Memory and Learning in Offspring Exposed to Maternal Vaping

Abstract

IntroductionElectronic cigarettes (e‐cigs) have increased in popularity world‐wide and are marketed as a safe alternative to smoking, even in the context of pregnancy. This is alarming, given that gestation represents a critical developmental period, and the lack of studies examining off‐spring outcomes following in utero exposure to vaping. We hypothesize that in utero e‐cig exposure, with or without nicotine, would adversely affect the cognitive development of offspring in rats.MethodsPregnant female Sprague‐Dawley rats were exposed 5 days/week to either Air, e‐cig with no nicotine (e‐cig0), or e‐cig with liquid containing 18 mg/ml nicotine (e‐cig18) starting at gestation day 2 until postnatal day 21 (when pups were weaned) using a 2‐chamber whole‐body exposure system (Scireq InExpose). Daily exposure consisted of 30 puffs over 1‐hour each day from a tank‐style e‐cig device (Joyetech eGrip OLED) using a 5‐sec activation @17.5W. Average total particulate matter was ~120 mg/m3 each day. Male and female F1 pups (n=8–14) from each group began a series of behavioral testing starting at postnatal day 25, which included Open Field, Hot Plate Test, Step‐Through Passive Avoidance (PA) test, and Morris Water Maze (MWM) for spatial memory and learning evaluation.ResultsIn MWM, all pups had the same level of learning within each test day (short‐term inter‐trials, <30 mins) and by the last (5th) day of testing. However, there was a trend towards reduced learning retention overnight in e‐cig18 pups, but not in E‐cig0, (Trial × Treatment interaction p<0.01), as seen by increased swim distances on the first trial of each day. During the final MWM probe all groups covered more distance in the target quadrant (site of the submerged platform) compared to the opposing quadrant, but the e‐cig0 and e‐cig18 pups covered more distance in the target quadrant compared to the air pups (p<0.05). During the learning trial, e‐cig0 initially took more time (p<0.01) to step‐through in PA (aversive learning) test. However, memory retention to adverse stimuli was not different across all the groups. There were no significant differences in nociceptive behaviors (i.e. Hot Plate test), nor locomotor, anxiety or willingness explore behaviors (i.e. Open Field test) between the exposure groups.ConclusionWe found evidence that e‐cig with nicotine (e‐cig18) resulted in reduced over‐night learning retention but demonstrated enhanced short‐term memory function (<30 mins) in both e‐cig0 and e‐cig18. No neurological or locomotor deficits were observed that would confound cognitive behavioral testing. Future studies will determine if and how this behavior changes in later stages of development through repeated measure testing. Our present findings suggest electronic cigarettes, even nicotine‐free products, affect the learning process.Support or Funding InformationSTRIDE Fellowship supported by APS and a grant from the National Heart, Lung and Blood Institute (NHLBI; 1 R25 HL115473‐01) (JO), WVU Rodent Behavior Core staff (NIGMS: P20‐GM109098), WVU Cancer Institute Philip R Dino Innovative Research Grant (IMO)This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.