Nissl staining

Nissl staining was performed as described previously (Qin et al., 2022). Paraffin-embedded sections were dewaxed with 0.5% cresyl violet at room temperature (RT), hydrated, and stained with Nissl dye at RT for 10 min. The sections were dehydrated and sealed. Finally, each section was observed under an optical microscope (Nika A1*R. Japan), and the Nissl-positive cells were counted. For the Nissl staining, 5 images were used for statistical analysis of mice in the Con-AAV-KA group and AAV-RNAi-KA group. The number of Nissl bodies in stained tissue sections was observed in the hippocampus by light microscopy. Surviving neurons were assessed based on the presence or absence of Nissl bodies.