Fig. 6: After febrile seizures (FSs), microglia phagocytose inhibitory synapses through a complement cascade.

a CR3 mRNA levels in hippocampal extracts 1 hour and 4 hours after FSs. β-actin was used as an internal standard. Mean ± SD, n = 6 mice, Tukey’s test after one-way ANOVA. b Immunohistochemical images of microglia (Iba1) and CR3 in the middle molecular layer 6 hours after FSs. c Immunostained CR3 intensity in the middle molecular layer. Mean ± SD, n = 5 mice, Tukey’s test after one-way ANOVA. d Representative 3D reconstructed images of microglia (CX3CR1-GFP), lysosomes (CD68) and inhibitory presynapses (VGAT) 6 hours after FSs. e, f Excitatory (VGLUT1) and inhibitory (VGAT) presynaptic volume phagocytosed by microglia 6 hours after FSs. Mean ± SD, n = 5 mice, two-sided unpaired t test. g, i Immunohistochemical images of excitatory synapses (pre: VGLUT1; post: Homer1) and inhibitory synapses (pre: VGAT; post: Gephyrin) in the middle molecular layer at 24 hours after FSs. h, j Images of colocalized synaptic puncta corresponding to (g) and (i). k–n Colocalized synaptic puncta density (as shown in images of (h) and (j)) 24 hours and 72 hours after FSs shown as % of control. Mean ± SD, n = 5 mice, two-sided unpaired t test. o Inhibitory presynaptic (VGAT) volume phagocytosed by microglia in CR3 knockout (KO) mice 6 hours after FSs. Mean ± SD, n = 3 mice, two-sided unpaired t test. p Inhibitory synapse density in CR3 KO mice 24 hours after FSs. Mean ± SD, n = 3 mice, two-sided unpaired t test. q Seizure scores following kainic acid injection 72 hours after FSs. Mean ± SD, n = 15, 15, 8, 7 mice, two-way repeated-measures ANOVA (Time x Group Factor). Source data are provided as a Source Data file.