In mice submitted to a CUMS model of depression, 8 weeks of treadmill exercise significantly improves hippocampal function, reducing levels of IL-1β, NF-kB, toll-like receptor 4 (TLR-4), myeloid differentiation factor 88 (MyD88) and TNF-α and increasing levels of IL-10 and the expression of miR-223 in this structure [173]. This evidence concerns the gene TLR4 and major depressive disorder.