Abstinence-dependent dissociable central amygdala microcircuits control drug craving

We recently reported that social choice-induced voluntary abstinence prevents incubation of methamphetamine craving in rats. This inhibitory effect was associated with activation of protein kinase-Cδ (PKCδ)-expressing neurons in central amygdala lateral division (CeL). In contrast, incubation of craving after forced abstinence was associated with activation of CeL-expressing somatostatin (SOM) neurons. Here we determined the causal role of CeL PKCδ and SOM in incubation using short-hairpin RNAs against PKCδ or SOM that we developed and validated. We injected two groups with shPKCδ or shCtrl_PKCδ into CeL and trained them to lever press for social interaction (6 d) and then for methamphetamine infusions (12 d). We injected two other groups with shSOM or shCtrl_SOM into CeL and trained them to lever press for methamphetamine infusions (12 d). We then assessed relapse to methamphetamine seeking after 1 and 15 abstinence days. Between tests, the rats underwent either social choice-induced abstinence (shPKCδ groups) or homecage forced abstinence (shSOM groups). After test day 15, we assessed PKCδ and SOM, Fos, and double-labeled expression in CeL and central amygdala medial division (CeM). shPKCδ CeL injections decreased Fos in CeL PKCδ-expressing neurons, increased Fos in CeM output neurons, and reversed the inhibitory effect of social choice-induced abstinence on incubated drug seeking on day 15. In contrast, shSOM CeL injections decreased Fos in CeL SOM-expressing neurons, decreased Fos in CeM output neurons, and decreased incubated drug seeking after 15 forced abstinence days. Our results identify dissociable central amygdala mechanisms of abstinence-dependent expression or inhibition of incubation of craving.