Pregnancy and Postpartum Effects of Electronic Cigarettes on Maternal Health and Vascular Function in the Fourth Trimester

Abstract

Pregnancy is a vulnerable time with significant cardiovascular changes that can lead to adverse outcomes, which can extend into the postpartum window. Exposure to emissions from electronic cigarettes (Ecig), commonly known as "vaping," has an adverse impact on cardiovascular function during pregnancy and post-natal life of offspring, but the postpartum effects on maternal health are poorly understood. We used a Sprague Dawley rat model, where pregnant dams are exposed to Ecigs between gestational day (GD)2-GD21 to examine postpartum consequences. Litter and dam health were monitored during the weaning period, and maternal vascular and endocrine function were assessed after weaning. Exposure to Ecig emissions during pregnancy led to fetal losses (i.e., reabsorption in utero) and reduced survival of pups during weaning compared to controls (air-exposed dams). We find that maternal vaping during pregnancy, with or without nicotine (or flavoring) results in maternal vascular and hormonal dysfunction (i.e., reduced prolactin, increased expression of sirtuin 1 deacetylase in the brain). Both 5 and 30W Ecig aerosol exposures resulted in significant impairment of middle cerebral artery reactivity to acetylcholine-mediated dilation (decreasing ~ 22 and ~ 50%, respectively). We also observed an increase in the number of extracellular vesicles (EVs) in plasma from 30-W group that persists up to 3-week postpartum and that these EVs impaired endothelial cell function when applied to in vitro and ex vivo assays. Our data suggest (1) Ecig vaping, even without nicotine or flavorings, during pregnancy alters maternal circulating factors that influence maternal and fetal health, (2) circulating EVs may contribute to the etiology of vascular dysfunction, and (3) that the window for recovery from vascular dysfunction in the dam is likely to be longer than the exposure window.

Keywords: Brain; Middle cerebral artery; Myography; Pregnancy; Vaping.

Fig. 1

Particle size distributions of aerosol generated during “puffs” created with the Ecig device set to 5W and 30W. The aerosol was sampled from the exposure chamber with an electrical low-pressure impactor show complex multi-modal particle size distributions with 3 major modes for 5W (at 0.046 µm, 0.151 and 0.427 µm) and 2 for 30W (at 0.175 and 0.460 µm). Count median particle diameter for the aerosol distribution at 5W and 30W were 0.336 and 0.395 μm, respectively. This shift of the distribution to the right with increasing wattage most likely occurred due to increased particle production and agglomeration at the higher wattage. Data from 3 technical replicates

Fig. 2

A Dam’s weight pre-pregnancy (i.e., before timed-mating) and on gestational day (GD)2, GD7, GD14, and GD20. n = 6–11 dams/group. rmANOVA *p < 0.05 for Ecig0–30W vs Air, ^Ecig50–5W, and ♦Ecig50–30W are p < 0.05 vs Air. B Total weight gain is the difference between the pre-pregnancy weight and GD20. Control = Air exposed dams. n = 9–11 dams/group. ANOVA *p < 0.05, **p < 0.01. Mean ± SE

Fig. 3

A Offspring loss due to reabsorption during pregnancy determined by the difference in offspring litter size and number of implantation sites. B Data from each litter showing initial litter size at birth and any pup death post partition (assessed at weaning, i.e., post-natal day 21). Connecting line shows number of pups at birth and at weaning for each respective litter, allowing quick determination of whether pup losses occurred during weaning (i.e., flat line = no losses). n = 8–11 dams/group (however, there are numerous cases of overlapping data from litters with similar numerical outcome that will appear to be single data point, but actually represents identical data from several dams (e.g., in the Air group 4 dams had 12 pups at birth, 3 dams had 13 pups, and 2 dams had 16 pups, thus Air group has data from n = 11 dam/litters). ANOVA *p < 0.05 compared to Air group

Fig. 4

A Maternal middle cerebral artery (MCA) vasodilatory response to dose–response of acetylcholine (ACh) and B maximal vessel response (from 10⁻⁴ M ACh). n = 5–11 offspring/group. ANOVA with post hoc Tukey analysis where ***p < 0.001 and ****p < 0.0001. Mean ± SE

Fig. 5

Data showing maximal dilation response to acetylcholine (ACh 10^–4 M) using pressure myography on ex vivo middle cerebral arteries (MCA) treated with A superoxide dismutase mimetic (Tempol) or B nitric oxide synthase inhibitor (L-NAME). n = 4–7 offspring/group ANOVA with post hoc Tukey analysis where **p < 0.01, ***p < 0.001, ****p < 0.0001. Mean ± SE

Fig. 6

Data showing extracellular vesicles (EVs) number and size distribution in plasma obtained from dams with exposure to A Ecig aerosol without nicotine (0 mg/mL, Ecig0), and B with nicotine (50 mg/mL, Ecig50), at 5W and 30W device power setting. Dams are exposed from gestational day 2 until 21 (i.e., birth). Controls are dams with exposure to ambient air during the same time. Blood samples (i.e., plasma) were collected from dams after weaning (postpartum day 21). n = 6–11 dams/group. ANOVA *p < 0.05 compared Air, ♦p < 0.05 compared to respective 5W condition

Fig. 7

Extracellular vesicles (EV) from plasma of dams collected on post-natal day (PD)21 treated on the middle cerebral arteries of female virgin rats. No EV, Air EV, and Ecig EV refer to the absence or presence of EV in combination to the response to acetylcholine (ACh). A Dose–response and B maximal response of the MCA to ACh (n = 4–8 animals). Percent cell proliferation in C HUVEC and D D3 cells were treated with EV’s before performing MTT assay (n = 5–9 EV-treated plates). ANOVA *p < 0.05, **p < 0.01, ****p < 0.0001. Mean ± SE