Figure 2. G_q activation in astrocytes elevates their Ca2+ levels.

(A) Scheme of G_q GPCR activation in astrocytes by ACh locally applied over stratum radiatum astrocytes. (B) Fluorescence images of an astrocyte showing selected domains in soma and processes (top), pseudocolor Ca²⁺ images before (basal) and after local application of ACh (bottom) (scale bar, 5 μm), and Ca²⁺ traces from domains shown in top right panel. (C) Left: Raster plot showing Ca²⁺ events for each ROI (somas (s) below reference line, processes (p) above reference line). Right: Average Ca²⁺ traces from responding somas (top) and processes (bottom). T-test compares 10s before and 10s after agonist. (D and E) Ca²⁺ event probability in somas (D) and processes (E) vs. time, and maximum values in different conditions. (F) Immunohistochemical images of AAV8-GFAP-hM3Dq-mCherry expression in the hippocampus. From left to right: Expression of mCherry, GFAP, NeuN, a merge of all three, and a higher magnification merge image showing colocalization of GFAP and mCherry (25x; scale bar, 20 μm; s.o., stratum oriens; s.p., stratum pyramidale; s.r., stratum radiatum). (G-K) as (A-E) but with local application of CNO to G_qDREADD expressing astrocytes instead of ACh. Data are represented as mean ± SEM. P < 0.05 (*), P < 0.01 (**), and P < 0.001 (***).