Microglia Control Neuronal Network Excitability via BDNF Signalling
Figure 1
Microglia control neuronal network excitability via secretion of BDNF. The left panel illustrates a schematic neuronal network in the mature CNS under normal conditions: microglia (blue ramified cells) are in their resting state; small inhibitory interneurons release GABA or Gly to repress the flow of signals across the network; normal KCC2 activity extrudes (black arrows) to maintain the gradient, and, consequently, flows in through GABAAR/GlyR channels to inhibit activity. The right panel illustrates the same network after an external event has induced microglial activation (red cells) and the release of microglial BDNF: BDNF-TrkB signaling causes downregulation of KCC2; accumulates in neurons and the gradient collapses; GABAAR/GlyR-mediated inhibition is less effective in controlling neuronal firing, and previously silent neuronal pathways are unmasked (yellow arrows).
