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Brain energy metabolism measured by 13 C magnetic resonance spectroscopy in vivo upon infusion of [3‐ 13 C ]lactate
Author(s) -
Duarte João M.N.,
Girault FreyaMerret,
Gruetter Rolf
Publication year - 2015
Publication title -
journal of neuroscience research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.72
H-Index - 160
eISSN - 1097-4547
pISSN - 0360-4012
DOI - 10.1002/jnr.23531
Subject(s) - glutamine , glutamate receptor , glycolysis , metabolism , pyruvate carboxylase , biochemistry , chemistry , biology , biophysics , amino acid , enzyme , receptor
The brain uses lactate produced by glycolysis as an energy source. How lactate originated from the blood stream is used to fuel brain metabolism is not clear. The current study measures brain metabolic fluxes and estimates the amount of pyruvate that becomes labeled in glial and neuronal compartments upon infusion of [3‐ 13 C]lactate. For that, labeling incorporation into carbons of glutamate and glutamine was measured by 13 C magnetic resonance spectroscopy at 14.1 T and analyzed with a two‐compartment model of brain metabolism to estimate rates of mitochondrial oxidation, glial pyruvate carboxylation, and the glutamate–glutamine cycle as well as pyruvate fractional enrichments. Extracerebral lactate at supraphysiological levels contributes at least two‐fold more to replenish the neuronal than the glial pyruvate pools. The rates of mitochondrial oxidation in neurons and glia, pyruvate carboxylase, and glutamate–glutamine cycles were similar to those estimated by administration of 13 C‐enriched glucose, the main fuel of brain energy metabolism. These results are in agreement with primary utilization of exogenous lactate in neurons rather than astrocytes. © 2014 Wiley Periodicals, Inc.