TLR4 and depressive disorder: Arctigenin (Xu et al., 2020), safflower extract (Chen et al., 2021), baicalin (Guo et al., 2019), Xiao-Chai-Hu-Tang (Shao et al., 2021), puerarin (Gao et al., 2021), etc. alleviated depression through TLR4 signaling pathways.