Fig. 11

Intranasal instillation of C3a promotes the microglia-mediated synaptic phagocytosis after captopril treatment. A Representative anti-C3ar (red) and anti-Iba1 (cyan) double immunostaining indicates that C3a nasal drip reverses the C3ar suppression in microglia following captopril treatment. Scale bar = 10 μm. B Quantification of C3ar (red) signal intensity within Iba1⁺ (cyan) microglia is shown. C, D Immunostaining of Cd68 (green), synapsin (red) and Iba1 (cyan) and quantification of microglia with Cd68⁺ signal in the hippocampal CA1 indicate that C3a significantly reverses the inhibitory effects of captopril on synaptic pruning by microglia. Scale bar = 10 μm. E Representative confocal images of synapsin (red) from pyramidale and radiatum layer in the hippocampal CA1 are shown. Scale bar = 5 μm. F Quantification of integrated signal intensity synapsin indicates C3a significantly reverses the therapeutic effects of captopril treatment on reducing synaptic loss in the pyramidale and radiatum layer in the hippocampal CA1. n = 9 images from 3 rats/group, ***p < 0.001, compared to KA; ^&p < 0.05, ^&&&p < 0.001, compared to KA + Cap, one-way ANOVA followed by Tukey’s post hoc test. Data are presented as mean ± SE