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Glucose and lactate metabolism during brain activation
1Department of Neurology, Slot 500, University of Arkansas for Medical Sciences, 4301 W. Markham Street, Little Rock, AR 72205, USA. dienelgerald@uams.edu
Journal of Neuroscience Research
|December 18, 2001
Summary
Brain cells can use lactate as fuel, but the transfer between astrocytes and neurons is limited. Most lactate produced during brain activity is released externally, not trafficked internally for energy.
Area of Science:
- Neuroscience
- Cellular Metabolism
- Brain Energy Metabolism
Background:
- Brain function relies on glucose, but lactate may also serve as an energy source.
- Recent hypotheses suggest astrocytes produce lactate for neuronal use during brain activation.
- The extent of this astrocytic-neuronal lactate flux is not well understood.
Purpose of the Study:
- To evaluate the potential for astrocytic-neuronal lactate flux during brain function.
- To compare glucose utilization rates with lactate release and uptake in brain tissue and cells.
Main Methods:
- Review of existing data on glucose utilization in brain and cultured neurons/astrocytes.
- Comparison of lactate release and uptake rates in vitro and in vivo.
- Analysis of carrier-mediated lactate transport and its dependence on metabolism.
Main Results:
- Brain tissue and isolated cells release significant amounts of lactate.
- Lactate uptake is carrier-mediated and limited by intracellular metabolism.
- Lactate uptake accounts for at most 25% of glucose oxidation rate at physiological concentrations.
- Local lactate release exceeds uptake, suggesting significant overflow.
Conclusions:
- Astrocytic-neuronal lactate trafficking is likely limited, not quantitatively significant for neuronal energy supply.
- Brain activation typically results in substantial release of glycolytic lactate.
- Lactate overflow occurs to other brain areas and sometimes to blood.