Microglia provide structural resolution to injured dendrites after severe seizures

Although an imbalance between neuronal excitation and inhibition underlies seizures, clinical approaches that target these mechanisms are insufficient in containing seizures in patients with epilepsy, raising the need for alternative approaches. Brain-resident microglia contribute to the development and stability of neuronal structure and functional networks that are perturbed during seizures. However, the extent of microglial contributions in response to seizures in vivo remain to be elucidated. Using two-photon in vivo imaging to visualize microglial dynamics, we show that severe seizures induce formation of microglial process pouches that target but rarely engulf beaded neuronal dendrites. Microglial process pouches are stable for hours, although they often shrink in size. We further find that microglial process pouches are associated with a better structural resolution of beaded dendrites. These findings provide evidence for the structural resolution of injured dendrites by microglia as a form of neuroprotection. [Display omitted] •Cortical microglia form process pouches following severe experimental seizures•Microglial process pouches target beaded dendrites following severe seizures•Microglial process pouches are long lived with little evidence for phagocytosis•Microglial process pouches correlate with the structural resolution of dendrites Eyo et al. report that microglia form unique spherical structures in an experimental seizure model. Using live imaging, the authors characterize these structure that they call “microglial process pouches” and show that they colocalize with injured neuronal dendrites and are strongly correlated with the structural resolution of these injured dendrites.