TNF and depressive symptom measurement: Elevated expression of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), and nuclear factor kappa B (NF-κB) signaling have been identified in patients with depression and replicated in animal models of high-fat diet (HFD) and stress-induced behavioral despair [9].