Nicotine e-cigarette vapor inhalation effects on nicotine & cotinine plasma levels and somatic withdrawal signs in adult male Wistar rats.

Introduction:
This manuscript reports a study examining the effects of nicotine e-cigarette vapor inhalation on blood-nicotine concentrations, blood-cotinine concentrations, and somatic withdrawal signs over time in rats. The study utilized Electronic Nicotine Delivery Systems (ENDS) to expose male Wistar rats to various concentrations of nicotine e-cigarette vapor for 11 days and measured the outcomes at different time points.

Key Points:

* The study found that exposure to nicotine e-cigarette vapor produced somatic withdrawal symptoms and measurable blood-nicotine and blood-cotinine levels in rats.
* The somatic withdrawal signs and blood-nicotine/cotinine levels changed according to the concentration of nicotine in vape solution, number of days of vapor exposure, time since termination of vapor exposure, and whether withdrawal was spontaneous or precipitated.
* The concentration-dependent time course analysis of somatic withdrawal signs and blood-nicotine/cotinine levels in rats after single or repeated bouts of nicotine e-cigarette vapor inhalation is the first of its kind.
* ENDS can be used to vaporize and deliver various drugs to rodents, and labs are working to establish reliable e-cigarette vapor self-administration using operant tasks that can be learned, extinguished, and altered according to drug concentrations in the vape solution.
* Non-contingent chronic nicotine exposure and nicotine self-administration procedures have evolved over the years, with ENDS being used to deliver nicotine vapor to rats.
* The study found time-dependent somatic withdrawal signs that were higher following exposure to higher concentrations of nicotine vapor and precipitation of withdrawal with systemic mecamylamine injection.
* Blood-nicotine and blood-cotinine levels emerged and varied over time in a concentration-dependent manner following 1 or 10 sessions of non-contingent nicotine vapor inhalation.

Main Message:
The study provides valuable information on the concentration-dependent time course analysis of somatic withdrawal signs and blood-nicotine/cotinine levels in rats after single or repeated bouts of nicotine e-cigarette vapor inhalation, using ENDS to deliver nicotine vapor to rats. The study highlights the potential of ENDS to vaporize and deliver various drugs to rodents and the need for further research in this area to establish reliable e-cigarette vapor self-administration using operant tasks that can be learned, extinguished, and altered according to drug concentrations in the vape solution. The study also emphasizes the importance of considering the concentration of nicotine in vape solution, number of days of vapor exposure, time since termination of vapor exposure, and whether withdrawal is spontaneous or precipitated, when examining the effects of nicotine e-cigarette vapor inhalation on blood-nicotine concentrations, blood-cotinine concentrations, and somatic withdrawal signs over time in rats.

Montanari C, Kelley LK, Kerr TM, Cole M, Gilpin NW. Nicotine e-cigarette vapor inhalation effects on nicotine & cotinine plasma levels and somatic withdrawal signs in adult male Wistar rats. Psychopharmacology. 2020;237(3):613-625. doi:10.1007/s00213-019-05400-2