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: 7046374
• 负责人: BRIAN David ROSS
• 金额: $ 33.44万
• 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/7046374
• 关键词: astrocytes; disease /disorder model; epilepsy; glutamate transporter; glutamates; glutamine; hippocampus; kainate; laboratory rat; magnetic resonance imaging; molecular pathology; neurons; neurotransmitter metabolism; neurotransmitter transport

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）：谷氨酸兴奋性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的代谢通量和室间转运的机制，并且2）确定谷氨酸兴奋性如何可能导致癫痫发作。 GLU在细胞外液（GLUECF）中的神经胶质吸收受损会导致过度刺激GLU受体和神经元变性（GLU兴奋性毒性毒性）。通过a）通过A）通过A）通过同型GLU进行了13C富集神经递质GLU的方法来测量神经递质GLU从细胞外液中的摄取速率和随后的代谢摄取的速率，并通过同位素的GLU选择性13C富集神经递质GLU，B）通过微质量分析和分析微质量分析，并通过对细胞外GLU收集来富集神经递质。 [5-13C，5-15N]使用局部体内13C和15N MRS形成的星形胶质细胞形成GLN。现在，使用体内15N，1H-15N HMQC和13C MRS确定，将确定GLN/GLU周期中“缺失链接”，GLN/GLU循环中的“缺失链接”。结果将阐明最近确定的GLN转运蛋白在完整的正常大脑中的作用，并确定神经胶质GLN外排（假设1）还是神经元GLN摄取（假设2）限制了体内GLN/GLU循环速率。将使用慢性海藻酸盐诱导的癫痫（KA）大鼠模型来研究颞叶癫痫中GLU释放和摄取的特定目标动力学。体内通量率将在病变和对侧海马中进行测量，并与电生理学和行为癫痫发作相关，以确定癫痫发作和癫痫发作是（假说＃3）异常GLU释放的结果（假设＃4）（假设＃4）损害GLU的过程（假设＃4）由GLIAL的过程组合（假设），或者是这些过程的组合（或者）＃5），或者是5）。这些研究共同有助于更好地了解KA中GLN/GLU周期的调节事件，并增加替代颞叶癫痫的手术管理的潜力。