Nicotine-free vapor inhalation produces behavioral disruptions and anxiety-like behaviors in mice: Effects of puff duration, session length, sex, and flavor.

Introduction:
This paper reports a study examining the effects of nicotine-free vapor inhalation on general and mood-disorder related behaviors in mice. The study also aims to determine how vapor puff durations, administration session length, flavored e-liquid, and sex alter behavior to provide a foundation of administration parameters.

Key Points:

* The study used 334 C57BL/6 mice, with 162 males and 172 females.
* Vapor inhalation was administered using an E-Vape™ delivery system, with a digital interface, vapor generator, Plexiglass chamber, and an air pump.
* The study measured the effects of vapor inhalation on locomotor activity, tail suspension test, and light-dark test.
* Mice were exposed to nicotine-free unflavored vapor puff durations (1, 3, 6, or 10 sec) and vapor administration session lengths (10 and 30 mins).
* The study also examined the effects of mecamylamine and the time-course of vapor-induced depression of LMa.
* additionally, mice were exposed to flavored (strawberry and adventurers tobacco blend) vapor inhalation and measured on locomotor activity, tail suspension test, and light-dark test.
* No significant effects of sex or flavor were found.

Main Message:
The study found that nicotine-free vapor inhalation produced anxiety-like behaviors, which is a concern as many adolescents vape nicotine-free flavored e-liquid. The study also demonstrated that vapor puff duration is an important variable to consider during research design as it can become a confounding variable and alter baseline behaviors. It is important to establish standard administration parameters for vapor inhalation studies to allow for replication between laboratories and to increase generalizability and translational value in the field.

Garrett PI, honeycutt SC, Marston C, et al. Nicotine-free vapor inhalation produces behavioral disruptions and anxiety-like behaviors in mice: Effects of puff duration, session length, sex, and flavor. Pharmacology, biochemistry, and behavior. 2021;206:173207. doi:10.1016/j.pbb.2021.173207