Fig. 4

Aβ-related neuropathology in OSK-KI mice. Abnormal tau phosphorylation, synapse loss, glial activation, and neuron loss were examined. (a) Brain sections were stained with PHF-1 antibody specific to pSer396/Ser404-tau. Photographs were taken from the hippocampal CA2/3 region. Scale bar = 30 μm. (b) Brain homogenates at 8 months were subjected to pSer396-tau sandwich ELISA. Each bar represents the mean ± SEM (n = 4 for each group). (c) Brain sections were stained with anti-synaptophysin antibody. Photographs were taken from the hippocampal CA3 region. Scale bar = 30 μm. Fluorescence intensities in a constant area were quantified as described previously [28]. Each bar represents the mean ± SEM (n = 3 for each group). AU, arbitrary unit. *p = 0.0019 versus non-KI and = 0.0093 versus hetero-KI, †p = 0.0052 versus non-KI and = 0.0424 versus hetero-KI, ‡p < 0.0001 versus non-KI and = 0.0278 versus homo-KI, ‡‡p = 0.0008 versus non-KI. (d) Hippocampal homogenates at 4 and 8 months were subjected to Western blot with antibodies to synaptophysin and actin. The signal densities were quantified. Each bar represents the mean ± SEM (n = 3 for each group). (e) Brain sections were stained with antibodies to Iba-1 (microglia) and GFAP (astrocytes). Photographs were taken from the hippocampus. Scale bar = 30 μm. (f) Brain sections at 24 months were stained with anti-NeuN antibody. Photographs were taken from the hippocampal CA2/3 region (HC) and entorhinal cortex (EC). Scale bar = 30 μm. Neu-N-positive neurons in an area within 300 μm along the pyramidal cell layer of the hippocampal CA3 region and in an area within 1000 μm along the layer II (the region between the two broken lines) of the entorhinal cortex were counted, essentially as described previously [26]. *p = 0.0448 versus non-KI and = 0.0245 versus hetero-KI, †p = 0.0285 versus non-KI and = 0.0207 versus hetero-KI (n = 4 for each group)