Astrocytes are poised for lactate trafficking and release from activated brain and for supply of glucose to neurons
Article first published online: 13 AUG 2009
© 2009 The Authors. Journal Compilation © 2009 International Society for Neurochemistry
Journal of Neurochemistry
Volume 111, Issue 2, pages 522–536, October 2009
How to Cite
Gandhi, G. K., Cruz, N. F., Ball, K. K. and Dienel, G. A. (2009), Astrocytes are poised for lactate trafficking and release from activated brain and for supply of glucose to neurons. Journal of Neurochemistry, 111: 522–536. doi: 10.1111/j.1471-4159.2009.06333.x
- Issue published online: 23 SEP 2009
- Article first published online: 13 AUG 2009
- Received June 17, 2009; revised manuscript received/accepted August 7, 2009.
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Brain is a highly-oxidative organ, but during activation, glycolytic flux is preferentially up-regulated even though oxygen supply is adequate. The biochemical and cellular basis of metabolic changes during brain activation and the fate of lactate produced within brain are important, unresolved issues central to understanding brain function, brain images, and spectroscopic data. Because in vivo brain imaging studies reveal rapid efflux of labeled glucose metabolites during activation, lactate trafficking among astrocytes and between astrocytes and neurons was examined after devising specific, real-time, sensitive enzymatic fluorescent assays to measure lactate and glucose levels in single cells in adult rat brain slices. Astrocytes have a 2- to 4-fold faster and higher capacity for lactate uptake from extracellular fluid and for lactate dispersal via the astrocytic syncytium compared to neuronal lactate uptake from extracellular fluid or shuttling of lactate to neurons from neighboring astrocytes. Astrocytes can also supply glucose to neurons as well as glucose can be taken up by neurons from extracellular fluid. Astrocytic networks can provide neuronal fuel and quickly remove lactate from activated glycolytic domains, and the lactate can be dispersed widely throughout the syncytium to endfeet along the vasculature for release to blood or other brain regions via perivascular fluid flow.