NMR AND SPECT STUDIES OF GABA METABOLISM AND RECEPTOR DENSITY

癫痫发作是一种常见的神经系统问题。一些调查人员已经 试图更好地理解与疾病相关的病理神经化学 癫痫脑组织的体内外核磁学研究 癫痫动物模型和患者的共振波谱研究 患有癫痫。活体NMRS无法评估的问题之一是 大脑的细胞和亚细胞的异质性。光谱学 成像不能区分神经元、星形胶质细胞和 少突胶质细胞直接位于敏感体积内。分离 脑组织分化为突触神经末梢(突触体)、神经元 细胞体(神经体)和星形胶质细胞(胶质小体)是一种方法 应该能在细胞水平上洞察神经化学的异质性。 对突触体的NMRS研究可以提供对观察到的变化的洞察 活体研究。对这类制剂的NMRS研究具有相同的特征 这使得这种测量在体内是独一无二的-化学特异性和 重复性不受组织干扰的限制-但除此之外，它们 可以在完全控制细胞外空间的情况下完成 最强大的光谱仪的灵敏度和分辨率。 这个项目的总体目标是研究大脑新陈代谢 新鲜制备的大鼠突触体静息和刺激后的变化 大脑和人类大脑皮层。这项研究将集中于确定这些变化 在碳水化合物、有机酸和氨基酸的代谢这两个部分 用~1H和~(13)C核磁共振仪对神经元进行检测。具体来说，方法将是 开发用于测量13C掺入和稳定分数的速率 富含乳酸、丙氨酸、天冬氨酸、谷氨酸、谷氨酰胺、GABA、 琥珀酸和醋酸酯。~(13)C标记模式的测量 这些代谢物将提供有关标记物流动的信息 通过糖酵解、脱水、三羧酸循环，“GABA” 分流“和戊糖循环路径。

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.