TLR4 and major depressive disorder: Escin significantly improved depression-like behaviors in rats with CUMS-induced depression and reduced the hippocampal IL-1β, TNF-α, and IL-6 levels by regulating the brain-derived neurotrophic factor/tropomyosin receptor kinase B/cAMP response element-binding protein and TLR4/MyD88/NF-κB signaling pathways [52].