MODELING COMPARTMENTATION IN THE BRAIN

大脑分区建模

• 批准号: 7600864
• 负责人: Pierre-Gilles Henry
• 金额: $ 1.51万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-01 至 2008-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7600864
• 关键词: Acetates; Amino Acids; Aspartate; Astrocytes; Back; Brain; Carbon; Citric Acid Cycle; Collaborations; Complex; Computer Retrieval of Information on Scientific Projects Database; Data; Detection; Ensure; Funding; Glucose; Glutamates; Glutamine; Goals; Grant; Heart; Human; Individual; Infusion procedures; Institution; Invasive; Label; Lead; Measurement; Measures; Mental disorders; Metabolic; Metabolism; Methods; Modeling; NMR Spectroscopy; Neurologic; Neurons; Positioning Attribute; Procedures; Rate; Rattus; Research; Research Design; Research Personnel; Resources; Source; Study models; Time; Uncertainty; United States National Institutes of Health; Work; base; brain metabolism; cell type; concept; gamma-Aminobutyric Acid; glucose metabolism; improved; in vivo; metabolic abnormality assessment; multiplet; neurotransmission; presynaptic; programs; simulation; time use; tool

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. In vivo 13C NMR spectroscopy has emerged as a unique tool to study compartmentalized brain metabolism. For example, measurements of 13C label incorporation into brain amino acids during infusion of a 13C labeled-substrate (e.g. [1-13C]glucose or [2-13C]acetate and subsequent analysis of 13C NMR time courses with a metabolic model has permitted non-invasive measurements of the TCA cycle rate and the rate of glutamate-glutamine cycle in the brain. Metabolic modeling is particularly challenging in the brain due to compartmentation of metabolism between different cell types such as neurons and astrocytes. This compartmentation has been demonstrated over 30 years ago using 14C labeled substrates and has led to the now widely accepted concept of glutamate-glutamine cycle, whereby glutamate released by presynaptic neurons is taken up by astrocytes, converted to glutamine, and sent back to neurons to resynthesize glutamate. Much progress has been done in the past ten years to develop metabolic models of compartmentalized metabolism. However, these complex models require sufficient experimental data to ensure the stability of the fitting procedure, e.g. including time courses of 13C label incorporation not only into the C4 position of glutamate and glutamine, but also the C3 and C2 positions. This additional data helps stabilize the fitting procedure and reduce uncertainty on fitted parameters. Although resolved detection of multiplets corresponding to individual isotopomers is now feasible in vivo, metabolic modeling has been traditionally performed using time courses of total 13C label at each carbon position, ignoring the additional information from multiply labeled molecules. These individual isotopomers, detected as distinct multiplets in 13C spectra, provide valuable information that could be used to improve the robustness of metabolic modeling studies. This has been demonstrated in the heart, but has not been exploited for brain studies. The goal of this collaboration is to take full advantage of the information from multiply labeled isotopomers by developing a model that can use this information. We expect that this work will lead to new metabolic modeling approaches that make optimal use of the highly specific information that can be obtained with 13C NMR and has recently become available also in vivo, ultimately increasing the robustness and precision of metabolic modeling studies in the brain. This is significant because 13C NMR measurements of brain metabolic fluxes would provide a means to directly and non-invasively measure glucose metabolism and glutamate neurotransmission in the human brain in a variety of neurological and psychiatric disorders. Preliminary data: Research Design- 1. Develop and implement a two-compartment model that includes information from 13C time courses of individual singly and multiply-labeled isotopomers. 2. Validate the new models using in vivo data obtained in the rat brain during infusion of [1,6- 13C2]glucose under different 3. Assess the reliability of the new models using Monte-Carlo simulations and compare it with the exiting model that fits total 13C label at each carbon position. Methods - The new model will be based on the most current two-compartment model for brain metabolic studies and on methods developed at UTSouthwestern to include information from individual isotopomers. This will include information from the following isotopomers that can be detected in vivo at 9.4 Tesla: (Glutamate GluC4S, GluC4D43, GluC3S, GluC3D, GluC3T, GluC2S, GluC2D23, GluC2D21, GluC2DD), Glutamine (GlnC4S, GlnC4D43, GlnC3S, GlnC3D, GlnC3T, GlnC2S, GlnC2D23, GlnC2D21, GlnC2DD). In a second step, information from aspartate and GABA isotopomers could also be included. In vivo spectra will be obtained in the rat brain during infusion of[1,6-13C2]glucose and will be quantified using the program LCModel in order to obtain time courses for multiply-labeled isotopomers.The resulting 13C time courses will be scaled to reflect actual 13C concentration using 13C NMR of brain extracts obtained at the end of the in vivo time course.

