Olivocerebellar Circuitry in Autism

自闭症是一种发育障碍，患者的大脑功能会发生改变，从而破坏他们执行特定运动和认知任务的能力。该项目的主要长期目标是确定在一个主要受影响的大脑区域，小脑，突触水平上的连接变化是如何基于关键传入投射和目标神经元早期发育中的错误而受到干扰的。Glutamatergic苔藓纤维,olivocerebellar爬纤维和纤维平行所有关键小脑皮质神经元突触,其中一些显示孤独症的神经病理变化。本研究的主要目的集中在小脑皮层两个功能不同部分的关键谷氨酸转运体和受体，后叶的小腿II区最近与认知功能有关，前叶的蚓小叶VI对感觉运动的作用很重要。定量谷氨酸能测量将与自闭症诊断访谈-修订（ADI-R）中互惠社会互动、沟通、刻板印象和重复运动行为领域的得分相关。为了实现这些目标，在10个成年（16-30岁）死后自闭症病例和10个年龄、性别和死后间隔匹配的对照中提出了四个具体目标。第一个具体目标将在第一年完成，使用组织学配体结合来确定小脑传入事件靶点II足部和VI小叶三个层中的关键嗜离子性受体（AMPAR， NMDAR）和代谢性谷氨酸受体（mGluR1）的数量和配体结合亲和力。第二个具体目标，将在第一年完成，在相同的小脑区域使用原位杂交组织化学来量化三种突触后谷氨酸受体亚型（AMPAR1， NMDAR1和mGluR1）的mRNA水平。第三个具体目标是在第一年进行试验，并在第二年完成，量化在pc末端的关键谷氨酸转运体的密度(Le。兴奋性氨基酸转运蛋白4型，EAAT4；主要包裹在攀登突触周围的伯格曼神经胶质膜上（EAA T1， l -谷氨酸/ l -天冬氨酸转运体，GLAST）；谷氨酸受体（GluRo2）在诱导长期抑郁（LTD）中起重要作用，主要定位于pc上的平行纤维突触。GluRo2与PSD93共定位将决定突触后密度的百分比，EAAT4与synaptophysin共定位将决定突触前密度的百分比。最终的具体目标，将在第二年完成，采用翻译方法，评估谷氨酸受体、转运体和突触密度与自闭症诊断访谈-修订版（ADI-R）测量的社交和重复行为症状严重程度的关系。本研究旨在探讨两个功能不同的小脑区域中关键兴奋性谷氨酸成分的显著变化是否与临床病例中自闭症症状类型和严重程度有差异。在为期两年的项目中，这些研究的数据将有助于描绘自闭症患者的核心神经基质，并有助于指导遗传学家寻找这种疾病可能的候选基因。此外，了解该模型区域内的细胞和分子机制有助于我们了解当前自闭症患者的药物治疗方法，并可能提出针对神经基质的新治疗方法。

Autism is a developmental disorder and affected individuals have alterations in brain function disrupting their ability to perform particular motor and cognitive tasks. The main long term objective of this project is to determine in one major affected brain region, the cerebellum, how changes in connectivity at the synaptic level are disturbed based on errors in the early development of key afferent projections and target neurons. Glutamatergic mossy fibers, olivocerebellar climbing fibers and parallel fibers all synapse on key cerebellar cortical neurons, some of which show neuropathological changes in autism. The major objective of this study focuses on key glutamatergic transporters and receptors in two functionally distinct parts of the cerebellar cortex, the Crus II area in the posterior lobe recently implicated in cognitively-based functions and vermis lobule VI in the anterior lobe important for sensorimotor-based roles. Quantitative glutamatergic measures will be related to scores from the Autism Diagnostic Interview-Revised (ADI-R) for reciprocal social interaction, communication, and stereotyped and repetitive motor behavior domains. To accomplish these objectives, four specific aims are proposed in ten adult (age 16-30 years old) autistic post-mortem cases and ten age-, gender and postmortem interval-matched controls. The first specific aim, to be completed in the first year, uses histological ligand binding to determine the number and ligand binding affinity of key ionotropic (AMPAR, NMDAR) and metabotropic glutamate receptors (mGluR1) in the three laminae of Crus II and lobule VI, targets for cerebellar afferents. The second specific aim, to be completed in the first year, uses in situ hybridization histochemistry in the same cerebellar regions to quantify the mRNA levels of three types of postsynaptic glutamate receptor subtypes (AMPAR1, NMDAR1 and mGluR1). The third specific aim with trials in the first year and completed in the second year, quantifies the densities of key glutamate transporters at terminals ending on PCs (Le., excitatory amino acid transporter type 4, EAAT4; on membranes of Bergmann glia that predominately wrap around climbing synapses (EAA T1, L-glutamate/L-aspartate transporter, GLAST); and a glutamate receptor (GluRo2) that is important for induction of long-term depression (LTD) and is predominately localized to parallel fiber synapses on PCs. Co-localization of GluRo2 with PSD93 will determine the percentage of postsynaptic density and co-localization of EAAT4 with synaptophysin will determine the percentage of presynaptic density. The final specific aim, to be completed in the second year, takes a translational approach and evaluates the relationships of glutamate receptors, transporters and synaptic density to severity of social-communicative and repetitive behavior symptoms as measured by the Autism Diagnostic Interview - Revised (ADI-R). This aim examines whether significant changes in key excitatory glutamate component(s) in the two functionally distinct cerebellar regions relate differentially to autism symptom type and severity in the clinical cases. Data from these studies over the two year project will help delineate core neural substrates in autistic individuals and should help guide geneticists in their search for possible candidate genes in the disorder. Furthermore, understanding the cellular and molecular mechanisms within this model region could contribute to our understanding of current pharmacotherapeutic treatments of autistic individuals and may suggest novel treatments targeted to neural substrates.