Fig. 4

Reduction of GIRK1 immunoparticles in post- and presynaptic compartments of APP/PS1 mice. Electron micrographs showing immunoparticles for GIRK1 in the stratum radiatum of the hippocampal CA1 field at 12 months of age, as detected using the SDS-FRL technique in wild type and APP/PS1 mice. A–C In wild type, immunoparticles for GIRK1 were detected forming clusters (pink circles) or scattered (pink arrows) in dendritic spines (s) and oblique dendrites (oDen) of CA1 pyramidal cells, as well as presynaptically along the extrasynaptic site and in the active zone (az, pink overlay) of axon terminals (at). D–F In APP/PS1, very low frequency of clusters or scattered (purple arrows) GIRK1 immunoparticles were observed in dendritic spines (s), oblique dendrites (oDen), or axon terminals (at). The E-face is free of any immunolabelling. G Quantitative analysis showing that the density of GIRK1 immunoparticles was significantly reduced in the APP/PS1 mice compared to age-matched wild type controls in the post- and presynaptic subcellular compartments analysed (Mann–Whitney test, ***p < 0.001; ****p<0.0001). Error bars indicate SEM. Scale bars: A–F, 0.2 μm