2.9 Immunohistochemistry staining
Paraffin-embedded brains were sectioned at a thickness of 5 μm. Sections were then dewaxed and followed by antigen retrieval using L.A.B solution (Polyscience, Inc) for 20 min. After the blockage of goat serum for 30 min, the sections were incubated with rabbit anti-p-tau (Ser396) (Sigma, SAB4504557, 1: 100) overnight at 4 °C. Sections were subsequently incubated with biotinylated secondary antibodies for 1 h and third antibody for 30 min at room temperature, and further developed in DAB for 3 min. Finally, the sections were dehydrated and sealed. The images were captured by a light microscope (Leica, DM4000B).