Selective Uptake of 14 C2-Deoxyglucose by Neurons and Astrocytes: High-Resolution Microautoradiographic Imaging by Cellular 14 C-Trajectography Combined with Immunohistochemistry

At the moment, there is no direct in vivo evidence of the relative amount of glucose taken up and metabolized by glial cells and neurons, respectively. Therefore, we developed a specific high cellular resolution beta-trajectory approach that allows recording and identification of individual tracks of electrons emitted during disintegrations of 14C. We used 14C2-deoxyglucose (2DG), which is an analog of glucose and is not metabolized further than the first phosphorylation by hexokinase; this property allows localization of the tracer within the cell type where it is phosphorylated. The present technical approach associated a method of cellular trajectography mainly characterized by the high thickness of the emulsion (15 microm), which permits following of the trajectory of individual electrons. This technique was improved to preserve the in vivo label of diffusible compounds such as 2DG and 2DG-6P and associated with immunohistochemical detection of neurons and astrocytes. beta-Track counting of labeled compounds was performed in 5 microm glial fibrillary acidic protein (GFAP)- and microtubule-associated protein (MAP)2-immunolabeled paraffin adjacent sections. Of 3,075 counted beta-tracks, 53.0% were localized in astrocytes on GFAP-labeled sections and 60.1% in neurons on MAP2-labeled sections. These data represent the first in vivo evidence of the compartmentation of uptake and metabolism of glucose in neurons and astrocytes.