Fig. 3

Increased microglial activation, and Aβ plaque deposition following eliminating microglia in AQP4^−/−/APP/PS1 mice. a Double immunofluorescence for total-Aβ and Iba1. Microglia were apparently activated in the cerebral cortex of AQP4^−/−/APP/PS1 mice, compared to those in APP/PS1 controls. Dot-like signals of total-Aβ (arrowheads) were frequently observed in AQP4^−/−/APP/PS1 microglial cells. b, c Quantification of Iba1-positive, and iba1 and total-Aβ double-positive area fraction in the cerebral cortex, respectively. d, f Double immunofluorescence and quantification for CD68 and Iba1. CD68-positive microglia (arrowheads) were apparently increased in the cerebral cortex of AQP4^−/−/APP/PS1 mice, compared to those in APP/PS1 controls. e, g Double immunofluorescence and quantification for Lamp1 and Iba1. Lamp1-positive microglia (arrowheads) were also apparently increased in the cerebral cortex of AQP4^−/−/APP/PS1 mice. h, i Triple immunofluorescence and quantification for Lamp1, total-Aβ, and Iba1. Aβ immunoreactive products were restrictively localized to Lamp1-positive lysosome of Iba1-positive microglia. j Iba1 positive microglia were almost eliminated in both APP/PS1 mice and AQP4^−/−/APP/PS1 with clodronate liposome treatment. k, l Brain sections stained by thioflavine-S and Aβ_1–40, respectively. Aβ plaque disposition was present at the cerebral cortex of AQP4^−/−/APP/PS1 mice received local injection of clodronate liposomes. m Double immunofluorescence for total-Aβ and NeuN. Total-Aβ immunoreactivity (arrowheads) was increased within the cytoplasm of NeuN positive neurons of AQP4^−/−/APP/PS1 mice injected clodronate liposomes. n–s Quantification of Iba1, thioflavine-S, Aβ_1–40, and total-Aβ-positive area fraction or number in the cerebral cortex, respectively. Data in c, f, g, and i were analyzed by Student’s t test and in b, n, q, and s were analyzed by the two-way ANOVA with Newman-Keuls post hoc test. Data are mean ± SEM, n = 4 per group, *p < 0.05; **p < 0.01; ***p < 0.001