POSTNATAL DEVELOPMENT OF VULNERABILITY TO BRAIN INJURY

缺氧缺血性脑病是远期脑损伤的重要原因 婴儿、儿童和成人的神经系统疾病。它有多脆弱 脑对缺氧缺血的损伤关键取决于出生后的成熟。 神经元谷氨酸受体的激活在脑出血中起主要作用。 兴奋性中毒性神经变性是急性脑损伤的特征 缺氧-缺血。出生后成熟度在决定 对缺氧-缺血的脆弱性突出了需要精确的 对出生后成熟如何调节细胞内的理解 兴奋性毒性的成分。此应用程序的主要目标是 钙依赖的精确发育调控特征 导致兴奋性毒性神经变性的过程。要做到这一点 目标，提出了以下具体目标：(I)确定血浆如何 膜Na~+/Ca~(2+)交换、内质网Ca~(2+)截留与线粒体Ca~(2+) 封存随着出生后的发育而变化。培养的海马神经元 从P0-5、P10-15和P18-25大鼠将暴露于 细胞内[Ca~(2+)]，以及线粒体、内质网和血浆的作用 膜Na~+/Ca~(2+)交换器使细胞内[Ca~(2+)]恢复到基线水平 将会被测量。(2)评估发展变化对这些方面的重要性 决定NMDA易感性的动态平衡机制。NMDA引起的损失 的活性将在同龄大鼠的神经元培养中进行测量 团体在存在和不存在对这些机制的具体封锁。 (Iii)确定线粒体钙积聚在心肌细胞内钙离子浓度升高中的作用。 发生在出生后的线粒体膜电位的耗散 在NMDA暴露期间的发展。NMDA对增量psi的影响将在 来自相同年龄组的神经元及其与线粒体变化的相关性 [Ca~(2+)]和有无线粒体时的胞浆[Ca~(2+)] Na+/Ca2+交换受阻。分离的单转运体和钠/钙离子交换活性 将在P0-5和P18-25大鼠的通透性神经元中进行测量。(四) 测定线粒体钙蓄积的改变程度 有助于后天的兴奋性易损性的发展。NMDA 诱导的神经元死亡将在有无阻断的情况下进行测量 Na~+/Ca~(2+)交换器和线粒体转换孔。

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.