Nicotine-induced transcriptional changes and mitochondrial dysfunction in the ventral tegmental area revealed by single-nucleus transcriptomics.

Nicotine is widely recognized as the primary contributor to tobacco dependence. Previous studies have indicated that molecular and behavioral responses to nicotine are primarily mediated by ventral tegmental area (VTA) neurons, and accumulating evidence suggests that glia play prominent roles in nicotine addiction. However, VTA neurons and glia have yet to be characterized at the transcriptional level during the progression of nicotine self-administration. Here, a male mouse model of nicotine self-administration is established and the timing of three critical phases (pre-addiction, addicting, and post-addiction phase) is characterized. Single-nucleus RNA sequencing in the VTA at each phase is performed to comprehensively classify specific cell subtypes. Adaptive changes occurred during the addicting and post-addiction phases, with the addicting phase displaying highly dynamic neuroplasticity that profoundly impacts the transcription in each cell subtype. Furthermore, significant transcriptional changes in energy metabolism-related genes are observed, accompanied by notable structural alterations in neuronal mitochondria during the progression of nicotine self-administration. The results provide insights into mechanisms underlying the progression of nicotine addiction, serving as an important resource for identifying potential molecular targets for nicotine cessation.