Moderate Folic Acid Supplementation in Pregnant Mice Results in Altered Methyl Metabolism and in Sex‐Specific Placental Transcription Changes

Abstract

Scope: Many pregnant women have higher folic acid (FA) intake due to food fortification and increased vitamin use. It is reported that diets containing five-fold higher FA than recommended for mice (5xFASD) during pregnancy resulted in methylenetetrahydrofolate reductase (MTHFR) deficiency and altered choline/methyl metabolism, with neurobehavioral abnormalities in newborns. The goal is to determine whether these changes have their origins in the placenta during embryonic development. Methods and Results: Female mice are fed control diet or 5xFASD for a month before mating and maintained on these diets until embryonic day 17.5. 5xFASD led to pseudo-MTHFR deficiency in maternal liver and altered choline/methyl metabolites in maternal plasma (increased methyltetrahydrofolate and decreased betaine). Methylation potential (S-adenosylmethionine:S-adenosylhomocysteine ratio) and glycerophosphocholine are decreased in placenta and embryonic liver. Folic acid supplemented diet results in sex-specific transcriptome profiles in placenta, with validation of dietary expression changes of 29 genes involved in angiogenesis, receptor biology or neurodevelopment, and altered methylation of the serotonin receptor 2A gene. Conclusion: Moderate increases in folate intake during pregnancy result in placental metabolic and gene expression changes, particularly in angiogenesis, which may contribute to abnormal behavior in pups. These results are relevant for determining a safe upper limit for folate intake during pregnancy.

Moderate Folic Acid Supplementation in Pregnant Mice Results in Altered Sex-Specific Gene Expression in Brain of Young Mice and Embryos

“…Detailed biometric data (maternal food consumption, maternal body weights, litter sizes, embryonic growth, and offspring body weights) have been published [ 11 , 12 ]. These results were not affected by diet.…”

“…All procedures were conducted in accordance with Canadian Council on Animal Care guidelines and approved by the RI-MUHC Animal Care Committee (AUP 3132). Mice used in this study have been described in previous publications [ 11 , 12 ]. Briefly, at weaning, female C57BL/6 mice were randomly fed CD (2 mg/kg FA, recommended amount for rodents) or 5xFASD (10 mg/kg FA) ( Table S1 ) for 4 to 5 weeks.…”

“…RNA quality, assessed by a 2100 Bioanalyzer (Agilent), had an integrity number ≥ 8.5. Data were analyzed by Transcriptome Analysis Console software (TAC 4.0.2.15; Affymetrix) using the same parameters as before, transcripts with fold changes ≥1.5 and p ≤ 0.05 [ 12 ]. The complete data set has been uploaded to the Gene Expression Omnibus database at the National Center for Biotechnology Information (GEO: GSE193355 for the P30 cortex; GEO: GSE193352 for the E17.5 cerebrum).…”

“…Downregulated hepatic MTHFR and disturbed folate and choline metabolism were identified as potential contributors. In a follow-up study to investigate the origins of the abnormal behaviors [ 12 ], we examined the impact of the same 5xFASD on embryos and placentas at embryonic day (E) 17.5. Altered methyl metabolites in the maternal plasma, placenta, and embryonic liver and changes in the placental transcriptome profile were identified [ 12 ].…”

“…In a follow-up study to investigate the origins of the abnormal behaviors [ 12 ], we examined the impact of the same 5xFASD on embryos and placentas at embryonic day (E) 17.5. Altered methyl metabolites in the maternal plasma, placenta, and embryonic liver and changes in the placental transcriptome profile were identified [ 12 ]. Many of the metabolic and molecular changes were sex-specific.…”