DELAYED NEURODEGENERATION IN THE IMMATURE BRAIN.

新生儿脑损伤会导致存活婴儿终身残疾，其中运动感觉障碍往往最为突出。 使用新生儿缺氧缺血性（H/I）脑损伤的Rice-Vannucci模型，我们已经表明腹侧基底丘脑的损伤与前脑损伤相比在发病时延迟（24小时），并表现出突出的凋亡结构特征。由于腹侧基底丘脑损伤发生在大多数新生儿脑损伤模型中，并可能导致感觉-运动整合异常，因此腹侧基底丘脑损伤可能导致运动和感觉障碍。患有脑瘫的孩子。在初步研究中，我们发现了生物化学证据，表明腹侧基底丘脑的细胞死亡是通过程序性细胞死亡机制发生的。细胞色素氧化酶组织化学表明，线粒体表明线粒体积累，并表现出增加的细胞色素氧化酶活性在H/I损伤后的第一个24小时。在新生儿缺氧-缺血后3-6小时，腹侧基底丘脑中的细胞色素氧化酶亚单位1蛋白表达也增加。腹侧基底丘脑线粒体细胞色素氧化酶组织化学和蛋白质表达的这些异常显着的外观，在24小时的神经变性和凋亡的外观。caspase-3在24小时内裂解成其活性形式的发现进一步支持了线粒体中的这些生化变化与H/I损伤后腹侧基底丘脑中的细胞凋亡相关的观点。最后，在初步研究中，线粒体相关促凋亡蛋白BAS在腹侧基底丘脑缺氧缺血后3至24小时之间上调。基于这些初步的数据，我们假设，在腹侧基底丘脑迟发性神经变性是细胞凋亡，并发生线粒体相关的凋亡蛋白的改变的结果。由于腹侧基底丘脑的迟发性神经变性可能为神经元的拯救提供了合理的机会，我们必须了解新生儿H/I脑损伤后迟发性细胞死亡的确切机制。为了实现这一目标，本提案的目的是1）证明新生儿缺氧-缺血后腹侧基底丘脑中的延迟神经变性是程序性细胞死亡，2）证明新生儿缺氧-缺血后腹侧基底丘脑中促凋亡蛋白BAX和巴克的表达增加，以及促凋亡和抗凋亡bcl-2家族蛋白相互作用的变化，和3）在新生H/I后BAX缺陷小鼠中显示神经保护作用。

Neonatal brain injury results in lifelong disabilities for surviving infants with motor sensory disabilities often most prominent. Using the Rice- Vannucci model for neonatal hypoxic-ischemic (H/I) brain injury, we have shown the injury to the ventral basal thalamus is delayed in onset (24 hours) compared to forebrain injury and exhibits prominent structural features of apoptosis. Because injury to the ventral basal thalamus occurs in most models of neonatal brain injury and likely results in abnormalities in sensory-motor integration, injury to the ventral basal thalamus may contribute to the motor and sensory handicaps. Suffered by children with cerebral palsy. In preliminary studies, we find biochemical evidence that cell death in the ventral basal thalamus occurs by a programmed cell death mechanism. Cytochrome oxidase histochemistry indicates that mitochondria indicates that mitochondria accumulate and exhibit increased cytochrome oxidase activity in the first 24 hours after H/I injury. Cytochrome oxidase sub-unit 1 protein expression in the ventral basal thalamus is also increased at 3-6 hours after neonatal hypoxia- ischemia. These abnormalities in mitochondrial cytochrome oxidase histochemistry and protein expression in the ventral basal thalamus significantly precede the appearance the appearance of neurodegeneration and apoptotic profiles at 24 hours. The finding of cleavage of caspase-3 into its active forms by 24 hours further supports the idea that these biochemical changes in mitochondria are associated with apoptosis in the ventral basal thalamus following H/I injury. Lastly, in preliminary studies the mitochondrial associated pro-apoptosis protein, BAS is up-regulated between 3 and 24 hours following hypoxia-ischemia in the ventral basal thalamus. Based on these preliminary data, we hypothesize that delayed neurodegeneration in the ventral basal thalamus is apoptosis and occurs as the result of alterations in mitochondrial associated apoptosis proteins. Because delayed neurodegeneration in the ventral basal thalamus may offer a reasonable opportunity for neuronal rescue, we must understand the precise mechanism of delayed cell death following neonatal H/I brain injury. To accomplish this goal, the aims of this proposal will 1) demonstrate that delayed neurodegeneration in ventral basal thalamus after neonatal hypoxia-ischemia is programmed cell death, 2) demonstrate increased expression of the pro-apoptosis proteins, BAX and BAK, and changes in pro and anti-apoptosis bcl-2 family protein interactions in the ventral basal thalamus following neonatal hypoxia- ischemia, and 3) demonstrate neuroprotection in BAX deficient mice following neonatal H/I.