NMR Studies of GABA Metabolism and Regulation in Vivo

描述：(逐字摘自申请人的摘要)在过去的10-15年里，我们的实验室在新技术的开发和使用方面发挥了重要作用 体内光谱和成像技术研究信号转导途径的调控 大脑的葡萄糖新陈代谢。在这笔赠款的过去4年里，我们报告了 一些重要的发现表明谷氨酸和GABA的释放 来自神经元及其在神经元和神经胶质细胞之间的循环具有重大影响 脑能量代谢及GABA关键酶的亚型 合成谷氨酸脱羧酶(GAD)介导不同比例的 GABA总合成量。我们的中心假设是特定的GAD亚型和 谷氨酸碳的供应途径在调节GABA合成中起关键作用 和GABA神经递质循环。我们提出了以下具体目标：1) 测定GABA合成率与GABA合成率的关系 神经递质循环和谷氨酸/谷氨酰胺循环在广泛的 皮质代谢活动。1b)评估辅因相互作用的作用和 GAD亚型在调节GABA合成和调节中的磷酸化 GABA/谷氨酰胺循环通量。2)研究GAD异构体在 两条谷氨酸前体途径对GABA循环通量的调节 应用GABA转氨酶抑制和GABA升高选择性改变GAD 异构体组成。3)量化提供的关键代谢途径通量 谷氨酸前体参与GABA合成和GABA/谷氨酰胺循环。4) 确定囊泡型和非囊泡型GABA前体之间的关系 谷氨酸途径和GAD异构体在体内的扩散敏化MRS。 在体内使用磁共振波谱(MRS)和13C标记的同位素， 以及药理学和分子生物学的体外酶促检测 干预，我们将研究GAD亚型和谷氨酸的作用 GABA合成前体和GABA神经递质循环的唯一性 这个项目的价值来自于i)这些技术的结合，ii) 调查员在使用MRS解决此类问题时的记录， 和iii)它补充了正在进行的GABA和谷氨酸的临床研究 癫痫和神经精神障碍的代谢。

DESCRIPTION: (Verbatim from the Applicant's Abstract) For the last 10-15 years our laboratory has had a major role in the development and use of new spectroscopy and imaging techniques in vivo to study the regulation of pathways of brain glucose metabolism. Over the last 4 years of this grant we reported a number of important findings which indicate that release of glutamate and GABA from neurons and their cycling between neurons and glia has a major influence on brain energy metabolism and that the isoforms of a key enzyme of GABA synthesis, glutamic acid decarboxylase (GAD) mediate different proportions of total GABA synthesis. Our central hypothesis is that specific GAD isoforms and supply routes of glutamate carbon play key roles in regulating GABA synthesis and GABA neurotransmitter cycling. We propose the following specific aims: 1a) Determine the relationship between the rates of GABA synthesis, GABA neurotrasmitter cycling, and glutamate/glutamine cycle over a wide range of cortical metabolic activity. 1b) Assess the role of cofactor interaction and phosphorylation of the GAD isoforms in the regulation of GABA synthesis and GABA/glutamine cycling flux. 2) Investigate the role of GAD isoforms in regulation of GABA cycling flux through the two glutamate precursor pathways using GABA-transaminase inhibition and GABA elevation to selectively alter GAD isoform composition. 3) Quantitate the key metabolic pathway fluxes that supply glutamate precursors for GABA synthesis and GABA/glutamine cycling. 4) Determine the relationship between vesicular and non-vesicular GABA, precursor glutamate pathways, and GAD isoforms using diffusion-sensitized MRS in vivo. Using Magnetic Resonance spectroscopy (MRS) and 13C-labeled isotopes in vivo, and enzymatic assays in vitro with pharmacological and molecular biological interventions, we will examine the role of GAD isoforms and glutamate precursors in GABA synthesis and GABA neurotransmitter cycling The uniqueness of this project derives from i) the combination of the these techniques, ii) the track record of the investigator in addressing such questions using MRS, and iii) it complements ongoing clinical investigations of GABA and glutamate metabolism in epilepsy and neuropsychiatric disorders.