Agarose gel electrophoresis was carried out for the analysis of
DNA fragmentation. DNA from cerebral cortex was isolated according
to the manufacturer’s instructions provided with the kit
(DNA-zol reagent kit) and dissolved in Tris–EDTA buffer. DNA
samples were electrophoresed on 1.4% agarose gel using Tris–
boric acid-EDTA buffer at 40 V for 5 h. The gels were stained with
ethidium bromide and visualized under ultraviolet light.