Molecular mechanisms linking early life seizures, autism and intellectual disabil

描述(由申请人提供)：我们试图最终了解三个基本问题：(1)早期癫痫(ELs)是否会引发具有自闭症表型的智能障碍(ID)？(2)ELs触发的信号程序可能支持这种表型？(3)哪些合理的长期药物治疗可以改善突触可塑性和体内表型的异常？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，如伴有FMRP功能障碍的脆性X(FRAX)和伴有mTOR功能障碍的结节性硬化症(TSC)。我们提出了三个具体的目标，利用电生理、生化、免疫细胞化学和行为研究。这些研究将使用成年大鼠在出生后第7天使用单一红藻氨酸诱导的ELS。这些研究将进一步探讨电生理学测量的mGluR-LTD改变的机制，并测试ELS导致类似于其他遗传形式的自闭症的表型的假设。将与年龄匹配的注射生理盐水的对照组进行比较。具体目标1：确定ELS后观察到的增强的mGluR依赖LTD的机制。这将检验这样一种假设，即mGluR依赖的LTD在ELS之后发生改变，类似于由基因中断的FMRP表达介导的改变，并且可以以类似的方式进行药理学修改。具体目标2：研究ELS后与S6激酶(SK1)高激活相关的信号通路。这将检验一种假设，即信号通路在ELS之后以类似于FMRP表达中断和过度活跃的mTOR介导的方式改变，分别在FRAX和TSC中。具体目标3：进一步表征ELS后的行为和活体表型。这将检验这样一种假设，即超越异常恐惧条件反射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后增强型LTD的药理调节剂，我们将确定这种可塑性变化是否与FRAX和TSC相关的关键特征相同。在FRAX和TSC中先进的药理干预措施反映了我们在这里提出的研究。我们的研究将告知其他形式的ID和自闭症是否可能具有相同的药理敏感性，并确定其他潜在的治疗靶点。这些研究将提出一个新的假设，即FMRP功能障碍可见于FRAX以外的ID和/或自闭症患者。这可能会影响ID和/或自闭症的所有原因的治疗策略。我们的发现将支持我们的假设，即癫痫作为一个外部环境因素，直接影响ID和/或自闭症表型的发展。这些假说不能在患者身上以直接的方式进行检验。使用我们的ELS触发具有自闭症表型的ID的新型动物模型，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.