Patel A J, Hunt A, Gordon R D, Balázs R
Brain Res. 1982 May;256(1):3-11. doi: 10.1016/0165-3806(82)90091-8.
The cellular distribution of certain enzymes associated with the metabolic compartmentation of glutamate was estimated in ultrastructurally preserved and metabolically competent perikarya fractions that were enriched in astrocytes, granule cells and Purkinje cells and derived from 8-day-old rat cerebellum, and in monolayer cultures (14 days in vitro) composed principally of interneurones or astrocytes. The neuronal activities of glutamine synthetase and glutamate dehydrogenase were respectively about 4- to 8-fold and 2- to 5-fold lower than in astrocytes, depending upon the class of neurone and the type of preparation used for comparison. By contrast glutaminase activity was about 3- to 12-fold higher in neuronal than in astroglial preparations. Estimations of the specific activity of succinate dehydrogenase differed less between cell types, indicating that the differences in glutamate dehydrogenase and glutaminase were not simply related to variations in the concentration of mitochondria relative to the other cellular constituents. The findings presented provide direct evidence in support of our model assigning the 'small' glutamate compartment, where most of the labelled glutamine is synthesized, to glial cells, and the 'large' compartment to neurones, and also underline the metabolic interaction between these two cell types in the brain.
在超微结构保存完好且代谢功能正常的核周体组分中，对与谷氨酸代谢区室化相关的某些酶的细胞分布进行了评估。这些核周体组分富含星形胶质细胞、颗粒细胞和浦肯野细胞，取自8日龄大鼠的小脑，同时也在主要由中间神经元或星形胶质细胞组成的单层培养物（体外培养14天）中进行了评估。谷氨酰胺合成酶和谷氨酸脱氢酶的神经元活性分别比星形胶质细胞低约4至8倍和2至5倍，这取决于所比较的神经元类别和制备类型。相比之下，谷氨酰胺酶活性在神经元制剂中比在星形胶质细胞制剂中高约3至12倍。琥珀酸脱氢酶比活性的估计在不同细胞类型之间差异较小，这表明谷氨酸脱氢酶和谷氨酰胺酶的差异并非仅仅与线粒体相对于其他细胞成分的浓度变化有关。所呈现的研究结果为我们的模型提供了直接证据，该模型将大部分标记谷氨酰胺合成所在的“小”谷氨酸区室归为神经胶质细胞，将“大”区室归为神经元，同时也强调了这两种细胞类型在大脑中的代谢相互作用。
