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

谷氨酸控制癫痫的 13C 和 15N MRS 研究

• 批准号: 7162115
• 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
• 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/7162115
• 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

DESCRIPTION (provided by applicant): 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.

描述（由申请人提供）：谷氨酸兴奋毒性与癫痫发作有关。我们的目标是 1) 阐明控制完整哺乳动物大脑中谷氨酸和谷氨酰胺代谢流和区室间运输的机制，2) 确定谷氨酸兴奋性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 GLU 受体过度刺激和神经元变性（GLU 兴奋性毒性）。神经递质 GLU 从细胞外液摄取到星形胶质细胞以及随后代谢为 GLN 的速率通过 a) 通过同位素追踪对神经递质 GLU 进行选择性 13 C 富集，b) 通过微透析收集细胞外 GLU 并通过气相色谱/质谱分析其 13 C 富集，以及 c) 观察 [5-13C, 5-15N] GLN 使用局部体内 13C 和 15N MRS 在星形胶质细胞中形成。现在，具体目标#1，GLN/GLU 循环中的“缺失环节”，GLN 从星形胶质细胞转运到神经元的动力学和机制将使用体内 15N、1H-15N HMQC 和 13C MRS 来确定。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，并确定神经胶质 GLN 流出速率（假设 1）或神经元 GLN 摄取速率（假设 2）是否限制体内 GLN/GLU 循环速率。具体目标#2 将使用慢性红藻氨酸诱导的癫痫 (KA) 大鼠模型研究颞叶癫痫中 GLU 释放和摄取的动力学。将测量病变海马和对侧海马的体内通量率，并将其与电生理学和行为癫痫发作相关联，以确定癫痫发作的发作和传播是否是（假设＃3）异常GLU释放，（假设＃4）神经胶质转运蛋白GLU清除受损，或（假设＃5）这些过程的组合的结果。这些研究将有助于更好地了解 KA 中 GLN/GLU 循环的调节事件，并增加替代颞叶癫痫手术治疗的潜力。