Effects of a High-Fat Diet and Docosahexaenoic Acid during Pregnancy on Fatty Acid Composition in the Fetal Livers of Mice

Abstract

A high-fat diet (HFD) during pregnancy promotes fat accumulation and reduces docosahexaenoic acid (DHA) levels in the liver of the offspring at postnatal ages, which can depend on fetal sex. However, the prenatal mechanisms behind these associations are still unclear. Thus, we analyzed if an HFD alters DHA content and the expression of molecules related to fatty acid (FA) metabolism in the fetal liver. Female C57BL/6 mice were fed a control diet or HFD for 4-6 weeks before pregnancy until the gestational day (GD) 17.5. A subgroup of each diet received DHA (100 mg/Kg) orally from GD 6.5 until 16.5. On GD 17.5, maternal livers, placentas, and livers from male and female fetuses were collected for FA profiling with gas-chromatography and gene expression of molecules related to FA metabolism using qPCR. PPAR-α protein expression was evaluated using Western blot. The gene expression of placental FA transporters was also assessed. An HFD increased eicosapentaenoic acid (EPA) and decreased DHA levels and protein expression of PPAR-α in the fetal livers of both sexes. DHA increased the gene expression of Ppara, Cpt1, and Acsl1 in the livers of female fetuses. Therefore, an HFD reduces DHA levels and PPAR-α, a master regulator of gene expression, in the fetal liver. In turn, the livers of female fetuses seem to be more sensitive to DHA action.

Keywords: docosahexaenoic acid; fetal liver; high-fat diet; maternal liver; placenta; pregnancy.

Figure 1

Study design. CD: control diet; HFD: high-fat diet.

Figure 2

Characterization of dams fed with a control diet (CD) or high-fat diet (HFD) and treated with vehicle (sunflower oil) or docosahexaenoic acid (DHA) during pregnancy. (A,B) Pregestational weight gain and food intake; (C) gestational weight gain; (D–F) subcutaneous, retroperitoneal, and mesenteric fat depots; (G) maternal liver weight. Values are means ± SEM. Two-way ANOVA followed by Sidak’s post-test was performed to calculate the differences. *** p < 0.001 and * p < 0.05 between CD and HFD. M = mating.

Figure 3

Maternal metabolic parameters at gestational day (DG) 17.5. (A,B) Glucose levels and area under the curve (AUC) during an oral glucose tolerance test (OGGT); (C) fasting insulin serum concentration; (D) homeostatic model assessment (HOMA-IR); (E–G) fasting triglycerides, cholesterol and HDL; (H) percentage of intrahepatic fat content. Values are means ± SEM. Two-way ANOVA followed by Sidak’s post-test was performed to calculate the differences.

Figure 4

Biometric measurements in fetuses from dams fed with a control diet (CD) or high-fat diet (HFD) and treated with vehicle (sunflower oil) or docosahexaenoic acid (DHA) during pregnancy. Fetal and placental weight, fetal–placental weight ratio, liver weight, and liver–body weight ratio in male (A–D) and female fetuses (E–H). Values are means ± SEM. Two-way ANOVA followed by Sidak’s post-test was performed to calculate the differences. ^b p < 0.05 between HFD-vehicle and HFD-DHA groups.

Figure 5

Composition of n-3 polyunsaturated fatty acids in the placentas and livers of male and female fetuses from dams fed with a control diet (CD), high-fat diet (HFD), and treated with vehicle (sunflower oil) or docosahexaenoic acid (DHA) during pregnancy. Levels of eicosapentaenoic acid (C20:5 n-3, EPA), docosapentaenoic acid (C22:5 n-3, DPA), and docosahexaenoic acid (C22:6 n-3, DHA) in placentas (A–F) and fetal livers (G–L). Values are means ± SEM. Two-way ANOVA followed by Sidak’s post-test was performed to calculate the differences.

Figure 6

Gene expression of placental fatty acid transporters and regulators of fatty acid metabolism in the fetal livers of male and female fetuses from dams fed with a control diet (CD), high-fat diet (HFD), and treated with vehicle (sunflower oil) or docosahexaenoic acid (DHA) during pregnancy. Gene expression of Mfsd2a, Lipg, Scl27a4, and Cd36 in placentas from male and female fetuses (A,C). Gene expression of Ppara, Cpt1, and Acsl1 in the livers of male and female fetuses (B,D). Values are means ± SEM. Two-way ANOVA followed by Sidak’s post-test was performed to calculate the differences.

Figure 7

Protein expression of peroxisome proliferator-activated receptor alpha (PPAR-α) in the fetal livers of male and female fetuses from dams fed with a control diet (CD), high-fat diet (HFD), and treated with vehicle (sunflower oil) or docosahexaenoic acid (DHA) during pregnancy. Protein expression of PPAR-α in the fetal liver (A,B). Correlation between protein expression of PPAR-α with the content of DHA in the fetal liver (C,D). Values are means ± SEM. Two-way ANOVA followed by Sidak’s post-test was performed to calculate the differences. Correlation coefficients were computed using the Pearson correlation test.