Several studies have further found that the hippocampal concentrations of the pro-inflammatory cytokines IL-6, IL-1β, and TNF-α are elevated in mice with depression-like behavior (Goshen et al., 2008; Mohamed et al., 2013; Hsieh et al., 2014; Tao et al., 2016). The gene discussed is IL1B; the disease is major depressive disorder.