Molecular mechanisms linking early life seizures, autism and intellectual disabil

描述（由申请人提供）：我们寻求最终理解3个基本问题：(1)生命早期癫痫发作（ELS）是否会引发自闭症表型的智力残疾（ID） ？(2) ELS触发的哪些信号程序可能是这种表型的基础？(3)改善突触可塑性异常和体内表型的合理、长期的药物治疗是什么？我们的初步研究提供了电生理、药理学和生化证据，表明ELS诱导的慢性表型类似于其他遗传形式的ID和自闭症，如脆性X染色体（FRAX）伴FMRP功能障碍和结节性硬化症（TSC）伴mTOR功能障碍。我们提出三个具体目标，利用电生理、生化、免疫细胞化学和行为研究。研究将使用成年大鼠，在出生后进行单次盐诱导的ELS (P) 7。这些研究将进一步研究mGluR-LTD电生理测量改变的机制，并验证ELS导致与其他遗传形式的自闭症相似的表型的假设。将与年龄匹配的生理盐水注射对照组进行比较。具体目标1：确定ELS后观察到的mglur依赖性LTD增强的机制。这将验证mglur依赖性LTD在ELS后发生改变的假设，这种改变类似于基因破坏FMRP表达介导的改变，并且可以以类似的方式在药理学上进行修改。特异性目标2：表征ELS后与S6激酶（SK1）过度激活相关的信号通路。这将验证以下假设，即信号通路在ELS后发生改变，其方式与FRAX和TSC中分别由FMRP表达中断和mTOR过度活跃介导的方式相似。具体目标3：进一步表征ELS后的行为和电图体内表型。这将验证一种假设，即在异常恐惧条件反射之外的行为模式是由与自闭症样表型一致的ELS诱导的。通过确定ELS后增强LTD的药理学调节剂，我们将确定这种可塑性的改变是否与FRAX和TSC相关的改变具有关键特征。在FRAX和TSC中提出的药物干预措施反映了我们在这里提出的研究。我们的研究将告知是否其他形式的ID和自闭症可能共享它们的药理学敏感性，并确定其他潜在的治疗靶点。这些研究将推进新的假设，即FMRP功能障碍可以在ID和/或FRAX以外的自闭症中看到。这可能会影响所有原因的ID和/或自闭症的治疗策略。我们的研究结果将支持我们的假设，即癫痫发作作为一种外部环境因素，直接影响自闭症和/或自闭症表型的发展。这些假设不能直接在病人身上得到检验。使用我们新颖的ELS触发具有自闭症表型的ID动物模型，可以更直接地解决这些难以捉摸的临床问题。

DESCRIPTION (provided by applicant): We seek to ultimately understand 3 basic questions: (1) Do early-life seizures (ELS) trigger intellectual disability (ID) with an autistic phenotype? (2) What signaling programs triggered by ELS potentially underlie this phenotype? (3) What are the rational, long-term pharmacological treatments to improve the abnormalities in synaptic plasticity and the in vivo phenotype? Our preliminary studies provide electrophysiological, pharmacological and biochemical evidence to suggest that ELS induces a chronic phenotype similar to other genetic forms of ID and autism such as Fragile X (FRAX) with FMRP dysfunction and Tuberous Sclerosis (TSC) with mTOR dysfunction. We propose three specific aims, utilizing electrophysiological, biochemical, immuno-cytochemistry and behavioral studies. Studies will use adult rats following a single kainate-induced ELS at post-natal day (P) 7. These studies will further investigate the mechanisms underlying altered mGluR-LTD measured electrophysiologically and test the hypothesis that ELS leads to a phenotype similar to other genetic forms of autism. Comparisons will be made to age-matched saline injected controls. Specific Aim 1: Determine the mechanisms underlying enhanced mGluR-dependent LTD observed following ELS. This will test the hypothesis that mGluR-dependent LTD is altered following ELS similar to that mediated by genetically disrupted FMRP expression and can be modified pharmacologically in a similar fashion. Specific Aim 2: Characterize the signaling pathways associated with S6 kinase (SK1) hyperactivation following ELS. This will test the hypothesis that signaling pathways are altered following ELS in a similar fashion to that mediated by disrupted FMRP expression and hyperactive mTOR, as in FRAX and TSC, respectively. Specific Aim 3: Further characterize the behavioral and electrographic in vivo phenotype following ELS. This will test the hypothesis that behavioral modalities beyond abnormal fear conditioning are induced by ELS that are consistent with an autism-like phenotype. By determining the pharmacological modulators of enhanced LTD following ELS, we will determine if this alteration in plasticity shares key features with that associated with FRAX and TSC. The pharmacological interventions advanced in FRAX and TSC are mirrored by our studies proposed here. Our studies will inform whether other forms of ID and autism potentially may share their pharmacological sensitivity and determine other potential therapeutic targets. These studies will advance the novel hypothesis that FMRP dysfunction can be seen in ID and/or autism outside of FRAX. This could impact treatment strategies for all causes of ID and/or autism. Our findings will support our hypothesis that seizures, as an external environmental factor, directly influence the development of ID and/or an autistic phenotype. These hypotheses cannot be tested in a straightforward fashion in patients. The use of our novel animal model of ELS triggering ID with an autistic phenotype allows these elusive clinical questions to be addressed more directly.