A Possible Link between Microglial Process Dysfunction and Neuropsychiatric Disorders - Abstract
Pío del Río Hortega first discovered microglia by histological staining with silver carbonate. He thought that microglia with highly branched fine processes in the healthy brain were quiescent and called these cells as resting microglia. After brain injury, microglia changes their morphology into activated type, which has phagocytic activity at the sites of neuronal damage and inflammation. At 90 years after the discovery of microglia, resting microglia in the healthy brain were found to be very dynamic, much more than any other cells in a live mouse brain using the two-photon scanning laser microscope. Beyond the roles as brain-resident macrophages, many lines of evidence have revealed that microglia have essential roles in the maturation and maintenance of neuronal circuits in the brain through both elimination and formation of dendritic
spines through their processes. Furthermore, length and structural complexity of highly branched fine processes are regulated by microglial intrinsic molecular clock. Dysfunction of dendritic spine and disturbance of circadian clock system are widely accepted characteristic abnormalities in neuropsychiatric disorders. Therefore, the growing understanding of movement and functions of microglial processes may aid in the development of novel pharmacological interventions against neuropsychiatric disorders, which are associated with synapse loss and aberrant neuronal connectivity.