Targeting Mu opioid receptor neurons of the habenula to limit naloxone aversion

Opioid use disorder is a chronic, relapsing condition that continues to rise worldwide. Naloxone (Narcan®), an opioid antagonist, reverses overdose but triggers strong negative affect. The neuronal circuits underlying these aversive effects remain unclear. We previously identified mu opioid receptor–expressing habenular neurons (Hb-MOR) as key encoders of negative emotional states and hypothesized that they also mediate naloxone aversion.