Behavioral and Pharmacokinetic Assessment of Nicotine e-Cigarette Inhalation in Female Rats

Abstract

Abstract Introduction Nicotine and tobacco use remain high both globally and in the United States, contributing to large health care expenditures. With a rise in e-cigarette use, it is important to have clinically relevant models of inhaled nicotine exposure. Aims and Methods This study aims to extend prior preclinical nicotine inhalation animal data to females and provide both behavior and serum pharmacokinetics. We tested two inhalation doses of nicotine (24 mg/mL and 59 mg/ mL) and compared these to injected doses (0.4 mg/kg and 1 mg/kg). In addition, we assessed locomotor behavior after the same doses. Blood was collected at 10- and 120-minutes post-administration. We assessed nicotine and cotinine serum concentrations by LC–MS/MS. Results Showed that while nicotine serum concentrations for the respective high and low-dose administrations were similar between both routes of administration, the route had differential effects on locomotor behavior. Inhaled nicotine showed a dose-dependent decrease in locomotor activity while injected doses showed the opposite trend. Conclusions Our results indicate that the route of administration is an important factor when establishing preclinical models of nicotine exposures. Given that the overall use of e-cigarettes in vulnerable populations is on the rise, our study provides important behavioral and pharmacokinetic information to advance our currently limited understanding of the effects of nicotine vapor exposure. Implications This study highlights behavioral differences between different routes of administration of similar doses of nicotine. Using a low and high dose of nicotine, we found that nicotine serum concentrations were similar between the different routes of administration. Our results indicate that different routes of administration have opposing effects on locomotor activity. These findings provide important implications for future behavioral models.