研究成果 Research Results
It has long been believed that microglia morphologically transform into the activated state by retracting their long processes and consuming pathogens when bacteria infect into the brain parenchyma. In the present study, however, we showed for the first time that murine cortical microglia extend their processes towards focally injected Porphyromonas gingivalis. This P. gingivalis-induced microglial process extension was significantly decreased during the dark (waking) phase than the light (sleeping) phase. The P. gingivalis-induced microglial process extension was mediated by P2Y6 receptors. Infection of P. gingivalis may induce the secretion of UDP from microglia at the site of infection, which in turn induces the process extension of the neighboring microglia.
Therefore, the circadian oscillation of P2Y6 receptors may limit the microglal process extension during dark (waking) phase, which may provide a circadian gating of the microglial response to infected bacteria.
The research achievement will be published online in Scientific Reports on July 21, 2016.
Schematic illustration of diurnal microglial process extension to the infected bacteria through the UDP-P2Y6R system. Infected bacteria induce microglial process extension by secretion of UDP from microglia around the infected area.