2.5. Nissl staining
The mice from each group were deeply anesthetized by intraperitoneal
injection of 10% chloral hydrate and then subjected to transcardial
perfusion with 0.9% NaCl, followed by fixation with 4%
paraformaldehyde in 0.1 M phosphate buffer. Brain slices (5 μm) were
deparaffinized and immersed in cresyl violet (C0117, Beyotime
Biotechnology) for 10 min at room temperature. Brain sections were then
dehydrated in graded alcohol, mounted with neutral balsam and observed
under a light microscope. The hippocampal subregions including CA1, CA3
and DG were selected and viable neurons were calculated, respectively,
from different groups.