ABSTRACT
Recent in vitro approaches led to the hypothesis that glucose entering the brain is taken up by glial cells, metabolized to lactate which is then transferred to neurons where it would be fully oxidized. At the moment, there is no direct in vivo evidence of this type of metabolic compartmentation of energy supply to glial cells and neurons. Therefore, we developed a specific high cellular resolution [14C]2-deoxyglucose (2DG) β-trajectory approach which allows to record and identify individual tracks of electrons emitted during disintegrations of 14C. 2DG is an analog of glucose which is not metabolized further than the first phosphorylation of glycolysis. The procedure associates an improved method to preserve the in vivo label of diffusible compounds, and immunohistochemical detection of neurons and astrocytes. To assess the respective percentage of labeled astrocytes or neurons, β-track counting of labeled GFAP- and MAP2-positive cells in 5 µm paraffin adjacent sections was performed in hippocampus on 14C cellular trajectographs. Out of a total of 2156 tracks, about 50% of the β tracks were localized in astrocytes and the other 50% in neurons. These data are in good accordance with the presence of a specific transporter on neurons and its regulation by nutritional factors.