NMR Studies of GABA Metabolism and Regulation in Vivo

描述：（来自申请人摘要的逐字记录）过去10-15年 我们的实验室在开发和使用新的 光谱和成像技术在体内研究的调节途径 大脑葡萄糖代谢。在过去的4年里，我们报告了一个 一些重要的发现表明谷氨酸和GABA的释放 神经元和神经胶质细胞之间的循环有很大的影响 对大脑能量代谢的影响，GABA的一种关键酶的亚型 合成，谷氨酸脱羧酶（GAD）介导不同比例 总GABA合成。我们的中心假设是，特定的GAD亚型和 谷氨酸碳供应途径在调节GABA合成中起关键作用 和GABA神经递质循环。我们提出以下具体目标：1a） 确定GABA合成速率、GABA 神经递质循环和谷氨酸/谷氨酰胺循环在很宽的范围内 皮质代谢活动1b）评估辅因子相互作用的作用， 在GABA合成的调节中GAD同种型的磷酸化， GABA/谷氨酰胺循环通量。2)研究GAD亚型在 通过两种谷氨酸前体途径调节GABA循环通量 使用GABA-转氨酶抑制和GABA升高选择性改变GAD 同种型组成。3)定量供应的关键代谢途径通量 用于GABA合成和GABA/谷氨酰胺循环的谷氨酸前体。四、 确定囊泡和非囊泡GABA前体之间的关系 谷氨酸途径，和GAD亚型使用扩散敏化MRS在体内。 使用磁共振波谱（MRS）和13 C标记的同位素在体内， 药理学和分子生物学的体外酶测定 干预措施，我们将研究GAD亚型和谷氨酸的作用， GABA合成和GABA神经递质循环中的前体 该项目的起源于i）这些技术的结合，ii） 研究者使用MRS解决此类问题的跟踪记录， 和iii）它补充了正在进行的GABA和谷氨酸的临床研究 癫痫和神经精神疾病的代谢。

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.