TNF and treatment resistant depression: In view of the role of dysfunction of the HPA axis, anorexigenic peptides, and pro-inflammatory cytokines in the pathophysiology of TRD and the potential association between MECT and these serum indices, we investigated whether the HPA axis (cortisol), anorexigenic peptides (nesfatin-1), and pro-inflammatory cytokines (CRP, TNF-α, IL-6, and IL-1β) play a role in the mechanism that contributes to the effects of MECT in elderly patients with TRD.