Figure 3: Quantitative comparison of neuronal and astrocytic uptake of 2DG-IR.

(a) Diagram illustrating entry of 2DG-IR into the brain via peri-arterial routes following CSF injection in GLT1-eGFP reporter mice. After 30 min circulation of 2DG-IR, the animals are perfusion fixed with 4% paraformaldehyde and 100-μm-thick vibratome sections prepared. Before imaging, the slices are washed repeatedly to remove the glucose analogue not trapped in the cytosol and the nuclei were stained with yellow-Hoechst. (b) Neurons were identified in the freshly prepared vibratome sections by their large round nuclei and the absence of cytosolic eGFP (10.2±0.7 μm diameter). Astrocytes were recognized by their smaller nuclei and eGFP signal (7.1±0.1 μm diameter, P=0.01, t-test. N=3 mice). Scale bars, 10 μm. (c) Representative images of 2DG-IR uptake by neurons and astrocytes in the cortex, striatum, CA1 and CA3 in awake GLT1-eGFP mice. Nuclei were stained with yellow-Hoechst (white). Scale bars, 20 μm. (d) Quantification of the ratio of 2DG-IR uptake in neurons versus astrocytes. P<0.001 in the cortex and striatum, P=0.002 in CA1, P=0.006 in CA3, paired t-test, neurons compared with astrocytes (N=9, 6, 8 and 7 for cortex, striatum, CA1 and CA3, respectively). Bar graphs represent mean±s.e.m.