该子项目是利用该技术的众多研究子项目之一 资源由 NIH/NCRR 资助的中心拨款提供。子项目及 研究者 (PI) 可能已从 NIH 的另一个来源获得主要资金， 因此可以在其他 CRISP 条目中表示。列出的机构是 对于中心来说，它不一定是研究者的机构。 体内 13C NMR 波谱已成为研究脑区代谢的独特工具。例如，在输注 13C 标记底物（例如 [1-13C] 葡萄糖或 [2-13C] 乙酸盐）期间测量 13C 标记掺入脑氨基酸，以及随后使用代谢模型对 13C NMR 时间进程进行分析，已允许非- 大脑中 TCA 循环速率和谷氨酸-谷氨酰胺循环速率的侵入性测量由于代谢之间的划分而在大脑中特别具有挑战性。这种划分已在 30 多年前使用 14C 标记底物得到证实，并导致了现在广泛接受的谷氨酸-谷氨酰胺循环概念，即突触前神经元释放的谷氨酸被星形胶质细胞吸收并转化。过去十年中，在开发区室化代谢的代谢模型方面取得了很大进展。足够的实验数据以确保拟合过程的稳定性，例如包括13C标记不仅掺入谷氨酸和谷氨酰胺的C4位置，而且掺入C3和C2位置的时间过程。这些附加数据有助于稳定拟合过程并减少拟合参数的不确定性。尽管现在可以在体内解析检测对应于单个同位素异构体的多重峰，但传统上使用每个碳位置上总 13C 标记的时间过程进行代谢建模，忽略了来自多重标记分子的附加信息。这些单独的同位素异构体在 13C 光谱中被检测为不同的多重峰，提供了宝贵的信息，可用于提高代谢模型研究的稳健性。这已在心脏中得到证实，但尚未用于大脑研究。此次合作的目标是通过开发可以使用多重标记同位素异构体信息的模型来充分利用这些信息。我们期望这项工作将带来新的代谢建模方法，该方法能够充分利用通过 13C NMR 获得的高度特异性信息，并且最近在体内也可用，最终提高大脑代谢建模研究的稳健性和精确度。这很重要，因为大脑代谢通量的 13C NMR 测量将提供一种直接、非侵入性测量各种神经和精神疾病中人脑葡萄糖代谢和谷氨酸神经传递的方法。 初步数据：研究设计- 1. 开发并实施一个两室模型，其中包括来自各个单标记和多标记同位素异构体的 13C 时间过程的信息。 2. 使用在不同条件下输注 [1,6- 13C2] 葡萄糖期间在大鼠大脑中获得的体内数据验证新模型。 3. 使用蒙特卡罗模拟评估新模型的可靠性，并将其与现有模型进行比较。每个碳位置均适合总 13C 标签。 方法——新模型将基于用于脑代谢研究的最新两室模型以及 UTSouthwestern 开发的方法，以包含来自单个同位素异构体的信息。 这将包括可在 9.4 特斯拉体内检测到的以下同位素异构体的信息：（谷氨酸 GluC4S、GluC4D43、GluC3S、GluC3D、GluC3T、GluC2S、GluC2D23、GluC2D21、GluC2DD）、谷氨酰胺（GlnC4S、GlnC4D43、GlnC3S、 GlnC3D、GlnC3T、GlnC2S、GlnC2D23、GlnC2D21、GlnC2DD）。第二步，还可以包括天冬氨酸和 GABA 同位素异构体的信息。 [1,6-13C2]葡萄糖输注期间将在大鼠大脑中获得体内光谱，并将使用程序 LCModel 进行量化，以获得多重标记同位素异构体的时间进程。所得的 13C 时间进程将缩放至使用体内时间过程结束时获得的脑提取物的 13C NMR 反映实际 13C 浓度。