The metabolism of [3-(13)C]lactate in the rat brain is specific of a pyruvate carboxylase-deprived compartment

J Neurochem. 2000 Aug;75(2):480-6. doi: 10.1046/j.1471-4159.2000.0750480.x.


Lactate metabolism in the adult rat brain was investigated in relation with the concept of lactate trafficking between astrocytes and neurons. Wistar rats were infused intravenously with a solution containing either [3-(13)C]lactate (534 mM) or both glucose (750 mM) and [3-(13)C]lactate (534 mM). The time courses of both the concentration and (13)C enrichment of blood glucose and lactate were determined. The data indicated the occurrence of [3-(13)C]lactate recycling through liver gluconeogenesis. The yield of glucose labeling was, however, reduced when using the glucose-containing infusate. After a 20-min or 1-h infusion, perchloric acid extracts of the brain tissue were prepared and subsequently analyzed by (13)C- and (1)H-observed/(13)C-edited NMR spectroscopy. The (13)C labeling of amino acids indicated that [3-(13)C]lactate was metabolized in the brain. Based on the alanine C3 enrichment, lactate contribution to brain metabolism amounted to 35% under the most favorable conditions used. By contrast with what happens with [1-(13)C]glucose metabolism, no difference in glutamine C2 and C3 labeling was evidenced, indicating that lactate was metabolized in a compartment deprived of pyruvate carboxylase activity. This result confirms, for the first time from an in vivo study, that lactate is more specifically a neuronal substrate.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Astrocytes / metabolism*
  • Blood Glucose / metabolism
  • Brain / metabolism*
  • Carbon Isotopes
  • Female
  • Gluconeogenesis
  • Kinetics
  • Lactates / blood
  • Lactates / metabolism*
  • Liver / metabolism
  • Magnetic Resonance Spectroscopy / methods
  • Neurons / metabolism*
  • Pyruvate Carboxylase / metabolism
  • Rats
  • Rats, Wistar


  • Blood Glucose
  • Carbon Isotopes
  • Lactates
  • Pyruvate Carboxylase