OXTR in the central nervous system is involved in the regulation of social cognition, anxiety, depression, and other psychological behaviors or emotions, with the activation of intracellular signaling pathways, such as the mitogen-activated protein kinase (MAPK), protein kinase C (PKC), and phospholipase C (PLC) signaling (Fitts et al., 2003; Zingg and Laporte, 2003; Yoshida et al., 2009; Carter, 2014; Kendrick et al., 2018). Here, OXTR is linked to major depressive disorder.