Expression of BDNF and TrkB was determined by western blot analysis, as described previously [6 (link),20 (link)]. Hippocampal tissues were homogenized in lysis buffer. Protein (30 μg) was separated on sodium dodecyl sulfate-polyacrylamide gels, and then transferred onto a nitrocellulose membrane. Rabbit anti-BDNF (1:1,000; Santa Cruz Biotechnology), rabbit anti-TrkB (1:1,000; Santa Cruz Biotechnology), and mouse anti-β-actin (1:1,000; Santa Cruz Biotechnology) antibodies were used as primary antibodies. Horseradish peroxidase-conjugated antimouse antibody for β-actin and antirabbit antibody for BDNF and TrkB were used as secondary antibodies.