Effects Of Pregnancy Exposures To Airborne Particulate Matter (PM) On Embryo Development In ICR Mice

ObjectiveLarge amounts of studies have shown that air pollution associates with human health,and has manifold adverse effects on pregnant women and fetus resulting in an increase of birth defect incidence and decline of the population quality. Now we pay more attention to whether or not Airborne Particulate Matter(PM) pollutant affects the development of embryo. In this experiment, we used ICR mouse acutely exposed pregnant mice to PM as the experimental object to establish the PM-exposure pregnant mouse model. At gestational duration the mice were administered by Phosphate Buffered Saline (PBS)(blank control)or PM suspension at different doses via the observation and comparison among the groups,to investigate the acute toxic effect of PM on embryonic development of ICR mice, dose-response relationship and the possible mechanisms, and to lay a good foundation for further study on the influence of airborne particulate matter on the human fetal development.MethodsIn this experiment, we used SPF-grade ICR adult mice (male 40 and female 40) as the experimental object, through a conventional mating to get access to pregnancy. Mice were divided randomly into five groups according to the similarity in their body weights,each group has 8 mice. In the duration of pregnancy(from the first day of finding vaginal plug, which indicated pregnancy, to the 20th), after fully anesthetized by ethylether, according to the reforming technique for exposing the mouse lung to particles aspirated from the pharynx, the experimental groups were administered for PM suspension at different doses at every third day(over-dose: 69.2μg /μl,high dose:1.85μg /μl,medium dose:0.52μg /μl,low dose:0.09μg /μl), the control group were administered for PBS at every third day.Detection Indexes:1) The weight gain of the pregnant mice at 1th,7th,14th,18th of pregnancy;2)The length of gestation days,the number of absorption, abnormality and stillbirth in neonatal mice;3) The weight,stem length and tail length of the neonatal mice;4) The rate of Intrauterine Growth Retardation (IUGR);5)The liver coefficient and lung coefficient;6) The histology changes of lung and liver in neonatal mice;7) The expressions of mRNA and protein in CYP1A1 (lung)and CYP1A2(liver).Results1,The weight gain of the pregnant mice: on the 1st day,there were no significant differences between the groups in weight gain (P> 0.05). On the 14th and the 18th day, the weight gain of the over-dose group was significantly reduced compared with the blank control and the other experimental groups (P <0.05);2,The length of gestation days:compared with the blank control and the other experimental groups,the length of gestation days was significantly shortened in the over-dose group, (P<0.05); no obvious difference among the four other groups was found (P> 0.05);3,The weight of neonatal mice: compared with the blank control, the weight of neonatal mice in over-dose group was significantly reduced (P<0.05); compared with the blank control, there were no significant differences in the weight of neonatal mice in the high,medium and low dose groups, though there was a downward trend when the dose increased (P> 0.05);4,The rate of IUGR: compared with the blank control and the other experimental groups, the rate in over-dose group was significantly higher(P<0.05); compared with the blank control, there were no significant differences in the rate in the high,medium and low dose groups, though there was a downward trend when the dose increased (P>0.05);5,The stem length and tail length:compared with the blank control and the other experimental groups, the stem length and tail length in over-dose group were significantly shorter(P<0.05);6,The rate of abnormality: compared with the blank control and the other experimental groups, the rate of abnormality in over-dose group was significantly higher(P<0.05); There were no significant differences in the rate of abnormality between the other groups;7,The organ coefficient: compared with the blank control and the other experimental groups, the liver coefficient and lung coefficient in over-dose group were significantly higher(P<0.05);8,The expressions of mRNA and protein in CYP1A1 and CYP1A2:compared with the blank control group,the expressions were significantly higher in over-dose group(P<0.05).ConclusionsThis animal experiment tentatively confirms that: the National Ambient Air Quality Standards about PM EPA made in 2002 is safe to mothers and their fetus.1,Success in the establishment of animal model. We found an eminent embryotoxicity of PM as indicated by a decreased weight gaining and shortened pregnancy duration in the pregnant mice exposed to PM (especially the over-dose group) and the adverse outcome included premature birth, low birth weight, IUGR, stillbirth, and resorpted fetus.2,With the concentration of over-dose of 20,000μg/m3, PM do have adverse effect on the development of fetus and can lead to adverse pregnant outcome.3,If the concentration of PM is high, certain components could possibly pass through the placenta and do harm to the lung and liver of the fetus.4,The expressions of mRNA and protein in CYP1A1 and CYP1A2 are up-regulated by the induction of PM.