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首页> 外文期刊>Neurochemistry International: The International Journal for the Rapid Publication of Critical Reviews, Preliminary and Original Research Communications in Neurochemistry >Astrocytic energetics during excitatory neurotransmission: What are contributions of glutamate oxidation and glycolysis?
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Astrocytic energetics during excitatory neurotransmission: What are contributions of glutamate oxidation and glycolysis?

机译：兴奋性神经传递过程中的星形细胞能量学：谷氨酸的氧化和糖酵解有哪些作用？

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Astrocytic energetics of excitatory neurotransmission is controversial due to discrepant findings in different experimental systems in vitro and in vivo. The energy requirements of glutamate uptake are believed by some researchers to be satisfied by glycolysis coupled with shuttling of lactate to neurons for oxidation. However, astrocytes increase glycogenosis and oxidative metabolism during sensory stimulation in vivo, indicating that other sources of energy are used by astrocytes during brain activation. Furthermore, glutamate uptake into cultured astrocytes stimulates glutamate oxidation and oxygen consumption, and glutamate maintains respiration as well as glucose. The neurotransmitter pool of glutamate is associated with the faster component of total glutamate turnover in vivo, and use of neurotransmitter glutamate to fuel its own uptake by oxidation-competent perisynaptic processes has two advantages, substrate is supplied concomitant with demand, and glutamate spares glucose for use by neurons and astrocytes. Some, but not all, perisynaptic processes of astrocytes in adult rodent brain contain mitochondria, and oxidation of only a small fraction of the neurotransmitter glutamate taken up into these structures would be sufficient to supply the ATP required for sodium extrusion and conversion of glutamate to glutamine. Glycolysis would, however, be required in perisynaptic processes lacking oxidative capacity. Three lines of evidence indicate that critical cornerstones of the astrocyte-to-neuron lactate shuttle model are not established and normal brain does not need lactate as supplemental fuel: (i) rapid onset of hemodynamic responses to activation delivers oxygen and glucose in excess of demand, (ii) total glucose utilization greatly exceeds glucose oxidation in awake rodents during activation, indicating that the lactate generated is released, not locally oxidized, and (iii) glutamate-induced glycolysis is not a robust phenotype of all astrocyte cultures. Various metabolic pathways, including glutamate oxidation and glycolysis with lactate release, contribute to cellular energy demands of excitatory neurotransmission.
机译：由于在体外和体内不同实验系统中的发现不一致，所以兴奋性神经传递的星形细胞能量学存在争议。一些研究人员认为，通过糖酵解以及将乳酸穿梭到神经元进行氧化，可以满足谷氨酸摄取的能量需求。但是，星形胶质细胞在体内的感觉刺激过程中会增加糖原异生和氧化代谢，这表明星形胶质细胞在大脑激活过程中会使用其他能量来源。此外，谷氨酸摄取到培养的星形胶质细胞中会刺激谷氨酸氧化和耗氧，而谷氨酸可维持呼吸以及葡萄糖。谷氨酸的神经递质池与体内总谷氨酸周转速度更快的成分有关，使用神经递质谷氨酸通过具有氧化能力的突触突触过程自身摄取能量有两个优势：底物可随需求提供，谷氨酸可为葡萄糖储备葡萄糖由神经元和星形胶质细胞使用。成年啮齿动物脑中星形胶质细胞的一些但不是全部突触突触过程包含线粒体，仅将吸收到这些结构中的神经递质谷氨酸的一小部分氧化就足以提供钠挤出和谷氨酸转化为谷氨酰胺所需的ATP。 。然而，在缺乏氧化能力的突触周围过程中将需要糖酵解。三行证据表明，尚未建立星形胶质细胞至神经元乳酸穿梭模型的关键基石，并且正常大脑不需要乳酸作为补充燃料：（i）对激活的血流动力学反应迅速发作会释放过量的氧气和葡萄糖，（ii）活化过程中清醒的啮齿动物的总葡萄糖利用率大大超过了葡萄糖的氧化，表明释放出的乳酸没有被局部氧化，并且（iii）谷氨酸诱导的糖酵解不是所有星形胶质细胞培养物的强健表型。各种代谢途径，包括谷氨酸氧化和释放乳酸的糖酵解，都对兴奋性神经传递的细胞能量需求做出贡献。

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