13C and 15N MRS Study of glutamate control in epilepsy

谷氨酸控制癫痫的 13C 和 15N MRS 研究

基本信息

批准号：
7340429
负责人：
BRIAN David ROSS
金额：
$ 32.47万
依托单位：
HUNTINGTON MEDICAL RESEARCH INSTITUTES
依托单位国家：
美国
项目类别：
财政年份：
2006
资助国家：
美国
起止时间：
2006-01-01 至 2009-12-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7340429
关键词：
Animal Model Astrocytes Behavioral Binding Brain Brain region Chronic Chronic Phase Collection Contralateral Convulsions Epilepsy Event Exocytosis Extracellular Fluid Gas Chromatography Glutamate Receptor Glutamate Transporter Glutamates Glutamine Hippocampus (Brain)Human In Situ Invasive Ipsilateral Isotopes Kinetics Laboratories Lead Lesion Link Localized Magnetic Resonance Spectroscopy Mass Fragmentography Mass Spectrum Analysis Measurement Measures Mediating Metabolic Control Metabolism Microdialysis Modeling Monitor Motor Cortex Nerve Degeneration Neuroglia Neurons Neurotransmitters Numbers Process Rate Rattus Recycling Research Personnel Role Seizures Surgical Management Synapses Temporal Lobe Epilepsy Thinking Time excitotoxicity extracellular in vivo kainate nervous system disorder neurotransmission neurotransmitter uptake novel strategies programs quantum receptor system N protein 1 uptake

项目摘要

Glutamate excitotoxicity has been implicated in epileptic seizures. Our objectives are 1) to clarify the mechanisms that control the metabolic flux and intercompartmental transport of glutamate and glutamine in the intact mammalian brain and 2) determine how glutamate excitotoxicity may cause epileptic seizures. Impaired glial uptake of GLU in the extracellular fluid (GLUECF) can lead to excessive stimulation of the GLU receptors and to neuronal degeneration (GLU excitotoxicity). The rate of uptake of neurotransmitter GLU from the extracellular fluid into astrocytes and subsequent metabolism to GLN has been measured through a) selective 13C enrichment of neurotransmitter GLU by isotope chase, b) collection of extracellular GLU by microdialysis and analysis of its 13C enrichment by gas-chromatography/mass spectrometry and c) observation of [5-13C, 5-15N] GLN formed in astrocytes using localized in vivo 13C and 15N MRS. Now, Specific Aim #1, a 'missing-link' in the GLN/GLU cycle, the kinetics and mechanism of transport of GLN from astrocytes to neurons will be determined using in vivo 15N, 1H-15N HMQC and 13C MRS. The results will clarify the roles of recently identified GLN transporters in the intact normal brain and determine whether the rate of glial GLN efflux (hypothesis #1) or of neuronal GLN uptake (hypothesis #2) limits the GLN/GLU cycle rate in vivo. Specific Aim #2 Kinetics of GLU release and uptake in temporal lobe epilepsy will be studied using the chronic kainate-induced epileptic (KA) rats model. In vivo flux rates will be measured in the lesioned and contralateral hippocampus and correlated with electrophysiological and behavioral seizures, to determine whether the onset and propogation of seizures is the result of (hypothesis #3) abnormal GLU release, (hypothesis #4) impaired GLU clearance by glial transporters, or (hypothesis #5) a combination of these processes. Together these studies will contribute to a better understanding of the regulatory events of the GLN/GLU cycle in KA and increase potential to replace surgical management of temporal lobe epilepsy.

谷氨酸兴奋毒性与癫痫发作有关。我们的目标是 1) 澄清控制谷氨酸和谷氨酰胺代谢通量和室间运输的机制完整的哺乳动物大脑；2) 确定谷氨酸兴奋毒性如何导致癫痫发作。神经胶质细胞对细胞外液中 GLU 的摄取受损 (GLUECF) 可导致过度刺激 GLU 受体和神经元变性（GLU 兴奋毒性）。神经递质的摄取率测量了 GLU 从细胞外液进入星形胶质细胞以及随后代谢为 GLN 的情况通过 a) 通过同位素追踪选择性 13C 富集神经递质 GLU，b) 收集细胞外通过微透析获得 GLU 并通过气相色谱/质谱分析其 13C 富集，以及 c) 使用局部体内 13C 和 15N MRS 观察星形胶质细胞中形成的 [5-13C, 5-15N] GLN。现在，具体目标#1，GLN/GLU 循环中的“缺失环节”，GLN 的动力学和运输机制将使用体内 15N、1H-15N HMQC 和 13C MRS 测定星形胶质细胞到神经元。结果将阐明最近发现的 GLN 转运蛋白在完整正常大脑中的作用，并确定是否神经胶质 GLN 流出率（假设 1）或神经元 GLN 摄取率（假设 2）限制 GLN/GLU 循环体内率。具体目标#2 将研究颞叶癫痫中 GLU 释放和摄取的动力学使用慢性红藻氨酸诱导的癫痫（KA）大鼠模型。体内通量率将在病变和对侧海马体并与电生理和行为癫痫发作相关，确定癫痫发作的发生和传播是否是（假设#3）异常 GLU 的结果释放，（假设 4）神经胶质转运蛋白 GLU 清除受损，或（假设 5）以下因素的组合这些过程。这些研究共同将有助于更好地理解监管事件 KA 中的 GLN/GLU 循环，并增加替代颞叶癫痫手术治疗的潜力。