ischemic injury depends critically on postnatal maturation. Activation of neuronal glutamate receptors plays a major role in the excitotoxic neurodegeneration that characterizes acute brain injury from hypoxia-ischemia. The importance of postnatal maturation in determining vulnerability to hypoxia-ischemia highlights the need for a precise understanding of how postnatal maturation regulates the intracellular components of excitotoxicity. The major objective of this application is to characterize the precise developmental regulation of the calcium-dependent processes that lead to excitotoxic neurodegeneration. To achieve this objective, the following Specific Aims are proposed: (i) Identify how plasma membrane Na+/Ca2+ exchange, ER Ca2+ sequestration and mitochondrial Ca2+ sequestration change with postnatal development. Hippocampal neurons cultured from P 0-5, P 10-15, and P 18-25 rats will be exposed to a step increase in intracellular [Ca2+], and the contributions of the mitochondria, ER, and plasma membrane Na+/Ca2+ exchanger to the return of intracellular [Ca2+] to baseline will be measured. (ii) Assess the importance of developmental changes to these homeostatic mechanisms in determining vulnerability to NMDA. NMDA-induced loss in viability will be measured in neuronal cultures from rats of the same age groups in the presence and absence of specific blockade of these mechanisms. (iii) Identify the role of mitochondrial Ca2+ accumulation in the increased dissipation of mitochondrial membrane potential that occurs during postnatal development during NMDA exposure. NMDA effects on delta psi will be measured in neurons from the same 3 age groups and correlated with changes in mitochondrial [Ca2+], and cytosolic [Ca2+] in the presence and absence of mitochondrial Na+/Ca2+ exchange blockade. Isolated uniporter and Na+/Ca2+ exchanger activity will be measured in permeabilized neurons from P 0-5 and P 18-25 rats. (iv) Determine the extent to which alterations in mitochondrial Ca2+ accumulation contribute to the postnatal development of excitotoxic vulnerability. NMDA induced neuronal death will be measured in the presence and absence of blockade of the Na+/Ca2+ exchanger and of the mitochondrial transition pore.