Excess Folic Acid Supplementation Before and During Pregnancy and Lactation Activates Fos Gene Expression and Alters Behaviors in Male Mouse Offspring

Abstract

Periconceptional folic acid (FA) supplementation is recommended to prevent neural tube defects and other birth defects. After 20 years mandate food fortification with FA, serum concentration of folate and unmetabolized FA increased significantly in the North American population. But whether excess FA intake impairs neurodevelopment and behavior is still controversial. Here, we treated mice with approximately 2.5-fold (moderate dose of FA, MFA) or 10-fold (high dose of FA, HFA) the dietary requirement of FA 1 week before mating and throughout pregnancy and lactation, and examined behaviors in adult male offspring using open field test, three-chamber sociability and social novelty test, elevated plus maze, rotarod and Morris water maze. We found that early life MFA supplementation increased long-term body weight gain in adults, elevated anxiety-like behavior, and impaired social preference, motor learning and spatial learning ability without modifying motor ability and spatial memory. In contrast, HFA supplementation only induced mild behavioral abnormality. RNA sequencing revealed that FA supplementation altered the expression of brain genes at weaning, among which Fos and related genes were significantly up-regulated in MFA mice compared with control and HFA mice. Quantitative real time-PCR (qRT-PCR) and western blots confirmed the increase of these genes. Our results suggested that FA supplementation during early life stage affected gene expression in weaning mice, and exhibited long-term impairments in adult behaviors in a dose-sensitive manner.

High Intakes of [6S]-5-Methyltetrahydrofolic Acid Compared with Folic Acid during Pregnancy Programs Central and Peripheral Mechanisms Favouring Increased Food Intake and Body Weight of Mature Female Offspring

“…Additionally, a marginally significant form effect ( p = 0.054) on ambulatory activity during the light-cycle was found that was largely driven by lower activity in 5X-MTHF compared to the 5X-FA offspring, but similar to 1X offspring; potentially contributing to their higher weight gain [ 41 ]. These results are also consistent with recent reports that show moderately high (5X) dose FA exposure throughout gestation to induce hyperactivity-like behavior in female [ 42 ] and male [ 43 ] offspring post-weaning. The body weight and food intake of the dams during pregnancy and lactation were not different between groups, nor were litter sizes or early-life growth of their offspring.…”

Folic Acid and Autism: A Systematic Review of the Current State of Knowledge

“…Similar but less severe deficits were observed in rats exposed to Ab during GST alone or only during the PRW period, suggesting the extreme sensitivity of the fetal as well as the neonatal rat brain to the deleterious effects of exposure to Ab during this period [69]. Chu D et al, (2019) [70] ICR mice Results demonstrated a change in gene expression profile in weaning mice during early life FA supplementation. Long-term behavioral effects were more evident in adult male mouse offspring in a dose-sensitive mode [70].…”

“…A lower concentration of 5-MTHF in the cell, a reduced transformation to methionine, and an altered methylation process can be the consequences of high concentrations of unmetabolized FA; in this regard, several animal studies have interestingly shown both gene-specific hypermethylation and DNA hypomethylation [77,97,98] in animals fed with higher dosages of FA, and a different grade of modulation of the global DNA methylation has been recently proposed also by Chu et al [70]. Further investigations are, however, requested in humans.…”

“…Interestingly, the authors found that behavioral abnormalities were more evident in mice fed with moderate FA doses than in those treated with higher FA doses. However, both moderate and high FA supplementation modified the cerebral gene expression in offspring at weaning, but these FA doses were not sufficient to induce autism-like behavior [70].…”

“…Chu D et al, (2019) [70] ICR mice Results demonstrated a change in gene expression profile in weaning mice during early life FA supplementation. Long-term behavioral effects were more evident in adult male mouse offspring in a dose-sensitive mode [70]. Desai A et al, (2017) [71] Rat…”