The effect of electronic cigarettes exposure on learning and memory functions: behavioral and molecular analysis

Abstract

Objective: Electronic cigarettes (ECIGs) are battery-powered devices that emit vaporized solutions for the user to inhale. ECIGs are marketed as a less harmful alternative to combustible cigarettes. The current study examined the effects of ECIG aerosol exposure on learning and memory, expression of brain derived neurotrophic factor (BDNF), and the activity of antioxidant enzymes in the hippocampus.

Methods: Male Wistar rats were exposed to ECIG aerosol, by a whole-body exposure system, 1 h/day for 1 week, 4 weeks, and 12 weeks. Spatial learning and memory were tested using the Radial Arm Water Maze (RAWM). Hippocampal BDNF protein level, and oxidative stress biomarkers (GPx, SOD, GSH, GSSG, GSH/GSSG ratio) were also assessed.

Results: ECIG aerosol exposure for 4 and 12 weeks impaired both short- and long- term memory and induced reductions in the hippocampus BDNF, SOD and GPx activities, and GSH/GSSG ratio (p < 0.05). No changes in any examined biomarkers were observed after 1-week exposure to ECIG aerosol (p > 0.05).

Conclusions: ECIG aerosol exposure impaired functional memory and elicited changes in brain chemistry that are consistent with reduced function and oxidative stress.

Keywords:

• Electronic cigarettes
• exposure
• memory
• oxidative stress
• biomarkers

Disclosure statement

Drs. Eissenberg and Shihadeh are paid consultants in litigation against the tobacco industry and also the electronic cigarette industry and are named on a patent for a device that measures the puffing behavior of electronic cigarette users. Dr. Eissenberg is also named on another patent for a smartphone app that determines electronic cigarette device and liquid characteristics.

Additional information

Funding

This study was supported by a grant [no. 387/2019] from the Deanship of Research at Jordan University of Science and Technology, Irbid, Jordan. Drs. Eissenberg and Shihadeh are supported by grant [number U54DA036105] from the National Institute on Drug Abuse of the National Institutes of Health and the Center for Tobacco Products of the U.S. Food and Drug Administration. The content is solely the responsibility of the authors and does not necessarily represent the views of the NIH or the FDA.