NMR STUDIES OF GABA METABOLISM AND REGULATION IN VIVO

描述：(申请人摘要)伽玛-氨基丁酸(GABA)是 哺乳动物皮质中的主要抑制性神经递质。广泛的工作 在动物体内的研究表明，GABA代谢的变化起着重要作用 在最初的和蔓延的扣押活动中。这个项目将集中在 GABA合成关键酶对通量的酶促调控 (谷氨酸脱羧酶，GAD)和降解(GABA-转氨酶) Vigabatrin(伽马-乙烯-GABA)处理的大鼠的大脑皮层 特异性GABA转氨酶抑制剂和最有前途的新药物之一 抗癫痫药物正在临床开发中。我们的一般假设是 在长时间的运动后，大脑皮层GABA合成速率的变化 体内GABA浓度的增加可以定量地解释 GABA诱导的肌动蛋白亚型组成和活性的变化 盖德。此外，对GABA代谢的抑制也会中断碳和氮 神经元和神经胶质细胞之间的循环，改变谷氨酸和谷氨酰胺 体内代谢。我们提出了四个具体目标：1)调查 大脑皮层GABA体内合成速率与GABA的关系 浓度和GAD活性(即GAD总量和主要GAD亚型) 在急性和长期GABA升高后，2)测定血浆中 癫痫发作期间皮质GABA合成和GAD活性的活体速率和3) 对躯体感觉皮质的刺激作出反应。4)确定 年测定的GABA周转率变化之间的关系 急性期和急性期活体脑组织和细胞外液中GABA的变化 慢性GABA转氨酶抑制。使用活体核磁共振波谱， 磁共振成像、体内微透析、免疫学和酶学 在体外实验中，我们将检测GABA和其他调节剂在 体内GABA合成的控制和GABA水平的调节。 这个项目的独特性来自于1)结合的方法 活体和体外技术，2)研究人员在 使用核磁共振解决问题，以及3)该项目 补充正在进行的GABA和谷氨酸代谢的临床研究 癫痫的发病机制及抗癫痫药物对代谢的影响 人类大脑的路径。

DESCRIPTION: (Applicant's abstract) Gamma-Aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the mammalian cortex. Extensive work in animals has shown that changes in GABA metabolism plays an important role in the original and spread of seizure activity. This project will center on the enzymatic control of flux through key enzymes of GABA synthesis (glutamic acid decarboxylase, GAD) and degradation (GABA-transaminase) in the cortex of rats treated with vigabatrin (gamma-vinyl-GABA), a highly specific GABA-transaminase inhibitor and one of the most promising new anti-epileptic drugs under clinical development. Our general hypothesis is that changes in the rate of cortical GABA synthesis following a prolonged increase in GABA concentration in vivo can be interpreted quantitatively in terms of GABA-induced changes in the isoform composition and activity of GAD. Also that inhibition of GABA metabolism interrupts carbon and nitrogen cycling between neurons and glia, altering glutamate and glutamine metabolism in vivo. We propose four specific aims: 1) Investigate the relationship between the in vivo rate of cortical GABA synthesis, GABA concentration and GAD activity (i.e., total GAD and major GAD isoforms) after acute and prolonged GABA elevation, 2) Determine the changes in the in vivo rate of cortical GABA synthesis and GAD activity during seizures and 3) in response to stimulation of the somatosensory cortex. 4) Determine the relationship between the changes in the rate of turnover of GABA measured in brain tissue in vivo and GABA in the extracellular fluid during acute and chronic GABA-transaminase inhibition. Using in vivo NMR Spectroscopy, Magnetic Resonance Imaging, in vivo microdialysis, immunologic and enzymatic assays in vitro, we will examine the role of GABa and other modulators in the control of GABA synthesis and the regulation of GABA levels in vivo. The uniqueness of this project derives from 1) the approach of combining in vivo and in vitro techniques, 2) the track record of the investigators in addressing questions using NMR, and 3) the fact that this project complements ongoing clinical investigations of GABA and glutamate metabolism in epilepsy and the effects of antiepileptic medications on the metabolic pathways of the human brain.