Melatonin synthesized by activated microglia orchestrates the progression of microglia from a pro-inflammatory to a recovery/repair phenotype
Microglia, the sentinels of the central nervous system, are responsible for the surveillance and the innate defense against pathogen or danger/damage-associated molecular patterns. The response is fine-tuned to restrain pro-inflammatory responses, preserving neighboring cells. At the injured area, microglia temporarily shift to a pro-inflammatory phenotype (M1), followed by anti-inflammatory (M2) phenotypes. The duration and magnitude of the pro-inflammatory phase are finely regulated to avoid unnecessary loss of brain tissue.