The Epileptogenic Effect of Perinatal Hypoxia

描述（由申请人提供）：与缺氧脑病相关的新生儿癫痫发作对常规AED治疗是难治性的，并且与长期神经发育迟缓、认知障碍和癫痫有关。新生儿的大脑从根本上不同于成人的大脑，并且由于活动依赖性突触发生和皮层发育所必需的生理高兴奋性功能，新生儿的大脑特别容易受到癫痫刺激的影响。在过去的15年里，该研究项目已经建立了一个可靠的啮齿动物新生儿缺氧发作模型，确定了特定的年龄依赖性机制，验证了这些靶点在人类新生儿皮质组织中的年龄特异性表达，并使用临床可用的药物在针对这些机制的大鼠中进行了治疗试验。在我们的啮齿动物的新生儿癫痫发作模型中，我们已经表明，癫痫发作后48小时全身施用谷氨酸受体拮抗剂可以预防长期后果，因此可能是疾病的改善。目前的建议将集中在这个即时和早期的癫痫发作窗口，以确定现有蛋白质的快速翻译后修饰和调节机制，这些机制可能是可预防和/或可逆的。目的1。确定癫痫引起的嗜离子性谷氨酸受体功能改变的时间过程，以及它们是否与受体亚基的翻译后修饰有关。目标2。确定AMPARs和NMDARs的翻译后修饰是否与体内和体外缺氧癫痫发生仅相关或机制相关。目标3。确定雷帕霉素（mTOR）信号通路的哺乳动物靶点是否代表了预防缺氧癫痫引起的高兴奋性的治疗靶点。目标4。继续我们的人体组织研究谷氨酸受体表达的成熟模式，并研究mTOR通路激活是否可以在缺氧足月婴儿死后的脑组织中检测到。我们的初步结果显示，许多这些早期癫痫引起的蛋白质变化与在突触可塑性模型中观察到的变化惊人地相似。这一建议的总体假设是，这些早期变化代表了抗癫痫发生的干预点，即使在癫痫发作被诱发之后。这一资助期的主要重点是在这48小时窗口期内确定这些分子靶点，并用已知对这些靶点具有调节活性的现有现货药物进行干预。公共卫生相关性：与缺氧脑病相关的新生儿癫痫发作对常规AED治疗是难治性的，并且与长期神经发育迟缓、认知障碍和癫痫有关。新生儿的大脑从根本上不同于成人的大脑，并且由于活动依赖性突触发生和皮层发育所必需的生理高兴奋性功能，新生儿的大脑特别容易受到癫痫刺激的影响。在过去的15年里，这个研究项目（NS31718）已经建立了一个可靠的新生儿缺氧发作模型，确定了特定的年龄依赖性机制，验证了这些靶点在人类新生儿皮质组织中的年龄特异性表达，并使用临床可用的药物在大鼠中针对这些机制进行了治疗试验。通过直接和合作的努力，该研究项目在过去40多年中，为新生儿癫痫发作治疗试验网络（NESTT）提出了仅有的两种药物，这些药物被考虑用于新生儿癫痫发作的首批治疗试验。这两种药物分别是托吡酯（TPM）和布美他尼（bumetanide），前者靶向未成熟大脑中过度表达的AMPARs，后者是一种特异性Cl-转运体NKCC1的阻滞剂，我们已发现NKCC1在新生儿大脑中过度表达，这导致GABA激动剂（巴比妥类药物、苯二氮卓类药物）在这一人群中缺乏疗效。值得注意的是，AMPAR拮抗剂，包括TPM，在初始癫痫发作后使用时可有效预防长期后果，因此这可能是fda批准的第一种抑制新生儿癫痫发生的药物。目前的建议旨在完善我们对这种新型抗癫痫作用的理解，并潜在地阐明可用于这一独特人群的治疗干预的其他靶点。

DESCRIPTION (provided by applicant): Neonatal seizures associated with hypoxic encephalopathy are refractory to conventional AED therapy, and are associated with long term neurodevelopmental delay, cognitive impairment and epilepsy. The newborn brain is fundamentally different from the adult brain, and is uniquely susceptible to epileptic stimuli as a function of physiological hyperexcitability required for activity dependent synaptogenesis and cortical development. In the prior 15 years, this research program has generated a reliable rodent model of neonatal hypoxic seizures, identified specific age-dependent mechanisms, validated the age specific expression of these targets in human neonatal cortical tissue, and executed therapeutic trials in the rat targeted towards these mechanisms, using clinically available drugs. In our rodent models of neonatal seizures, we have shown that systemic administration of glutamate receptor antagonists for 48 hrs following seizures can prevent the long term consequences, and hence may be disease modifying. The present proposal will focus on this immediate and early post seizure window to identify rapid post-translational modifications of existing protein and regulatory mechanisms governing the translation of protein from of pre-existing mRNA that may be preventable and/or reversible. Aim 1. To determine the time course of seizure-induced changes in ionotropic glutamate receptor function, and whether they are associated with post-translational modification of receptor subunits. Aim 2. To establish whether post-translational modifications in AMPARs and NMDARs are merely correlated or mechanistically related to in hypoxic seizure-induced epileptogenesis in vivo and in vitro. Aim 3. To determine whether the mammalian target of rapamycin (mTOR) signaling pathway represents a therapeutic target for prevention of hypoxic-seizure induced hyperexcitability. Aim 4. To continue our human tissue study of maturational patterns of glutamate receptor expression and investigate whether mTOR pathway activation can be detected in postmortem human brain tissue from hypoxic term infants. Our preliminary results reveal that many of these early seizure induced changes in proteins are strikingly similar to those observed in models of synaptic plasticity. The overall hypothesis of this proposal is that these early changes represent intervention points for antiepileptogenesis, even after the seizures have been induced. A major focus for this funding period is to identify these molecular targets in this 48 hr window and intervene with available off-the-shelf drugs that are known to have modulatory activity at these targets. PUBLIC HEALTH RELEVANCE: Neonatal seizures associated with hypoxic encephalopathy are refractory to conventional AED therapy, and are associated with long term neurodevelopmental delay, cognitive impairment and epilepsy. The newborn brain is fundamentally different from the adult brain, and is uniquely susceptible to epileptic stimuli as a function of physiological hyperexcitability required for activity dependent synaptogenesis and cortical development. In the prior 15 years, this research program (NS31718) has generated a reliable model of neonatal hypoxic seizures, identified specific age-dependent mechanisms, validated the age specific expression of these targets in human neonatal cortical tissue, and executed therapeutic trials in the rat targeted towards these mechanisms, using clinically available drugs. Through direct and collaborative efforts, this research program has been critical to proposing the only 2 agents being considered for the first therapeutic trials by the Neonatal Seizure Treatment Trial Network (NESTT) for neonatal seizures in the last 4+ decades. The 2 agents are topiramate (TPM), which we have shown targets the AMPARs that are overexpressed in the immature brain, and bumetanide, a blocker of a specific Cl- transporter NKCC1 that we have shown to be overexpressed in the newborn brain and which contributes to the lack of efficacy of GABA agonists (barbiturates, benzodiazepines) in this population. Notably AMPAR antagonists, including TPM, are effective at preventing long term consequences when administered after the initial seizures, and hence this may be the first FDA-approved agent to inhibit epileptogenesis in neonates. The present proposal aims to refine our understanding of this novel antiepileptogenic effect, and potentially elucidate other targets that can be used for therapeutic intervention in this unique population.