Moussa Charbel E-H, Rae Caroline, Bubb William A, Griffin Julian L, Deters Natasha A, Balcar Vladimir J
Anatomy and Histology, Institute for Biomedical Research, School of Medical Science, Sydney, Australia.
J Neurosci Res. 2007 Feb 1;85(2):342-50. doi: 10.1002/jnr.21108.
High affinity uptake of glutamate plays a major role in the termination of excitatory neurotransmission. Identification of the ramifications of transporter function is essential to understand the diseases in which defective excitatory amino acid transporters (EAAT) have been implicated. In this work we incubated Guinea pig cortical tissue slices with [3-(13)C]pyruvate and major currently available glutamate uptake inhibitors and studied the resultant metabolic sequelae by (13)C and (1)H NMR spectroscopy using a multivariate statistical approach. Perturbation of glutamate uptake produced significant effects on metabolic flux through the Krebs cycle, and on glutamate/glutamine cycling rates, with this effect accounting for 76% of the variation in the total data set. The effects of all inhibitors were separable from each other along three major principal components. The competitive inhibitor L-CCG III ((2S,1'S,2'R)-2-carboxycyclopropyl)glycine) differed most from the other inhibitors, showing negative weightings on both the first and second principal components, whereas the EAAT2-specific inhibitor dihydrokainate (DHK) showed metabolic patterns similar to that of anti-endo-3,4-methanopyrolidine dicarboxylate but separate from those of DL-threo-beta-benzyloxyaspartate (TBOA) and L-trans-pyrrolidine-2,4-dicarboxylate (L-tPDC). This indicates that different inhibition mechanisms or different colocalisation of the separate transporter subtypes with glutamate receptors can produce significantly different metabolic and functional outcomes for the brain.
谷氨酸的高亲和力摄取在兴奋性神经传递的终止中起主要作用。确定转运体功能的影响对于理解与兴奋性氨基酸转运体（EAAT）缺陷有关的疾病至关重要。在这项工作中，我们用[3-(13)C]丙酮酸和目前主要可用的谷氨酸摄取抑制剂孵育豚鼠皮质组织切片，并使用多变量统计方法通过(13)C和(1)H NMR光谱研究由此产生的代谢后果。谷氨酸摄取的扰动对通过三羧酸循环的代谢通量以及谷氨酸/谷氨酰胺循环速率产生了显著影响，这种影响占整个数据集变化的76%。所有抑制剂的作用沿着三个主要主成分彼此可分离。竞争性抑制剂L-CCG III（(2S,1'S,2'R)-2-羧基环丙基）甘氨酸）与其他抑制剂差异最大，在第一和第二主成分上均显示负权重，而EAAT2特异性抑制剂二氢海因酸（DHK）显示出与抗内消旋-3,4-甲吡咯烷二羧酸酯相似的代谢模式，但与DL-苏式-β-苄氧基天冬氨酸（TBOA）和L-反式吡咯烷-2,4-二羧酸（L-tPDC）的代谢模式不同。这表明不同的抑制机制或不同的转运体亚型与谷氨酸受体的共定位可对大脑产生显著不同的代谢和功能结果。
