Premium
13 C NMR spectroscopy study of cortical nerve cell cultures exposed to hypoxia
Author(s) -
Müller T. B.,
Sonnewald U.,
Westergaard N.,
Schousboe A.,
Petersen S. B.,
Unsgård G.
Publication year - 1994
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.490380310
Subject(s) - glutamine , citric acid cycle , tricarboxylic acid , glutamate receptor , biochemistry , chemistry , hypoxia (environmental) , nuclear magnetic resonance spectroscopy , cell culture , metabolism , biology , biophysics , oxygen , amino acid , stereochemistry , receptor , organic chemistry , genetics
Primary cultures of cerebral cortical GABA‐ergic neurons growing on top of a preformed layer of astrocytes (co‐cultures) were incubated with [1‐ 13 C]glucose and exposed to a low oxygen atmosphere (2% O 2 ) for 17 hr. 13 C, 1 H, and 13 P nuclear magnetic resonance (NMR) spectroscopy was performed on perchloric acid (PCA) extracts of cells and of media collected from these cultures. In the control groups incorporation of 13 C label into glutamine, citrate, and lactate could be demonstrated in both cell extracts and culture media. Labeled GABA and glutamate were only observed in cell extracts. During hypoxia high energy phosphates decreased but lactate production and glucose consumption increased. There was a decreased amount of citrate and glutamine in cell extracts and media of the hypoxic co‐cultures. There was a change in distribution of the 13 C label within the GABA molecule, with an increase of labeling in the C‐2 position. This change in 13 C distribution was not found in glutamine present in the media where it is a precursor for GABA in neurons. Instead a decrease in the corresponding C‐4 position was observed. These results suggest that energy depletion during hypoxia leads to reduced export from the astrocytic tricarboxylic acid (TCA) cycle as demonstrated by a decreased amount of citrate and changed distribution of 13 C in glutamine. The change in the distribution of label in GABA from cell extracts as compared to glutamine in the medium may indicate that neurons are synthesizing GABA using precursors supplied from their own TCA cycle and not from precursors supplied by astrocytes.