The hippocampus was harvested 2 h after the behavioral analysis for the determination of HDAC2 (1:500; Abcam, UK), acetyl-H3K9 (1:2,000; Millipore, USA), acetyl-H4K12 (1:2,000;Millipore, USA), BDNF (1:500; Abcam, UK), TrkB (1:500; Abcam, UK), p-TrkB (1:1,000; Abcam, UK), p-CaMKII (1:500; Abcam, UK), p-CREB (1:200; Abcam, UK), caspase-3 (1:100; Abcam, UK), and anti-β-actin (1:1,000, Santa Cruz, USA) as previously described [19 (link)]. Bands were visualized by enhanced chemiluminescence and quantitated with the Image Quant Software (Syngene, Cambridge, UK).