Fig. 3: Microglial depletion by PLX5622 ameliorated POCD-associated neuroinflammation, cognitive impairment, synaptic plasticity, and dendritic spine pathology.

A Representative immunofluorescence images showing staining for ACLY (yellow), microglial marker IBA1 (red), and nuclei marker DAPI (blue) in 20-month-old POCD mice treated with or without PLX5622. Right panels: fluorescence intensity profiles for control and PLX5622-treated groups. Scale bar: 20 μm. n = 5 mice in each group, **p < 0.01, all values represent mean ± standard deviation. Independent two-tailed Student’s t tests. B Immunofluorescence staining depicting astrocytic marker GFAP (green), glutamate transporter EAAT1 (red), acetylated p65 (yellow), and nuclei marker DAPI (blue). Right panels: corresponding fluorescence intensity profiles comparing control and PLX5622-treated groups. Scale bar: 20 μm. n = 5 mice in each group, *p < 0.05, **p < 0.01, all values represent mean ± standard deviation. Independent two-tailed Student’s t tests. C Representative immunofluorescence images showing dendritic marker MAP2 (green), microglial marker IBA1 (red), and nuclei marker DAPI (blue). Intensity profiles are presented for both control and PLX5622-treated groups. Scale bar: 50 μm. n = 5 mice in each group, *p < 0.05, **p < 0.01, all values represent mean ± standard deviation. Independent two-tailed Student’s t tests. D Time course showing glutamate release (% baseline) in hippocampal slices from POCD mice treated with or without PLX5622. Arrows indicate stimulation. n = 5 mice in each group/time point, **p < 0.01, two-way ANOVA with Newman–Keuls multiple comparison test. E Representative swimming trajectories in Morris water maze tests for POCD mice treated with or without PLX5622. F Quantification of escape latency (left panel) and number of crossings over the platform location (right panel) in the Morris water maze test. n = 15 mice in each group, *p < 0.05, **p < 0.01; all values represent mean ± standard deviation. independent two-tailed Student’s t tests. G Representative field excitatory postsynaptic potentials (fEPSP) recorded from hippocampal slices (left inset indicates recording and stimulating electrode positions). Traces from control and PLX5622-treated POCD miceshown. “1” = baseline fEPSP trace before HFS (pre-LTP induction); “2” = fEPSP trace recorded at the late phase after HFS. H Quantification of normalized fEPSP slopes (left panel) and long-term potentiation (LTP) time course following high-frequency stimulation (HFS) (right panel). n = 10 mice in each group, **p < 0.01; all values represent mean ± standard deviation. Independent two-tailed Student’s t tests. Golgi staining illustrating hippocampal dendritic spine morphology (J) and representative high-magnification images of dendritic spines (K). Scale bars are indicated. Quantitative analysis of spine density (L) and mushroom spine density (M) per 10 μm dendritic segment. n = 30 dendritic segments analyzed from 5 mice per group, **p < 0.01; all values represent mean ± standard deviation. Independent two-tailed Student’s t tests.