Single-cell sequencing of rodent ventral pallidum reveals diverse neuronal subtypes with non-canonical interregional continuity

The ventral pallidum (VP) was defined as a basal ganglia nucleus with dense input from ventral striatum. To further investigate a VP regional identity, we conducted a cross-species transcriptional characterization of VP cell types. We performed single nucleus RNA-sequencing of VP tissue from mice and rats and identified 16 VP neuronal subclasses with striking cross-species conservation. VP GABAergic neurons were surprisingly heterogeneous, consisting of 14 sub-classes from 3 developmental classes. Combining our sequencing data with a spatial atlas revealed that all VP subclasses extended beyond the traditional borders of VP. Integrating our VP data with prior sequencing data from striatal, hypothalamic, and extended amygdalar tissue confirmed that cell types are shared among these regions. Due to the role of VP in feeding behavior, we also assessed the transcriptional impact of high-fat diet consumption, which induced altered expression of genes involved in oxidative phosphorylation and inhibitory signaling. Overall, our results demonstrate that VP is not a transcriptionally discrete nucleus; rather, VP contains cell types with diverse expression patterns that overlap with regions beyond the basal ganglia.