Metformin attenuates the induction of experimental autoimmune encephalomyelitis by restricting the infiltration of mononuclear cells into the CNS, down-regulating the expression of pro-inflammatory cytokines [gamma interferone (IFN-γ), tumor necrosis factor alpha (TNF-α), IL-6, IL-17, and inducible NO synthase (iNOS)], cell adhesion molecules, matrix metalloproteinase 9, and chemokine [125]. The gene discussed is NOS2; the disease is experimental autoimmune encephalomyelitis.