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Effect of glutamine and GABA on [U-13C]glutamate metabolism in cerebellar astrocytes and granule neurons

Authors

  • Hong Qu,

    1. Department of Clinical Neuroscience, Norwegian University of Science and Technology, Trondheim, Norway
    2. Department of Physics, Norwegian University of Science and Technology, Trondheim, Norway
    3. MR-Center, SINTEF-UNIMED, Trondheim, Norway
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  • Jon R. Konradsen,

    1. Department of Clinical Neuroscience, Norwegian University of Science and Technology, Trondheim, Norway
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  • Marike van Hengel,

    1. Department of Clinical Neuroscience, Norwegian University of Science and Technology, Trondheim, Norway
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    • Marike van Hengel and Saskia Wolt are currently on leave from the Medical Faculty, the Vrije University of Amsterdam, Netherlands.

  • Saskia Wolt,

    1. Department of Clinical Neuroscience, Norwegian University of Science and Technology, Trondheim, Norway
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    • Marike van Hengel and Saskia Wolt are currently on leave from the Medical Faculty, the Vrije University of Amsterdam, Netherlands.

  • Ursula Sonnewald

    Corresponding author
    1. Department of Clinical Neuroscience, Norwegian University of Science and Technology, Trondheim, Norway
    • Department of Clinical Neuroscience, Faculty of Medicine, Olav Kyrresgt. 3, N-7489 Trondheim, Norway
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Abstract

To probe the effect of glutamine and GABA on metabolism of [U-13C]glutamate, cerebellar astrocytes were incubated with [U-13C]glutamate (0.5 mM) in the presence and absence of glutamine (2.5 mM) or GABA (0.2 mM). It could be shown that consumption of [U-13C]glutamate was decreased in the presence of glutamine and release of labeled aspartate and [1,2,3-13C]glutamate decreased as well, whereas the concentrations of these metabolites increased inside the cells. Glutamine decreased energy production from [U-13C]glutamate presumably by substituting for glutamate as an energy substrate. No additional effect was seen in the presence of both glutamine and GABA. When cerebellar granule neurons were incubated with [U-13C]glutamate (0.25 mM) and GABA (0.05 mM), less [U-13C]glutamate was used for energy production than in controls. Because the barbiturate thiopental did not elicit such response (Qu et al., 2000, Neurochem Int 37:207–215) it appears that GABA also has a metabolic function in the glutamatergic cerebellar granule neurons in contrast to the astrocytes. © 2001 Wiley-Liss, Inc.

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