120 MATERNAL EXPOSURE TO DIESEL ENGINE EXHAUST DURING PREGNANCY AFFECTS EARLY EMBRYO DEVELOPMENT IN A RABBIT MODEL

Abstract

Airborne pollution has been associated with various adverse effects on human reproductive health, especially intrauterine growth retardation and early pregnancy loss. However, few studies have analysed its effect on early development. Diesel exhaust particles (DEP) have been shown to alter blastocyst formation when diluted in embryo culture medium (2010 Toxicol Sci. 117, 200–208), but no data are available concerning the effect of maternal inhalation of diesel exhaust on early embryo development. Our study has been designed to answer this question using rabbit as a model and DEP doses mimicking daily exposure to traffic in large European cities. New Zealand female rabbits were superovulated by means of 5 subcutaneous administration of pFSH for 3 days before mating, followed 10 to 12 h later by an intravenous administration of 30 IU of hCG at the time of mating (natural mating). Dams were exposed to a representative air pollution mixture; that is, diluted diesel engine exhaust (1 mg m^–3; N = 14) or clean air (N = 12), for 1 h every morning and afternoon, from Day 3 to Day 6 post-coitum (dpc). At 6 dpc, in vivo-developed embryos were collected from uteri perfused with PBS and counted; their diameter was measured on pictures using ImageJ software (NIH, Bethesda, MD, USA). Another group of female rabbits was exposed to the same inhalation conditions from 3 to 27 dpc without superovulation treatment. Measures by ultrasound were performed on these dams at 7 dpc. Data were analysed by Mann-Whitney test and ANOVA, including dams as cofactor. At 6 dpc, number of embryos per dams was higher in exposed group compared with control (P < 0.05). In contrast, embryo diameter was significantly lower in the DEP exposed group compared with the clean air exposed group (P < 0.01). Gene expression analysis is being performed in these embryos. At 7 dpc, ultrasound measurements evidenced a decrease in embryo diameter, perimeter, and volume in the exposed group compared with control (P < 0.01, P < 0.01, and P < 0.01, respectively). These data indicate that repeated exposure to airborne pollution even for daily short periods affects early development. Consequences of maternal DEP exposure on feto-placental development are under investigation.