Fig. 4
Prefrontal tDCS mitigates hippocampal microglia-mediated neuroinflammation in 7- and 12-month-old Tg2576 mice. a Confocal images (scale: 50 μm) of Iba1+ cells in the hippocampus of 7-month-old WT and Tg2576 mice receiving tDCS or Sham stimulation. Nuclei are counterstained with DAPI. b Stereological count of Iba1+ cells (WT Sham: n = 7; WT tDCS: n = 5; Tg Sham: n = 4; Tg tDCS: n = 4; 2-way RM-ANOVA: interaction, F1,16 = 6.166, p = 0.0245; treatment, F1,16 = 9.375, p = 0.0075; genotype, F1,16 = 4.763, p = 0.0443. WT Sham–Tg Sham *p = 0.0167; WT tDCS–Tg Sham *p = 0.0118; Tg Sham–Tg tDCS *p = 0.0116, with Tukey’s post hoc). c Somatic area of microglia (n = 4 mice/group, 2 males and 2 females; 2-way RM-ANOVA: interaction, F1,12 = 9.344, p = 0.0100; treatment, F1,12 = 2.947, p = 0.1117; genotype, F1,12 = 12.86, p = 0.0037; WT Sham–Tg Sham **p = 0.0025, WT tDCS–Tg Sham *p = 0.0128, Tg Sham–Tg tDCS *p = 0.0246, with Tukey’s post hoc). d 3D-reconstruction of microglia (scale: 10 μm) and Sholl analysis (changes are marked by * for WT Sham vs. Tg Sham and by ° for Tg Sham vs. Tg tDCS; n = 4 mice/group, 2 males and 2 females; 2-way RM-ANOVA: Intersection (genotype): interaction, F6,36 = 9.002, p < 0.0001; distance, F6,36 = 396.2, p < 0.0001; genotype, F1,6 = 12.18, p = 0.0130; WT Sham–Tg Sham ****p < 0.0001 at 10–20 μm, *p = 0.0152 at 30 μm; Intersection (treatment): interaction, F6,36 = 2.129, p = 0.0737; distance, F6,36 = 295.0, p < 0.0001; treatment, F1,6 = 2.752, p = 0.1482; Tg Sham–Tg tDCS: °p = 0.0140 at 20 μm; Process length (genotype): interaction, F6,36 = 14.33, p < 0.0001; distance, F6,36 = 599.5, p < 0.0001; genotype, F1,6 = 13.18, p = 0.0110; WT Sham–Tg Sham ****p < 0.0001 at 20–30 μm; Process length (treatment): interaction, F6,36 = 3.057, p = 0.0160; distance, F6,36 = 314.0, p < 0.0001; treatment, F1,6 = 3.523, p = 0.1096; Tg Sham–Tg tDCS °°p = 0.0085 at 20 μm, °p = 0.0349 at 30 μm, with Sidak’s). e–f Iba1 staining (scale: 50 μm) and plot showing microglia number in 12-month-old WT and Tg2576 mice (WT Sham/WT tDCS/Tg Sham: n = 5 mice/group; Tg tDCS: n = 4 mice; 2-way RM-ANOVA: interaction, F1,15 = 9.072, p = 0.0088; treatment, F1,15 = 13.51, p = 0.0023; genotype, F1,15 = 7.581, p = 0.0148; WT Sham–Tg tDCS **p = 0.0025, Tg Sham–Tg tDCS **p = 0.0018, WT tDCS–Tg tDCS **p = 0.0061). g Somatic area of microglia (n = 4 mice/group, 2 males and 2 females. 2-way RM-ANOVA: interaction, F1,12 = 4.654, p = 0.0520; treatment, F1,12 = 10.45, p = 0.0072; genotype, F1,12 = 11.10, p = 0.0060; WT Sham–Tg Sham *p = 0.0102, WT tDCS–Tg Sham **p = 0.0028, Tg Sham–Tg tDCS *p = 0.0115). h 3D microglia reconstruction and Sholl analysis (n = 4 mice/group, 2 males and 2 females; 2-way RM-ANOVA: Intersection (genotype): interaction, F6,36 = 2.414, p = 0.0460; distance, F6,36 = 281.1, p < 0.0001; genotype, F1,6 = 0.5911, p = 0.4712; WT Sham–Tg Sham **p = 0.0065 at 10 μm; Intersection (treatment): interaction, F6,36 = 5.130, p = 0.0007; distance, F6,36 = 436.1, p < 0.0001; treatment, F1,6 = 23.63, p = 0.0028; Tg Sham–Tg tDCS °°°°p < 0.0001 at 10 μm, °°p = 0.0051 at 20 μm. Process length (genotype): interaction, F6,36 = 3.616, p = 0.0066; distance, F6,36 = 397.1, p < 0.0001; genotype, F1,6 = 0.4088, p = 0.5462; WT Sham–Tg Sham *p = 0.0123 at 20 μm; Process length (treatment): interaction, F6,36 = 6.156, p = 0.0002; distance, F6,36 = 682.4, p < 0.0001; genotype, F1,6 = 12.90, p = 0.0115; Tg Sham–Tg tDCS °p = 0.0426 at 10 μm, °°°°p < 0.0001 at 20 μm, with Sidak’s)