Nicotine and tobacco smoke reshape neuronal signaling networks from a single-nucleus transcriptomic perspective.

Nicotine and cigarette smoke exposure significantly impact brain function, yet their distinct cellular and molecular mechanisms remain unclear. To address this, we conducted comprehensive single-nucleus RNA sequencing (snRNA-seq) analysis on whole-brain samples and specifically on the ventral tegmental area (VTA) of adult C57BL/6 mice following nicotine or smoke exposure. Our study identified 18 major transcriptionally distinct cell populations across the whole brain and 27 distinct clusters within the VTA, covering major neuronal and glial cell types. Differential gene expression and KEGG pathway enrichment analyses revealed distinct transcriptional responses: nicotine exposure was associated with enrichment of synaptic and addiction-related transcriptional pathways in neuronal populations, including dopaminergic and glutamatergic pathways, whereas smoke exposure was associated with broader enrichment of metabolic-, immune-, and endocrine-related pathways. CellChat predicted condition-associated communication differences, including higher inferred NRXN communication from excitatory neurons to oligodendrocytes and other excitatory neurons under nicotine exposure. Smoke exposure also increased oligodendrocyte PISD expression, a transcriptomic change potentially associated with mitochondrial phospholipid metabolism. Collectively, these data define cell-type-specific transcriptional and predicted communication signatures of nicotine and smoke exposure that require functional validation.