PATHOPHYSIOLOGY OF DEVELOPING DYSPLASTIC HUMAN CORTEX

人类皮质发育不良的病理生理学

• 批准号: 6188291
• 负责人: GARY W. MATHERN
• 金额: $ 23.38万
• 依托单位: UNIVERSITY OF CALIFORNIA LOS ANGELES
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-07-01 至 2003-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6188291
• 关键词: AMPA receptors; GABA receptor; NMDA receptors; biocytin; brain electrical activity; child (0-11); clinical research; congenital brain disorder; developmental neurobiology; disease /disorder etiology; electrocorticography; electrophysiology; epilepsy; glutamate receptor; human subject; immunocytochemistry; in situ hybridization; kainate; neocortex; neuroanatomy; neuropathology; receptor expression

Based on neuroimaging (MRI and PET) and examination of surgically-resected tissue, cortical dysplasia (CD) has become recognized as a major pathological substrate in epilepsy. UCLA's Pediatric Epilepsy Surgery Program treats populations of children with intractable seizures, and in our experience one-half of the cases have CD while the remaining have etiologies such as strokes and encephalitis (non-CD). Very little is known about the electrophysiological properties of cells in dysplastic cortex, the underlying mechanism(s) that make CD and non-CD areas epileptogenic, and how normal postnatal cortical development affects epileptogenic neocortex. This research project is designed to address these fundamental pathophysiologic questions by performing coordinated morphologic and electrophysiologic studies on surgical tissue from these children. Our working hypothesis is that abnormal neocortex is epileptogenic because of an imbalance between excitatory and inhibitory processes and that cortical axon circuits are abnormally organized as a consequence of the pathologic process. The proposed studies will have two goals: 1) To examine the hypothesis that excitatory and inhibitory processes are altered in CD and non-CD tissue; and 2) to assess development of excitatory and inhibitory processes in neocortical neurons during human postnatal development. Each specific aim will utilize a similar experimental design incorporating pre-surgical clinical and intraoperative ECoG to determine which regions are to be studied for intracellular electrophysiology and morphologic assessments. Using state-of-the-art morphologic and electrophysiologic techniques, experiments will compare "abnormal"-appearing neurons in CD and non-CD neocortex to determine: 1) If there are differences and/or alterations in N-methyl-D-aspartate (NMDA) and non-NMDA alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) and kainate (KA)] ionotropic glutamate receptors; 2) if there are differences in the number of inhibitory neurons and/or an increase in inhibitory GABAA receptors; and 3) if one possible etiology of seizures in the tissue is from abnormal axon circuitry. These goals will be accomplished by examining in visually-identified dysplastic and normal-appearing cells: 1) The alterations in electrophysiologic membrane currents induced by activation of NMDA, AMPA, KA, and GABAA receptors; 2) the number and location of neurons expressing NMDA, non-NMDA, and GABAA subunits using in situ hybridization and immunohistochemical techniques; and 3) the dendritic and axonal connections as identified by filling recorded dysplastic neurons and normal-appearing cells with biocytin or Lucifer Yellow. The findings will provide important fundamental information necessary for the understanding of the pathophysiology of dysplastic neocortex, suggest pathologic mechanisms of intractable childhood epilepsy, and provide insights into possible ways of controlling childhood seizures resulting from CD and non-CD.

根据神经影像学（MRI 和 PET）和手术切除组织的检查，皮质发育不良（CD）已被认为是癫痫的主要病理基础。 加州大学洛杉矶分校的小儿癫痫手术项目治疗顽固性癫痫发作的儿童群体，根据我们的经验，一半的病例患有 CD，而其余病例则有中风和脑炎（非 CD）等病因。 关于发育不良皮质中细胞的电生理特性、CD和非CD区域致癫痫的潜在机制，以及正常的出生后皮质发育如何影响致癫痫新皮质，人们知之甚少。 该研究项目旨在通过对这些儿童的手术组织进行协调的形态学和电生理学研究来解决这些基本的病理生理学问题。 我们的工作假设是，异常的新皮质由于兴奋性和抑制性过程之间的不平衡而导致癫痫，并且皮质轴突回路由于病理过程而组织异常。 拟议的研究将有两个目标：1）检验 CD 和非 CD 组织中兴奋和抑制过程发生改变的假设； 2）评估人类出生后发育过程中新皮质神经元兴奋和抑制过程的发展。 每个具体目标将利用类似的实验设计，结合术前临床和术中 ECoG 来确定要研究哪些区域以进行细胞内电生理学和形态学评估。 使用最先进的形态学和电生理学技术，实验将比较 CD 和非 CD 新皮质中出现“异常”的神经元，以确定：1) N-甲基-D-天冬氨酸是否存在差异和/或改变(NMDA)和非NMDAα-氨基-3-羟基-5-甲基-4-异恶唑丙酸(AMPA)和红藻氨酸(KA)]离子型谷氨酸受体； 2) 抑制性神经元数量是否存在差异和/或抑制性 GABAA 受体增加； 3) 组织中癫痫发作的一种可能病因是否来自轴突回路异常。 这些目标将通过检查视觉识别的发育不良和正常外观的细胞来实现：1) NMDA、AMPA、KA 和 GABAA 受体激活引起的电生理膜电流的变化； 2) 使用原位杂交和免疫组织化学技术确定表达 NMDA、非 NMDA 和 GABAA 亚基的神经元的数量和位置； 3) 通过用生物胞素或荧光黄填充记录的发育不良神经元和外观正常的细胞来识别树突和轴突连接。 这些发现将为理解发育不良新皮质的病理生理学提供必要的重要基础信息，提出难治性儿童癫痫的病理机制，并为控制 CD 和非 CD 引起的儿童癫痫发作的可能方法提供见解。