BDNF and major depressive disorder: Moreover, current pathomechanisms of depression include disturbances of the hypothalamic-pituitary-adrenal axis (e.g., glucocorticoid receptor sensitivity [47]), neurotrophic homeostasis (e.g., brain-derived neurotrophic factor (BDNF) levels [48]), and inflammatory processes (e.g., migration inhibitory factor (MIF) [49]).