CNP and major depressive disorder: Decreased levels of MAG, MAL, CNPase, and MOBP, were also confirmed in animal models of depression (Liu et al., 2012, 2018; Makinodan et al., 2012; Luo et al., 2019; Takahashi et al., 2021) and in the human postmortem study in depressed patients (Aston et al., 2005; Rajkowska et al., 2015).