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. 2021 Mar;116:154463. doi: 10.1016/j.metabol.2020.154463

Fig. 2.

Fig. 2

Noradrenaline-induced increase in cytosolic d-glucose is reduced in astrocytes from Gdi1 KO versus WT animals. a Mean time-dependent changes in cytosolic d-glucose concentration ([glucose]i), presented as changes in EYFP/ECFP fluorescence (FRET) signal in astrocytes expressing FLII12PGLU-700 μΔ6 on noradrenaline stimulation (NA, 200 μM). Experiments were performed in control (left) and in 2 mM l-lactate pre-treated (Lac) astrocytes (right), isolated from Gdi1 WT (black; 14 responsive out of 42 cells for NA, 10 responsive out of 20 cells for Lac + NA) and Gdi1 KO animals (white; 20 responsive out of 42 cells for NA, 8 responsive out of 12 cells for Lac + NA), each obtained on 3 independent cultures. Changes in the FRET signal are expressed as percentages relative to the initial values. Single exponential functions were fitted to the curves (see Supplementary Table 2 for equation parameters). b Mean amplitudes (∆FRET) and time constants (τ) of NA-induced increase in [glucose]i from Gdi1 WT and Gdi1 KO astrocytes in the absence and presence of 2 mM l-Lactate (NA and Lac + NA, respectively) determined by fitting exponential functions (see parameters in Supplementary Table2). c Mean time-dependent changes in cytosolic cAMP-dependent PKA activity presented as changes in YFP/CFP fluorescence (FRET) signal in astrocytes expressing cAMP/PKA nanosensor AKAR2 on NA stimulation (100 μM). Experiments were performed in control (left) and in 2 mM L-lactate pre-treated (Lac) astrocytes (right) isolated from Gdi1 WT (black; 12 responsive out of 12 cells [control], 11 responsive out of 11 cells [Lac]) and Gdi1 KO animals (white; 11 responsive out of 11 cells [control], 12 responsive out of 12 cells [Lac]). Cell cultures were prepared from 5 Gdi1 WT and 4 Gdi1 KO animals for NA stimulation; and 4 Gdi1 WT and 5 Gdi1 KO animals for NA stimulation on 2 mM L-lactate pre-treated astrocytes. Single exponential functions were fitted to the curves (see Supplementary Table 2 for equation format). d Mean amplitudes (∆FRET) and time constants (τ) of NA-induced increase in cAMP/PKA activity in Gdi1 WT and Gdi1 KO astrocytes in the absence and presence of pre-treatment with 2 mM l-lactate (NA and Lac + NA, respectively) determined by fitting exponentials; parameters in Supplementary Table 2. Error bars in graphs and bar charts denote the mean ± SEM; asterisks in bar charts indicate significant differences (one way ANOVA, *p < 0.05).