The dynorphin/kappa opioid receptor (KOR) system in the brain regulates both stressful experiences and negative, aversive states during withdrawal from drugs of abuse. We explored the role of this system during acute withdrawal from long-term alcohol drinking, focusing on the bed nucleus of the stria terminalis (BNST), a region strongly implicated in alcohol-withdrawal induced alterations of behavior. Male C57BL/6J mice were subjected to repeated forced swim tests, home cage exposure to a predator odor, and a visual threat after eight weeks intermittent access to alcohol or water. Systemic injection of KOR antagonist norBNI reversed alcohol-related differences in immobility time during the second swim test and reduced burying behavior in response to predator odor, but did not affect behavioral response to visual threat. In dynorphin-GFP reporter mice, c-Fos immunoreactivity was increased in dynorphin-containing neurons after repeated swim stress and alcohol drinking. Using dynorphin-GFP mice, there was enhanced spontaneous excitatory synaptic drive onto dynorphin neurons in the BNST after alcohol-drinking mice underwent forced swim stress. Finally, knockdown of dynorphin in the BNST using a viral shRNA affected swim stress behavior and responses to TMT in alcohol drinkers and controls, but did not affect alcohol drinking. These studies confirm BNST dynorphin recruitment during acute withdrawal as playing a key role in altered behavioral responses to stressful stimuli.
bioRxiv Subject Collection: Neuroscience