Fetal growth outcomes following peri-implantation exposure of Long-Evans rats to noise and ozone differ by sex

Colette N Miller,Andres R Henriquez,Mette C Schladweiler,Erica J Stewart,Janice A Dye,Mehdi S Hazari,Wendy M Oshiro,Samantha J Snow,Urmila P Kodavanti,Aimen K Farraj,Judy H Richards

doi:10.1186/s13293-019-0270-6

Abstract

BackgroundExposure to air pollution and high levels of noise have both been independently associated with the development of adverse pregnancy outcomes including low birth weight. However, exposure to such environmental stressors rarely occurs in isolation and is often co-localized, especially in large urban areas.MethodsThe purpose of this study was to compare the effects of combined exposure to noise (N) or ozone (O3), compared to either exposure alone. Long-Evans dams were exposed to air or 0.4 ppm ozone for 4 h on gestation day (GD) 5 and 6, coinciding with implantation receptivity. A subset of dams from each exposure group was further exposed to intermittent white noise (~ 85 dB) throughout the dark cycle following each inhalation exposure (n = 14 − 16/group). Uterine artery ultrasound was performed on GD 15 and 21. Fetal growth characteristics and indicators of placental nutrient status were measured at GD 21.ResultsExposure to ozone + quiet (O3 + Q) conditions reduced uterine arterial resistance at GD 15 compared to air + quiet (A + Q) exposure, with no further reduction by GD 21. By contrast, exposure to air + noise (A + N) significantly increased uterine arterial resistance at both GD 15 and 21. Notably, while peri-implantation exposure to O3 + Q conditions reduced male fetal weight at GD 21, this effect was not observed in the air + noise (A + N) or the ozone + noise (O3 + N) exposure groups. Fetal weight in female offspring was not reduced by ozone exposure alone (O3 + Q), nor was it affected by air + noise (A + N) or by combined ozone + noise (O3 + N) exposure.ConclusionsThese data indicate that exposure to ozone and noise differentially impact uterine blood flow, particularly at mid-gestation, with only ozone exposure being associated with sex-dependent fetal growth retardation in male offspring.

Highlights

Exposure to air pollution and high levels of noise have both been independently associated with the development of adverse pregnancy outcomes including low birth weight
These data indicate that exposure to ozone and noise differentially impact uterine blood flow, at mid-gestation, with only ozone exposure being associated with sex-dependent fetal growth retardation in male offspring
We have recently demonstrated that exposure to ozone during implantation receptivity resulted in reduced fetal weight at gestation day (GD) 21 in Long-Evans rats [3, 4]

Summary

Introduction

Exposure to air pollution and high levels of noise have both been independently associated with the development of adverse pregnancy outcomes including low birth weight. Exposure to such environmental stressors rarely occurs in isolation and is often co-localized, especially in large urban areas. Traffic-related noise pollution has been suggested to be an independent risk factor for the development of both acute and chronic cardiovascular conditions [8, 9] These relationships are hypothesized to be attributed to activation of the stress response, stimulation of the hypothalamic-pituitary-adrenal (HPA) axis as suggested by findings in animals exposed to 60–90 dB of varying types of noise including traffic recordings [10,11,12]

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