BDNF/TrkB Inhibitor (K252a) and Anti-bDNF Antibody Notably Antagonized the Increase in BDNF and Transient Receptor Potential Channels 6 Expression in the Hippocampal CA1 Neurons in the Perimenopausal Depression-Like Rats Treated by E2. The gene discussed is NTRK2; the disease is major depressive disorder.