Age-dependent effects of vaping on the prefrontal cortex, ventral tegmental area, and nucleus accumbens

Electronic nicotine delivery systems (ENDS) are unique from combustible cigarettes due to the availability of flavor options which make these devices popular among adolescents. However, there are no preclinical investigations into the impact of vaporized nicotine on late-developing brain regions such as the prefrontal cortex. Here, we investigated how neuronal function and drug self-administration differed between adult-exposed and adolescent-exposed mice. Male and female adolescent and adult C57BL/6J mice were used in a 20-session e-Vape® self-administration (EVSA) assay. Brains were then extracted and acute slices were used for either patch-clamp electrophysiology or fast-scan cyclic voltammetry. Adolescent-exposed males exhibited greater reinforcement-related behavior compared to their adult-exposed counterparts. However, adolescent-exposed and adult-exposed females exhibited similar levels of reinforcement-related behavior. Adolescent-exposed mice exhibited significant increases in intrinsic excitability of medial prefrontal cortex (mPFC) pyramidal neurons. Additionally, reinforcement-related behavior observed during EVSA assays correlated with adolescent-exposed mPFC neuronal excitability. This did not occur in adult-exposed mice. In the ventral tegmental area (VTA), we observed that upregulation of nicotinic acetylcholine receptors (nAChRs) only correlated with nicotine self-administration in adult and not adolescent-exposed mice. The relationship between self-administration and changes in neuronal excitability in adolescent mice indicates that the mPFC may be important for adolescent nicotine dependence.