CRH and major depressive disorder: 1991). Chronic stress usually leads to the activation of the HPA axis that are characterized by the increases in plasma CORT and CRH gene expression in the hypothalamus, leading to anxiety/depression‐related behavior in both rats and humans (Mastorakos et al. 2006). Meynen has reported that AVP gene expression in the SON and PVN were significantly increased in major depression (Meynen et al. 2006). Similarly, previous research also found that mRNA levels of CRH and AVPR in the PVN were increased in the depressed patients (Wang et al. 2008).