Animals were sacrificed with an overdose of pentobarbital and perfused transcardially with heparinized PBS. After opening the skull, the brains were carefully dissected on ice. One hemisphere was kept frozen at −80 °C for later biochemical analysis. The other hemisphere was fixed in 4% paraformaldehyde for 4 h and transferred to 25% sucrose for histological processing. 25 μm-thick sagittal cryosections were collected on Superfrost plus slides (Thermo Fisher Scientific) and stored at −80 °C until further use. For the thioflavin S staining, frozen brain sections were incubated in a solution of 0.01% thioflavin S (Sigma Aldrich) in distilled water for 8 min at RT, washed twice in 50% ethanol for 5 min, and twice in PBS for 10 min. For Gallyas staining, frozen brain sections were treated following a modified Gallyas-silver method. Slides were mounted in 80% glycerol and images of brain sections were taken on a Leica DM5500 microscope (Leica).