High 5MTHF, but Not Folic Acid During Pregnancy, Alters Hypothalamic Regulatory Pathways and Associates with Post-Partum Weight-Gain in Wistar Rat Mothers

Abstract

Abstract Objectives 5-methyltetrahydrofolate (5MTHF), the bioactive folate form, has been proposed an alternative supplement to folic acid (FA) due to direct cellular uptake and utilization. In North America, 5MTHF is incorporated into prenatal supplements at the equivalent high dose (1000 µg) as FA and discussion has been raised of its formation into baby formula. Our lab was the first to compare the dose (1X vs high, 5X) and form (FA vs 5MTHF) effects of folate during pregnancy on later-life metabolic health of the Wistar rat mother. Contrary to our hypothesis, 5MTHF diets, independent of dose, led to mothers with 40% greater body weight-gain and higher food intake post-birth compared to FA. The objective of this study was to identify differentially expressed genes and related hypothalamic pathways of mothers fed FA vs 5MTHF diets during pregnancy. Methods Pregnant Wistar rats were fed an AIN-93 G diet with recommended (1X, control, 2 mg/kg diet) or high (5X) FA or equimolar levels of 5MTHF. At birth, a subset of dams were terminated and RNA-seq analysis was performed in the arcuate nucleus of the hypothalamus (ARC), a key regulator of body weight and food intake, in dams fed the high FA and MTHF diets. Results Over 350 differentially expressed genes were identified in the ARC of dams fed high 5MTHF vs FA diets. Combining differential gene expression patterns with reported GO function terms and Kegg pathway analyses, four candidate genes (prolactin hormone receptor, corticotropin releasing hormone receptor, KISS1 peptide and dopamine receptor) were validated by qPCR thus far as plausible contributors to higher body weight-gain and food intake in 5MTHF dams. These genes correspond to neuroactive ligand-receptor interaction pathway (path: hsa04080), associated with metabolic diseases including leptin deficiency and genetic obesity. Other significantly enriched pathways included the retrograde endocannabinoid signalling and morphine addiction pathway. Conclusions High 5MTHF supplementation during pregnancy alters expression of central feeding regulatory pathways in the hypothalamus of the mother, potentially programming post-partum body-weight gain. 5MTHF, at the equivalent dose of FA, may not be the preferred folate form during pregnancy. Funding Sources CIHR-INMD; EP supported by NSERC-CGS D.