Neuro-immunological hypothesis of psychiatric diseases via microglia

Abstract

Microglia, major sources of free radicals and inflammatory cytokines, play crucial roles in brain homeostasis and various brain pathologies such as neurodegenerative diseases and neuropathic pain. Recent postmortem and imaging studies have indicated microglial activation in the brain of schizophrenic patients and patients who committed suicide. We have recently demonstrated that some kinds of antipsychotics and antidepressants such as selective serotonin reuptake inhibitors(SSRIs)significantly inhibit the release of nitric oxide and proinflammatory cytokines from activated microglia in vitro. Based on these results, we put forward a novel neuro-immunological hypothesis of psychiatric diseases via microglia. Microglia may play an important role in various psychiatric diseases by modulating inflammatory/immunological environments through moving around dynamically and releasing chemical mediators in the CNS. Our hypothesis shed new light on a novel therapeutic strategy for psychiatric diseases. Furthermore, microglia might be a key player in human mental activities, especially 'unconscious drives', from the standpoint of psychodynamic psychiatry. Microglia research has the potential to bridge the huge gap between biological psychiatry and psychoanalysis.