Developing an efficient E-cigarette aerosol generation and exposure system for rodent models with aerosol characteristics equivalent to those inhaled by E-cigarette users

Abstract
E cigarettes (E-cigs) are increasingly popular worldwide, in particular, among youths. E-cigs may contribute to
nicotine addiction and are unlikely to discourage conventional cigarette smoking. Mainstream and second-hand
E-cig aerosols contain, in addition to nicotine, detectable levels of toxins including carcinogens and heavy
metals such as formaldehyde, benzene, nitrosamines, cadmium and lead. Therefore health risk and toxicology
studies on animal models exposed to E-cig aerosol, not limited to nicotine, are urgently needed. We propose to
develop a system designed for E-cig exposure to rodent models. With the support of our NIDA/NIH Phase I
grant, we designed and built ten prototypes including hardware and software that control 3-4 E-cigs and timing
of activation that can simulate the vaping pattern of E-cig users. We have characterized the aerosol particle
size distribution and mass concentration in the breathing zone of the rodent exposure chamber. We have
tested the prototype with acute and chronic rodent experiments. We have optimized the parameters of aerosol
exposure and showed that the system can generate rodent models with nicotine circadian pharmacokinetics
resembling human E-cig users. This application is to further develop and commercialize the product line for the
E-cig research community. Aim 1. To build, upgrade and commercialize the product line of efficient E-cig
aerosol generation and exposure systems delivering E-cig aerosol to rodents through inhalation with
characteristics equivalent to those inhaled by human E-cig users. We will upgrade the system to integrate
our ValveLink 8.2 technology. With USB connections, a computer can independently control up to 64 channels
at 5-6 channels per animal exposure chamber. We will make E-cig holders for different E-cigs available in the
marketplace including the NIDA standardize research E-cigarette (SREC). We will incorporate a Collison
nebulizer to generate saline aerosol for control. We will make a product for rodent E-cig self-administration for
studying addiction that includes software controlling two nose-poke sensors that either activate E-cigs or
control aerosol when poked. Aim 2. To validate the E-cig aerosol generation and exposure system with
acute and chronic animal experiments that produce E-cig exposure animal models for a variety of
research needs including the study of addiction. We will test the system with behavioral experiments such
as conditioned place preference (CPP), withdrawal signs with chronic intermittent E-cig exposure and E-cig
self-administration experiments in rodents (rats or mice). In addition to validating the device, these experiments
are significant in understanding E-cig reinforcement and dependence. Our products will meet the needs of the
E-cig research community and advance the field to enable testing potential toxicities of E-cigs in animal models
as well as facilitate new therapeutic discovery e.g., for nicotine addiction. Our products will be a powerful tool
for studying the effects of E-cig vaping on the cardiovascular, respiratory and nervous systems, on metabolism,
carcinogenesis, pregnancy and teratogenicity as well as their underlying mechanisms.Project Narrative
As E-cigarettes (E-cigs) are a relatively new product, research is needed to determine their long-term
detrimental effects on human users while appropriate methods and devices for relevant E-cig exposure in
animal models are lacking. We propose to develop a system designed for E-cig exposure in rodent models.
This system can generate clinically relevant animal models with nicotine levels/pharmacokinetics comparable
to those of human E-cig users for research, and allow investigators to uncover potential detrimental and
beneficial effects on human health as well as to develop therapeutics related to E-cig use.