BDNF and depressive disorder: Since the synthetic sites of BDNF in the central region of hippocampus are mainly in the CA1, CA3, and the hilus of dentate gyrus (Zakharenko, 2003; Lu et al., 2008), it is proposed that induction of the proliferation of endogenous neural stem cells and upregulation of BDNF may be a new strategy for the treatment of depression.