Fig. 1

Microglial activation increased in stressed mice and was alleviated by IL-10 treatment. Male wild-type mice were subjected or not (NS) to the learned helplessness paradigm and separated into 2 groups: non-learned helpless (NLH) and learned helpless (LH) mice, according to their number of failures out of 30 escapable shock trials (a) and were treated or not with vehicle (Veh.) or IL-10 (5 μg/mouse) 24 h and 1 h prior to sacrifice. Mice were perfused and brains were collected for immunostaining. b Diagram of the dorsal mouse hippocampus in cross-section highlighting three major anatomical regions of the perforant pathway: CA1, CA3, and the dentate gyrus (DG). Representative images of Iba1⁺ microglial cells in the dentate gyrus of vehicle-treated: non-shocked control (NS) (c), NLH (d), and LH (e) mice, and IL-10-treated: NS (h), NLH (i), and LH (j) mice. Enlarged images of representative microglial cells (white dashed outline) exhibiting the predominant morphology are included in each panel. f Number of Iba1⁺ microglial cells per 200,000 μm² sampling area within the dentate gyrus for each mouse. Each dot represents a mouse. Two-way ANOVA, F(2,21)_interaction = 10.60, F(1,21) _treatment = 17.44, F(2,21)_condition = 5.865, Bonferroni post hoc test, *p < 0.05, bars represent means ± SEM, n = 3-5 mice/group. g Microglial morphology (sphericity) was measured as the microglial cell body cross-sectional area within the dentate gyrus for each mouse. Each dot represents a mouse. Two-way ANOVA F(2,17)_interaction = 13.99, F(1,17)_treatment = 32.02, F(2,17)_condition = 8.281, Bonferroni post hoc test, *p < 0.05, bars represent means ± SEM, n = 3-5 mice/group. k Percentage of CD45^intIL-10⁺ microglial cells in the hippocampus of NS, NLH, and LH mice, measured by flow cytometry. Each dot represents a mouse. One-way ANOVA, F(2,21) = 8.895, Bonferroni post hoc test, *p < 0.05, bars represent mean ± SEM, n = 6–11 mice/group