*2.12. Nissl Staining*

Nissl staining was performed according to the previously used methods [34], so as to visualize the histological changes in the brain. The slides were washed with 0.01 M BPS, twice for 15 min, and stained with 0.5% cresyl violet solution (containing a few drops of glacial acetic acid) for 12 to 15 min. Then, the sections were washed with D-water and dehydrated in ethanols (70%, 95%, and 100%), and xylene was dropped on the slides and covered by using the non-fluorescent mounting medium. The neurodegeneration was visualized by light microscope, and the densities of the cells were counted by using ImageJ software.
