The neurobiology of major depressive disorder: Updates and perspectives from proteomics

Major depressive disorder (MDD) is a widespread and disabling condition whose etiology and pathophysiology are not fully understood. Furthermore, pharmacological treatment of MDD poses challenging aspects, including delayed therapeutic effects, ineffectiveness against the so-called "residual symptoms", and a high proportion of non-responder patients. On these bases, it is crucial to recognize the key molecular systems and mechanisms involved in the pathophysiology of MDD in order to improve diagnostic tools and develop more effective pharmacological strategies. In this context, proteomics is a highly effective tool for simultaneously identifying and quantifying a large number of proteins within biological samples. This review will describe and discuss proteomic data from stress-based experimental models of MDD as well as from human brains and bodily fluids (e.g., cerebrospinal fluid and plasma), with the aim of elucidating the neurobiological counterparts of this psychiatric disorder. These findings will be summarized in an attempt to provide comprehensive maps of the biological systems involved in MDD, offering new insights into the molecular basis of different disease subtypes and paving the way to personalized diagnostic and treatment strategies.