TNF and major depressive disorder: Furthermore, the critical inflammatory factors including IL-1β, TNF-α, caspase-1, IL-2, IL-6, and IL-18 were measured to examine the action of Rg1 on inflammatory responses in CUS rats, as subsequent studies have concluded that neuroinflammation is a crucial factor recognized to be entangled in the occurrence of depression (Kohler et al., 2016).