In CUMS-induced spontaneous diabetic rats, DBD (4.0 g/kg) and its main active ingredient ferulic acid (1.36 mg/kg) could increase serum and hippocampal BDNF levels to improve depression-like behavior, an effect that might relate to the activation of the CREB/TrkB signaling pathway (Wang et al., 2020b) (Table 1; Figure 1). Here, BDNF is linked to major depressive disorder.