Study: Microglia help awaken the brain from anesthesia, protect neurons from aftereffects

Editor's Note

A new study finds that the same cells that are involved in preventing damage to the central nervous system – called microglia – help to awaken the brain following anesthesia. The findings appeared January 4 in the journal Nature. 

Using electron-microscopy-based synaptic reconstruction, the researchers could see the microglia “dancing” around the brain, and how they wedged between neurons and synapses in what appeared to be an attempt to shield the neurons from sedation. The researchers likened microglia to police officers protecting the brain, suggesting that anesthesia side effects like delirium may be due to the microglia intervening too much. 

Researchers have known about these special immune cells in the brain for over 100 years, but microglia only became a serious research focus in the past 20 years. This is the first time they have identified the role of microglia in protecting neurons from the aftereffects of anesthesia, counteracting the sedative effects so that the brain can reawaken. 

More than a third of patients coming out of anesthesia experience strong side effects, including extreme drowsiness and delirium, or intense hyperactivity.