Escin, a natural triterpenoid saponin from Aesculus chinensis (Suoluozi), alleviates CUMS-induced depression-like behaviors by modulating both the BDNF/TrkB/CREB and Toll-like receptor 4 (TLR4)/Myeloid differentiation factor 88 (MyD88)/NF-κB signaling pathways (148). This evidence concerns the gene TLR4 and major depressive disorder.