General anesthetics activate a potent central pain-suppression circuit in the amygdala

General anesthesia (GA) can produce analgesia (loss of pain) independent of inducing loss of consciousness, but the underlying mechanisms remain unclear. We hypothesized that GA suppresses pain in part by activating supraspinal analgesic circuits. We discovered a distinct population of GABAergic neurons activated by GA in the mouse central amygdala (CeA(GA) neurons). In vivo calcium imaging revealed that different GA drugs activate a shared ensemble of CeA(GA) neurons. CeA(GA) neurons also possess basal activity that mostly reflects animals' internal state rather than external stimuli. Optogenetic activation of CeA(GA) potently suppressed both pain-elicited reflexive and self-recuperating behaviors across sensory modalities and abolished neuropathic pain-induced mechanical (hyper-)sensitivity. Conversely, inhibition of CeA(GA) activity exacerbated pain, produced strong aversion and canceled the analgesic effect of low-dose ketamine. CeA(GA) neurons have widespread inhibitory projections to many affective pain-processing centers. Our study points to CeA(GA) as a potential powerful therapeutic target for alleviating chronic pain. Hua and Chen et al. show that general anesthesia activates a distinct population of central amygdala neurons and that these neurons can potently suppress pain responses through their widespread projections to many pain-processing centers in the brain.