Fig. 4

C3aR blockade reduces microglial phagocytic activity and synapse loss at 1 day after orthopedic surgery. Mice were randomly assigned to three groups (n = 5/group): sham + vehicle, surgery + vehicle, and surgery + C3aR antagonist (C3aRa). a Representative confocal images of double immunostaining of CD68 (green) and IBA1 (red); scale bar = 30 μm. b Quantification of CD68 occupancy in IBA1⁺ microglia. Representative images from western blotting of presynaptic marker SYP (c) and postsynaptic marker PSD-95 (e). Quantification of SYP (d) and PSD-95 (f). Linear regression analyses of the relationship between microglia CD68 reactivity and synaptic marker SYP (g) or PSD-95 (h). Data analyses were performed using one-way analysis of variance followed by Tukey post hoc test (b, d, f) or regression analysis (g, h). **p < 0.01, ***p < 0.001, ****p < 0.0001