Fig. 2: Optogenetic astrocyte activation induces intracellular Ca²⁺ signal.

a Schematic illustration showing hGFAP-ChR2 generation by breeding hGFAP-CreERT2 and floxed-stop-ChR2-EYFP transgenic mice. b Left, representative confocal image showing ChR2 (green: EYFP⁺) colocalization in astrocytes (pink: GFAP⁺, purple: S100ß⁺). Yellow arrow, GFAP⁺/S100ß⁺/EYFP⁻ cells (n = 412 cells); white arrow, GFAP⁺/S100ß⁺/EYFP⁺ cells (n = 1206 cells). Scale bar, 50 μm. Right, percentage of ChR2-expressing astrocytes between wild-type control (n = 5) and hGFAP-ChR2 (n = 9). Two-tailed Mann−Whitney U-test (p = 0.002). Experiment was repeated three-times independently. c Ca²⁺ level in ChR2-expressing primary astrocytes with or without light stimulation (blue: mean trace, gray: individual activities). d Schematic illustration of experiment for astrocytic Ca²⁺ imaging in acute hippocampal slice. Right image, ROI for jRGECO1a-positive astrocytes. e Expression of ChR2 (green), jRGECO1a (red), and GFAP (pink) in hippocampus. Scale bar, 50 μm. f Heatmap representation and averaged trace of hippocampal astrocyte Ca²⁺ activities while delivering continuous light stimulation for 5 min (n = 46 cells, red: average, gray: standard error). Representative data from three independent experiments. **p < 0.01. See Supplementary Data for detailed statistics. Source data are provided as a Source Data file.