Fig. 5.

Biphasic astrocytic glutamate release occurring in both a Ca²⁺-dependent and -independent manner. a Imaging astrocytic glutamate release with green fluorescent sensor iGluSnFR expressed on the outer face of cell membrane. b CTR: repetitive fluorescence signals upon glutamate exposure. c Dose–response curve for astrocyte-expressed iGluSnR (n = 6–11 cells per concentration). d Dual-color imaging of astrocytic Ca²⁺ by the red sensor GECO-R and glutamate release by iGluSnFR. Right, ATP application evoked Ca²⁺ rise and glutamate release, which were both suppressed by BAPTA chelation of intracellular Ca²⁺. e Aβ25–35 triggered a biphasic glutamate release, which started prior to Ca²⁺ rise and was further increased during Ca²⁺ elevation. f, g Chelating astrocytic Ca²⁺ with BAPTA partially reduced Aβ-induced glutamate release, confirming its occurrence in both Ca²⁺-independent and -dependent manner (n = 10–11 cells per condition). Scale bars, 5 µm