Ca2+activity is required for injury-induced migration of microglia in zebrafishin vivo

Objectives Microglia are the resident immune cells in the brain. Brain injury can activate the microglia and induce its directional migration towards injury sites for exerting immune functions. While extracellular ATP released from the injury site mediates the directionality of activated microglia’s migration, what endows activated microglia with migration capability remains largely unexplored. Methods In the present study, we used the larval zebrafish as an in vivo model to visualize the dynamics of both morphology and Ca 2+ activity of microglia during its migration evoked by local brain injury. Results We found that, in response to local injury, activated microglia exhibited an immediate Ca 2+ transient and later elevated Ca 2+ bursts frequency during its migration towards the local injury site ( P < 0.01). Furthermore, suppression of Ca 2+ activities significantly retarded microglial migration ( P < 0.05). Conclusion Thus, our study suggests that intracellular Ca 2+ activity is required for activated microglia’s migration.