STAT3 and major depressive disorder: In addition, disruption of the IL-17A-IL-17RA interaction was found to broaden the inflammatory response, which had a significant effect on mitochondrial fission, modulating mitochondrial fission sensitivity by inhibiting phosphorylation of downstream Drp-1 through STAT-3 signaling (56), which may lead to mitochondrial dynamics dysfunction, thereby affecting the development and progression of depression (23).