Abstract
The ventral pallidum (VP) is a key node in the neural circuits controlling relapse to drug seeking. How this role relates to different VP cell types and their projections is poorly understood. Using male rats, we show how different forms of relapse to alcohol-seeking are assembled from VP cell types and their projections to lateral hypothalamus (LH) and ventral tegmental area (VTA). Using RNAScope in situ hybridization to characterize activity of different VP cell types during relapse to alcohol-seeking provoked by renewal (context-induced reinstatement), we found that VP Gad1 and parvalbumin (PV), but not vGlut2, neurons show relapse-associated changes in c-Fos expression. Next, we used retrograde tracing, chemogenetic, and electrophysiological approaches to study the roles of VPGad1 and VPPV neurons in relapse. We show that VPGad1 neurons contribute to contextual control over relapse (renewal), but not to relapse during reacquisition, via projections to LH, where they converge with ventral striatal inputs onto LHGad1 neurons. This convergence of striatopallidal inputs at the level of individual LHGad1 neurons may be critical to balancing propensity for relapse versus abstinence. In contrast, VPPV neurons contribute to relapse during both renewal and reacquisition via projections to VTA. These findings identify a double dissociation in the roles for different VP cell types and their projections in relapse. VPGad1 neurons control relapse during renewal via projections to LH. VPPV neurons control relapse during both renewal and reacquisition via projections to VTA. Targeting these different pathways may provide tailored interventions for different forms of relapse.
Footnotes
The authors declare no competing financial interests.
Data reported in the paper are archived in the UNSW Long Term Data Archive (ID: D0235271). This work was supported by the National Health and Medical Research Council (GNT1098436, GNT1138062), the Australian Research Council (DE170100509), UNSW Major Research Equipment and Infrastructure Initiative, and UNSW School of Psychology. We declare no competing interests.
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