Abstract
BackgroundAirborne pollution is a rising concern in urban areas. Epidemiological studies in humans and animal experiments using rodent models indicate that gestational exposure to airborne pollution, in particular diesel engine exhaust (DE), reduces birth weight, but effects depend on exposure duration, gestational window and nanoparticle (NP) concentration. Our aim was to evaluate the effects of gestational exposure to diluted DE on feto-placental development in a rabbit model.Pregnant females were exposed to diluted (1 mg/m3), filtered DE (NP diameter ≈ 69 nm) or clean air (controls) for 2 h/day, 5 days/week by nose-only exposure (total exposure: 20 days in a 31-day gestation).ResultsDE exposure induced early signs of growth retardation at mid gestation with decreased head length (p = 0.04) and umbilical pulse (p = 0.018). Near term, fetal head length (p = 0.029) and plasma insulin and IGF1 concentrations (p = 0.05 and p = 0.019) were reduced. Placental function was also affected, with reduced placental efficiency (fetal/placental weight) (p = 0.049), decreased placental blood flow (p = 0.009) and fetal vessel volume (p = 0.002). Non-aggregated and “fingerprint” NP were observed at various locations, in maternal blood space, in trophoblastic cells and in the fetal blood, demonstrating transplacental transfer. Adult female offspring were bred with control males. Although fetoplacental biometry was not affected near term, second generation fetal metabolism was modified by grand-dam exposure with decreased plasma cholesterol (p = 0.008) and increased triglyceride concentrations (p = 0.015).ConclusionsRepeated daily gestational exposure to DE at levels close to urban pollution can affect feto-placental development in the first and second generation.Electronic supplementary materialThe online version of this article (doi:10.1186/s12989-016-0151-7) contains supplementary material, which is available to authorized users.
Highlights
Airborne pollution is a rising concern in urban areas
Head length was significantly decreased (−4 %, p = 0.029) and abdominal perimeter tended to be decreased (−4 %, p = 0.076) in exposed fetuses compared to controls
Placental efficiency, which is defined as the fetal to placental weight ratio, i.e., the number of grams of fetus per gram of placenta, was significantly decreased (−12.3 %, p = 0.049) in the exposed group compared to controls
Summary
Airborne pollution is a rising concern in urban areas. Epidemiological studies in humans and animal experiments using rodent models indicate that gestational exposure to airborne pollution, in particular diesel engine exhaust (DE), reduces birth weight, but effects depend on exposure duration, gestational window and nanoparticle (NP) concentration. Studies in human populations are limited in terms of the ability to explore toxicological mechanisms underlying the effects of DE on the developing fetus, and to explore the specific role of volatile fractions and associated PM. To investigate this aspect, inhalation studies in animal models (mostly rodents) have been performed using various exposure times, various gestational windows and with varying concentrations of ultrafine particles, i.e. particles in the nanometer size range (NP), which are abundant in DE [9]. Inhaled 11-15 nm cadmium oxide NP did not reach the fetus in a study in mice [15], suggesting that the inhalation route may not lead to the transfer of NP to the fetus
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