Knockdown of circHIPK2 expression in astrocytes ameliorated the depressive-like behavior induced by CUS. a Illustration of AAV microinjection and the experimental procedure. Mice were microinjected with the eGFP-labeled circCon or circHIPK2 shRNA AAV for 2 weeks, followed by CUS treatment for 4 weeks. b circHIPK2 levels decreased in circHIPK2 shRNA AAV-injected mice compared with those in circCon shRNA AAV-injected mice in both the control and CUS-treated groups. c Specific circHIPK2 expression knockdown in astrocytes attenuated the CUS-induced decrease in sucrose preference. d, e Specific circHIPK2 expression knockdown in astrocytes inhibited the CUS-induced increase in immobility time in the FST (d) and TST (e). N = 7–15 mice/group. f Specific circHIPK2 expression knockdown in astrocytes attenuated the CUS-induced decrease in GFAP expression. N = 6 mice/group. g Specific knockdown of circHIPK2 expression in astrocytes attenuated the astrocyte dysfunction induced by CUS. Representative images of astrocyte immunostaining for GFAP in mouse hippocampi, followed by 3D reconstruction and Sholl analysis. Scale bars, 50 μm. h Quantification of GFAP-positive cells per square millimeter2in mouse hippocampi. N = 4 mice/group. i–k Average branch number (i), total branch length (j), and total branch volume (k). n = 4 mice/group, 40 cells/group. *p < 0.05, **p < 0.01 and ***p < 0.001 vs. the circCon control group. #p < 0.05, ##p < 0.01 and ###p < 0.001 vs. the CUS-treated circCon group using one-way ANOVA followed by the Holm-Sidak test.