Gestational exposure to ambient fine particulate matter disrupts maternal hepatic lipid metabolism

Pregnancy is a unique physiological stage for females as well as a vulnerable period for pollutant exposure. The effect of gestational ambient fine particulate matter (PM_2.5) exposure on maternal lipid metabolism during pregnancy is rarely observed, and the mechanism is unknown. In the current study, pregnant C57BL/6 mice were randomly assigned to either ambient PM_2.5 or filtered air exposure chambers since gestational day (GD) 0. Meanwhile, non-pregnant female mice were housed as controls in each exposure chamber. PM_2.5 exposure exerted no significant effect on body weight gain or the body composition during pregnancy. Pregnant mice exposed to PM_2.5 demonstrated improved glucose tolerance, whereas non-pregnant mice showed an increased fasting blood glucose level after PM_2.5 exposure with no alterations in glucose tolerance. PM_2.5 exposure exerted no significant effect on total lipid content in serum during pregnancy, while an increased serum total lipid level was found in non-pregnant mice exposed to PM_2.5. PM_2.5 exposure had no effect on total liver lipid levels, it increased several triacylglycerol (TAG) species and total cholesterol esters (CEs) in pregnant mice but lowered a considerable amount in non-pregnant mice' livers. Furthermore, gestational exposure to PM_2.5 enhanced the expression of key enzymes in fatty acid uptake, de novo lipid synthesis, and β oxidation, and inhibited molecules for lipid export in mice liver. Conversely, PM_2.5 exposure upregulated proteins involved in hepatic lipolysis and lipid export in non-pregnant mice. These results suggest that the interference of PM_2.5 exposure during pregnancy on the lipid metabolism, particularly the hepatic lipid metabolism, differs from that during non-pregnancy. This study provides toxicological evidence that PM_2.5 exposure during pregnancy disrupts the lipid metabolism of the liver and provides a basis for protecting vulnerable populations.