Western blot was performed, according to a previously described method (Kim et al., 2015 (link)). Protein extracts from hippocampal tissues were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Protein separation was performed using 10% polyacrylamide with 0.05% bis-acrylamide. Proteins were then transferred to nitrocellulose and the blots were probed with anti-PI3K mouse monoclonal antibody (1:1,000, Santa Cruz Biotechnology, Santa Cruz, CA, USA), anti-Akt rabbit polyclonal antibody (1:1,000, Cell Signaling Technology Inc., Beverly, MA, USA), anti-GSK-3β rabbit polyclonal antibody (1:1,000, Santa Cruz Biotechnology), anti-synapsin I mouse monoclonal antibody (1:1,000, Santa Cruz Biotechnology), and anti-postsynaptic density-95 (PSD-95) mouse monoclonal antibody (1:1,000, Santa Cruz Biotechnology). Peroxidase anti-rabbit IgG (1:5,000, Vector Laboratories), and peroxidase anti-mouse IgG (1:10,000, Vector Laboratories) were used as the secondary antibodies. Immunoreactivity was detected by enhanced chemiluminescence (ECL) detection kit (Santa Cruz Biotechnology).