Microglia Activation and Gene Expression Alteration of Neurotrophins in the Hippocampus Following Early Life Exposure to E-cigarette Aerosols in a Murine Model.
Toxicol Sci. 2017 Nov 17. Epub 2017 Nov 17. PMID: 29161446
Judith T Zelikoff
Recent epidemiological data indicate that the popularity of electronic cigarettes (e-cigarettes), and consequently nicotine use, is rising in both adolescent and adult populations. As nicotine is a known developmental neurotoxin, these products present a potential threat for those exposed during early life stages. Despite this, few studies have evaluated the toxicity of e-cigarettes on the developing central nervous system (CNS). The goal of this study was to assess neurotoxicity resulting from early life exposure to electronic cigarette aerosols in an in vivo model. Specifically, studies here focused on neuro-parameters related to neuroinflammation and neurotrophins. To accomplish this, pregnant and neonatal C57BL/6 mice were exposed to aerosols produced from classic tobacco flavor e-cigarette cartridges (with [13 mg/ml] and without nicotine) during gestation (∼3-wk) and lactation (∼3-wk) via whole-body inhalation. Exposure to e-cigarette aerosols with and without nicotine caused significant reductions in hippocampal gene expression of Ngfr and Bdnf, as well as in serum levels of cytokines IL-1β, IL-2and IL-6. Exposure to e-cigarette aerosols without nicotine enhanced expression of Iba-1, a specific marker of microglia, in the CA1 region of the hippocampus. Overall, our novel results indicate that exposure to e-cigarette aerosols, with and without nicotine, poses a considerable risk to the developing CNS. Consequently, e-cigarettes should be considered a potential public health threat, especially early in life, requiring further research and policy considerations.