Neurological effects in the offspring after switching from tobacco cigarettes to e-cigarettes during pregnancy in a mouse model.

Maternal smoking is currently a public health concern and has been associated with a number of complications in the offspring. E-cigarettes are gaining popularity as a "safer" alternative to tobacco cigarettes during pregnancy, however, there are a limited number of studies to suggest that it is actually "safe." Balb/C female mice were exposed to ambient air (n = 8; Sham), or tobacco cigarette smoke (n = 8; SE) before gestation, during gestation and lactation. A third group was exposed to cigarette smoke before gestation followed by e-cigarette aerosols during gestation and lactation (n = 8; Switch). Male offspring (12-week old, n = 10-14/group) underwent behavioral assessments to investigate short-termmemory, anxiety, and activity using the novel object recognition and elevated plus maze tests. Brains were collected at postnatal day (P)1, P20, and Week 13 for global DNA methylation, epigenetic gene expression, and neuronal cell counts. The offspring from mothers switching to e-cigarettes exhibited no change in exploration/activity but showed a decrease in global DNA methylation, Aurora Kinase (Aurk) A and AurkB gene expression and a reduction in neuronal cell numbers in the cornu ammonis 1 region of the dorsal hippocampus compared with the SE group. Continuous tobacco cigarette smoke exposure during pregnancy resulted in marked neurological deficits in the offspring. Switching to e-cigarettes during pregnancy reduced these neurological deficits compared with cigarette smoke exposure. However, neurological changes were still observed, so we therefore conclude that e-cigarette use during pregnancy is not advised.