Figure 2
A simplified integrative model for the pathophysiology of MDD and the potential targets for XYS. a–g Refer to seven major hypotheses for MDD. a 5-HT depletion, b neurotrophin deficiency, c circadian dysrhythmia, d neuroinflammation, e mitochondria dysfunction, f HPA hyperacbivity, g epigenetic variation, 5-HT 5-hydroxytryptamine, BDNF brain-derived neurotrophic factor, IFN-γ interferon γ, TNF-α tumor necrosis factor α, IL-6 interleukin 6, IDO indoleamine 2,3-dioxygenase, TDO tryptophan 2,3-dioxygenase, TRYCATs tryptophan catabolites, NMDA N-methyl-d-aspartic acid, GR glucocorticoid receptor, ACTH adrenocorticotropic hormone, CRH corticotropin releasing hormone.