Choline prevents fetal overgrowth and normalizes placental fatty acid and glucose metabolism in a mouse model of maternal obesity

Abstract

Maternal obesity increases placental transport of macronutrients, resulting in fetal overgrowth and obesity later in life. Choline participates in fatty acid metabolism, serves as a methyl donor and influences growth signaling, which may modify placental macronutrient homeostasis and affect fetal growth. Using a mouse model of maternal obesity, we assessed the effect of maternal choline supplementation on preventing fetal overgrowth and restoring placental macronutrient homeostasis. C57BL/6J mice were fed either a high-fat (HF, 60% kcal from fat) diet or a normal (NF, 10% kcal from fat) diet with a drinking supply of either 25 mM choline chloride or control purified water, respectively, beginning 4 weeks prior to mating until gestational day 12.5. Fetal and placental weight, metabolites and gene expression were measured. HF feeding significantly (P<.05) increased placental and fetal weight in the HF-control (HFCO) versus NF-control (NFCO) animals, whereas the HF choline-supplemented (HFCS) group effectively normalized placental and fetal weight to the levels of the NFCO group. Compared to HFCO, the HFCS group had lower (P<.05) glucose transporter 1 and fatty acid transport protein 1 expression as well as lower accumulation of glycogen in the placenta. The HFCS group also had lower (P<.05) placental 4E-binding protein 1 and ribosomal protein s6 phosphorylation, which are indicators of mechanistic target of rapamycin complex 1 activation favoring macronutrient anabolism. In summary, our results suggest that maternal choline supplementation prevented fetal overgrowth in obese mice at midgestation and improved biomarkers of placental macronutrient homeostasis.

Keywords: Choline; Fetal overgrowth; Gestational diabetes; Nutrient transport; Obesity; Placenta.

Fig. 1

Weight gain and intraperitoneal glucose tolerance (IGT) of dams fed different diets. (A) Weight gain was measured both before timed-mating and during gestation (E0.5–E12.5). (B) IGT tests were conducted at E11.5 with 2g/kg D-glucose injected. (C) The area under the curve of the IGT tests. NFCO: n = 8; NFCS: n = 6; HFCO: n = 8; HFCS: n = 7. Values are mean ± standard error of mean (SEM); different letters indicate P < 0.05. NF: normal-fat diet; HF: high-fat diet; CO: control; CS: choline supplemented.

Fig. 2

Fetal and placental weight at E12.5. Different diets were fed to dams from 4 weeks before timed-mating to gestational day 12.5. Solid bars, NFCO, n = 8; shaded bars, NFCS, n = 6; open bars, HFCO, n = 8; hatched bars, HFCS, n = 7. n is the number of dams. All placentas and fetuses in each dam were included in the analysis. Values are mean ± standard error of mean (SEM); different letters indicate P < 0.05. NF: normal-fat diet; HF: high-fat diet; CO: control; CS: choline supplemented.

Fig. 3

Thickness of placental layers at E12.5. (A) Histological appearance of representative placentas. (B) Thickness ratios of placental layers in the NFCO (n = 3), HFCO (n = 3), and HFCS (n = 3) groups. Different diets were fed to dams from 4 weeks before timed-mating to gestational day 12.5. n is the number of dams. Two placentas in each dam were included in the analysis. Values are mean ± standard error of mean (SEM); different letters indicate P < 0.05; ns: not significant. D, decidua; J, junctional zone; L, labyrinth; NF: normal-fat diet; HF: high-fat diet; CO: control; CS: choline supplemented.

Fig. 4

Placental glucose and fatty acid metabolism at E12.5. Different diets were fed to dams from 4 weeks before timed-mating to gestational day 12.5. (A) mRNA abundance was measured by real-time PCR. (B) Macronutrient transport proteins were assessed by western blot. (C) Glycogen and triglyceride accumulation in the placenta were measured using assay kits. Solid bars, NFCO, n = 8; shaded bars, NFCS, n = 6; open bars, HFCO, n = 7; hatched bars, HFCS, n = 6. n is the number of dams. Two placentas in each dam were included in the analysis. Values are mean ± standard error of mean (SEM); different letters indicate P < 0.05; ns: not significant. Acox1: Peroxisomal acyl-coenzyme A oxidase 1; Cd36: fatty acid translocase; Cpt1b: Carnitine palmitoyltransferase 1b; Fas: fatty acid synthase; Fatp: fatty acid transport protein; Glut: glucose transporter; Lpl: lipoprotein lipase. NF: normal-fat diet; HF: high-fat diet; CO: control; CS: choline supplemented.

Fig. 5

mRNA abundance of the IGF system and activation of the AKT/mTOR pathway in the placenta at E12.5. Different diets were fed to dams from 4 weeks before timed-mating to gestational day 12.5. (A) mRNA abundance was measured by real-time PCR. (B) AKT phosphorylation and (C) mTOR-regulated proteins were assessed by western blot. Solid bars, NFCO, n = 8; shaded bars, NFCS, n = 6; open bars, HFCO, n = 7; hatched bars, HFCS, n = 6. n is the number of dams. Two placentas in each dam were included in the analysis. Values are mean ± standard error of mean (SEM); different letters indicate P < 0.05; ns: not significant. AKT: protein kinase B; IGF, insulin-like growth factor; Igf1r, insulin-like growth factor 1 receptor; mTOR, mechanistic target of rapamycin; S6, ribosomal protein S6; 4E-BP1, 4E-binding protein 1. NF: normal-fat diet; HF: high-fat diet; CO: control; CS: choline supplemented.