Integrated single cell and spatial mapping of habenula circuitry to identify projection-specific molecular pathways associated with opioid exposure.

PROJECT SUMMARY The national opioid epidemic is a significant public health crisis requiring accelerated efforts to translate mechanistic studies into therapeutic developments. Substance use disorders (SUDs) feature dysregulation of brain reward circuits, especially dopaminergic systems governing motivated behavior. The habenula (Hb) is a key reward circuitry hub that sends direct projections to the ventral tegmental area (VTA), as well as other aminergic centers, to modulate reward seeking. Hb circuit dysfunction is associated with addiction, but the molecular mechanisms mediating this dysfunction, especially in the context of opioid use disorder (OUD) are unknown. Here we propose to use integrated single cell and spatial transcriptomic approaches to map molecular changes associated with chronic opioid self-administration in specific cell populations across the rodent Hb (Aim 1). Using retrograde labeling and nuclear tagging, we will also generate transcriptomic signatures for Hb neurons projecting to the VTA (Hb-VTA projections) and evaluate their susceptibility to molecular changes associated with chronic opioid exposure (Aim 2). Finally, we will integrate these complimentary rodent datasets with molecular data we are generating in the post-mortem human Hb in the context of OUD as part of an ongoing NIDA-funded award (1R01DA55823) to identify specific Hb cell populations and projection neurons enriched in genes associated with opioid addiction in the human brain (Aim 3). The proposed study will generate the first spatially-resolved atlas of opioid-induced gene expression changes in the rodent Hb at cellular and circuit resolution. Integration of this molecular map with clinical gene sets in the context of OUD will help translate insights from rodent models into cell type- and circuit-based therapeutic approaches for the treatment of addiction.