NMR AND SPECT STUDIES OF GABA METABOLISM AND RECEPTOR DENSITY

癫痫发作是一种常见的神经问题。 一些调查人员已经 试图更好地理解与脑损伤相关的病理性神经化学， 癫痫脑组织的体外和体内核磁共振成像 在癫痫发作动物模型和患者中的共振波谱（NMRS） 患有癫痫 体内NMRS无法评估的问题之一涉及 大脑的细胞和亚细胞异质性。 光谱 成像不能区分神经元，星形胶质细胞， 少突胶质细胞直接位于敏感体积内。 分离 脑组织进入突触神经末梢（突触体），神经元 细胞体（神经小体）和星形胶质细胞（胶质小体）是一种方法， 应该能让我们深入了解细胞水平上的神经化学异质性。 突触体的NMRS研究可以为观察到的变化提供见解 体内研究。 这些制剂的核磁共振谱研究具有相同的特征 这使得这种测量在体内是独特的-化学特异性， 重复性不受组织干扰的限制-但此外， 可以通过完全控制细胞外空间来完成， 最强大的光谱仪的灵敏度和分辨率。 本项目的总体目标是研究大脑代谢， 在大鼠新鲜制备的突触体中休息和刺激后 大脑和人类皮层。 这项研究将侧重于确定 在碳水化合物、有机酸和氨基酸的代谢中， 用~ 1H和~（13）C核磁共振波谱（NMRS）对神经元进行了研究。 具体而言，方法将是 开发用于测量13 C掺入率和稳定分数 富含乳酸、丙氨酸、天冬氨酸、谷氨酸、谷氨酰胺、GABA， 琥珀酸盐和乙酸盐。 13 C标记模式的测量 这些代谢物将提供关于标记物流动的信息 通过糖酵解、回补、三羧酸循环，“GABA 分流”和戊糖循环途径。

Seizures are a common neurological problem. A number of investigators have tried to better understand the pathological neurochemistry associated with epileptic brain tissue using in vitro and in vivo nuclear magnetic resonance spectroscopy (NMRS) in animal models of seizures and in patients with epilepsy. One of the problems in vivo NMRS cannot assess concerns the cellular and sub-cellular heterogeneity of the brain. Spectroscopic imaging can not distinguish between neurons, astrocytes, and oligodendrocytes located within the sensitive volumes directly. Separating cerebral tissues into synaptic nerve terminals (synaptosomes), neuronal cell bodies (neurosomes), and astrocytes (gliosomes) is one approach which should yield insight into neurochemical heterogeneity at a cellular level. NMRS studies of synaptosomes can offer insights into the changes observed in vivo studies. NMRS studies of such preparations have the same features that make such measurements unique in vivo - chemical specificity and repeatability unlimited by disturbance of tissue - but in addition, they can be done with complete control of the extracellular space and at the sensitivity and resolution of the most powerful spectrometers available. The overall goal o this project is to investigate cerebral metabolism at rest and after stimulation in synaptosomes freshly prepared from rat cerebrum and human cortex. The study will focus on determining the changes in carbohydrate, organic acid, and amino acid metabolism in these two parts of the neuron using 1H and 13C NMRS. Specifically, methods will be developed to measure rates of 13C incorporation into and steady fractional enrichments of lactate, alanine, aspartate, glutamate, glutamine, GABA, succinate, and acetate. Measurements of the pattern of 13C-labelling of these metabolites will provide information concerning the flow of label through the glycolytic, anaplerotic, tricarboxylic acid cycle, "GABA shunt", and pentose cycle pathways.