Resting microglial motility is independent of synaptic plasticity in mammalian brain.

Microglia are well known for their roles in brain injuries and infections. However, there is no function attributes to resting microglia thus far. Here we performed a combination of simultaneous electrophysiology and time-lapse confocal imaging in green fluorescent protein-labeled microglia in acute hippocampal slices. In contrast to CA1 neurons, microglia showed no spontaneous or evoked synaptic currents. Neither glutamate- nor GABA-induced current/chemotaxis of microglia was detected. Strong tetanic stimulation of Schaffer-collateral pathways that induce CA1 long-term potentiation did not affect microglial motilities. Our results suggest that microglia are highly reserved for neuronal protective function but not synaptic plasticity in the brain.