Sustained increase in [alpha]5GABA^sub A^ receptor function impairs memory after anesthesia

Many patients who undergo general anesthesia and surgery experience cognitive dysfunction, particularly memory deficits that can persist for days to months. The mechanisms underlying this postoperative cognitive dysfunction in the adult brain remain poorly understood. Depression of brain function during anesthesia is attributed primarily to increased activity of y-aminobutyric acid type A receptors (GABA^sub A^R), and it is assumed that once the anesthetic drug is eliminated, the activity of GABA^sub A^Rs rapidly returns to baseline and these receptors no longer impair memory. In this article, using a murine model, the researchers found that a single in vivo treatment with the injectable anesthetic etomidate increased a tonic inhibitory current generated by α5 subunit-containing GABA^sub A^Rs (α5GABA^sub A^Rs) and cell-surface expression of α5GABA^sub A^Rs for at least 1 week. The sustained increase in α5GABA^sub A^R activity impaired memory performance and synaptic plasticity in the hippocampus. Inhibition of α5GABA^sub A^Rs completely reversed the memory deficits after anesthesia.