Premium
Competition between glucose and lactate as oxidative energy substrates in both neurons and astrocytes: a comparative NMR study
Author(s) -
BouzierSore AnneKarine,
Voisin Pierre,
Bouchaud Véronique,
Bezancon Eric,
Franconi JeanMichel,
Pellerin Luc
Publication year - 2006
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/j.1460-9568.2006.05056.x
Subject(s) - glutamine , glycolysis , biochemistry , metabolism , oxidative phosphorylation , carbohydrate metabolism , alanine , glutamate receptor , biology , astrocyte , glucose uptake , glycogen , chemistry , amino acid , endocrinology , central nervous system , receptor , insulin
Competition between glucose and lactate as oxidative energy substrates was investigated in both primary cultures of astrocytes and neurons using physiological concentrations (1.1 m m for each). Glucose metabolism was distinguished from lactate metabolism by using alternatively labelled substrates in the medium ([1‐ 13 C]glucose + lactate or glucose + [3‐ 13 C]lactate). After 4 h of incubation, 1 H and 13 C‐NMR spectra were realized on perchloric acid extracts of both cells and culture media. For astrocytic cultures, spectra showed that amino acids (glutamine and alanine) were more labelled in the glucose‐labelled condition, indicating that glucose is a better substrate to support oxidative metabolism in these cells. The opposite was observed on spectra from neuronal cultures, glutamate being much more labelled in the lactate‐labelled condition, confirming that neurons consume lactate preferentially as an oxidative energy substrate. Analysis of glutamine and glutamate peaks (singlets or multiplets) also suggests that astrocytes have a less active oxidative metabolism than neurons. In contrast, they exhibit a stronger glycolytic metabolism than neurons as indicated by their high lactate production yield. Using a mathematical model, we have estimated the relative contribution of exogenous glucose and lactate to neuronal oxidative metabolism. Under the aforementioned conditions, it represents 25% for glucose and 75% for lactate. Altogether, these results obtained on separate astrocytic and neuronal cultures support the idea that lactate, predominantly produced by astrocytes, is used as a supplementary fuel by neurons in vivo already under resting physiological conditions.