NMR STUDIES OF GABA METABOLISM AND REGULATION IN VIVO

描述：（申请人摘要）γ-氨基丁酸（GABA）是 哺乳动物大脑皮层中主要的抑制性神经递质。 大量工作 在动物中的研究表明，GABA代谢的变化起着重要作用， 在癫痫发作活动的起源和传播中。 该项目将以 GABA合成关键酶对通量酶促调控 （谷氨酸脱羧酶，GAD）和降解（GABA-转氨酶） 用氨己烯酸（γ-乙烯基-GABA）处理的大鼠皮层， 特异性GABA-转氨酶抑制剂和最有前途的新的 临床开发中的抗癫痫药物。 我们的假设是 大脑皮层GABA合成速率的变化， 体内GABA浓度增加可以定量解释为 GABA诱导的同种型组成和活性变化的术语 GAD。 此外，GABA代谢的抑制中断了碳和氮 神经元和神经胶质之间的循环，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 皮质GABA合成的体内速率之间的关系 浓度和GAD活性（即，总GAD和主要GAD亚型） 在急性和长期GABA升高后，2）确定在 癫痫发作期间皮质GABA合成和GAD活性的体内速率和3） 对躯体感觉皮层刺激的反应。 4)确定 GABA周转率变化之间的关系， 脑组织在体内和GABA的细胞外液在急性和 慢性GABA-转氨酶抑制。 使用体内NMR光谱， 磁共振成像，体内微透析，免疫学和酶学 在体外试验中，我们将研究GABA a和其他调节剂在 GABA合成的控制和体内GABA水平的调节。 这个项目的独特性来自于1）结合的方法， 体内和体外技术，2）研究者在 使用核磁共振解决问题，以及3）这个项目 补充了正在进行的GABA和谷氨酸代谢的临床研究 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.