Background: Feeding oxidized fats causes activation of peroxisome proliferator-activated receptor alpha (PPARalpha) in the liver of rats. However, whether feeding oxidized fat during pregnancy also results in activation of PPARalpha in fetal liver is unknown. Thus, this study aimed to explore whether feeding oxidized fat during pregnancy causes a PPARalpha response in fetal liver. Two experiments with pregnant rats which were administered three different diets (control; oxidized fat; clofibrate as positive control) in a controlled feeding regimen during either late pregnancy (first experiment) or whole pregnancy (second experiment) were performed.
Results: In both experiments pregnant rats treated with oxidized fat or clofibrate had higher relative mRNA concentrations of the PPARalpha-responsive genes acyl-CoA oxidase (ACO), cytochrome P450 4A1 (CYP4A1), L-type carnitin-palmitoyl transferase I (L-CPT I), medium-chain acyl-CoA dehydrogenase (MCAD), and long-chain acyl-CoA dehydrogenase (LCAD) in the liver than control rats (P < 0.05). In addition, in both experiments fetuses of the oxidized fat group and the clofibrate group also had markedly higher relative mRNA concentrations of ACO, CYP4A1, CPT I, MCAD, and LCAD in the liver than those of the control group (P < 0.05), whereas the relative mRNA concentrations of PPARalpha, SREBP-1c, and FAS did not differ between treatment groups. In the second experiment treatment with oxidized fat also reduced triacylglycerol concentrations in the livers of pregnant rats and fetuses (P < 0.05).
Conclusion: The present study demonstrates for the first time that components of oxidized fat with PPARalpha activating potential are able to induce a PPARalpha response in the liver of fetuses. Moreover, the present study shows that feeding oxidized fat during whole pregnancy, but not during late pregnancy, lowers triacylglycerol concentrations in fetal livers.