CNR2 and depressive disorder: This conclusion is strongly supported by the previous studies that showed that knockout of Cnr2 in the brain could attenuate psychomotor, depression- and anxiety-like behaviors in mice (Liu Q.R. et al., 2017) and that blocking Tlr4 could reduce the anxiety- and depression-like behaviors (Strekalova et al., 2015; Zhang et al., 2020).