Abstract
BACKGROUND: Folate and choline are interconnected nutrients important for embryonic development. Genetic variants in folate enzymes, such as MTHFD1 R653Q (c.1958 G>A, rs2236225), may increase dietary choline requirements. OBJECTIVES: To evaluate the impact of phosphatidylcholine or betaine supplementation on embryonic development and maternal choline metabolism in the Mthfd1S(+/-) mouse model for the MTHFD1 653QQ genotype. METHODS: Female Mthfd1S(+/+) (wild type [WT]) and Mthfd1S(+/-) (heterozygous [HET]) mice were fed amino acid-defined control (Ctrl), phosphatidylcholine-supplemented (PtdCho), or betaine-supplemented (BTN) diets for 4-6 wk before mating and during pregnancy (18-33 mice/group). Ctrl contained 2.5 g choline bitartrate/kg diet (based on AIN-93G). Supplemented diets contained additional phosphatidylcholine or betaine to obtain the molar equivalent of 3 times the free choline of Ctrl. Embryos were examined for anatomical developmental delays and morphological defects at embryonic day 10.5. One-carbon metabolites (homocysteine, choline, betaine, methionine, cystathionine, S-adenosylmethionine, S-adenosylhomocysteine) were measured in maternal plasma and liver by liquid chromatography-mass spectrometry (LC-MS/MS). The MTHFR protein in maternal liver was assessed by Western blot. Data were analyzed by binary logistic regression or 2-way analysis of variance. RESULTS: PtdCho increased developmental delays, compared with Ctrl, in litters of WT (170%) and HET (125%) mothers (P(diet) < 0.05). BTN decreased delays 53% compared with Ctrl in HET mother's litters (P(diet (HET)) < 0.05). Defects decreased 71% in BTN-fed HET mother's litters compared to WT (P < 0.05). BTN increased total pregnancy losses 360% (P(diet) < 0.01); PtdCho had no effect. Both diets decreased maternal plasma homocysteine (30-50%, P(diet) < 0.05), increased liver BTN (220-290%, P(diet) < 0.0001), and decreased S-adenosylmethionine/S-adenosylhomocysteine (WT: 20-30%, HET: 48-61%, P(diet) < 0.05). MTHFR protein expression decreased 25% in PtdCho maternal liver (P(diet) < 0.01). CONCLUSIONS: Phosphatidylcholine and betaine supplementation had contrasting effects on reproductive outcomes. PtdCho increased developmental delays. BTN reduced delays and defects in the Mthfd1S(+/-) mouse model, but may impair the establishment of pregnancy. The timing, form, and dosage of choline supplementation may be important and require further investigation.