BDNF and major depressive disorder: For example, Yu et al., Lu et al. and Sun et al., (Yu et al., 2017; Lu et al., 2018; Sun et al., 2020) all reported that vortioxetine administration significantly increased the hippocampal brain-derived neurotrophic factor (BDNF) -cAMP-response element binding protein (CREB) signaling cascade in rodent models of depression.