High Gestational Folic Acid Supplementation Alters Expression of Imprinted and Candidate Autism Susceptibility Genes in a sex-Specific Manner in Mouse Offspring

Risk of Excess Maternal Folic Acid Supplementation in Offspring

Folate, also known as vitamin B9, facilitates the transfer of methyl groups among molecules, which is crucial for amino acid metabolism and nucleotide synthesis. Adequate maternal folate supplementation has been widely acknowledged for its pivotal role in promoting cell proliferation and preventing neural tube defects. However, in the post-fortification era, there has been a rising concern regarding an excess maternal intake of folic acid (FA), the synthetic form of folate. In this review, we focused on recent advancements in understanding the influence of excess maternal FA intake on offspring. For human studies, we summarized findings from clinical trials investigating the effects of periconceptional FA intake on neurodevelopment and molecular-level changes in offspring. For studies using mouse models, we compiled the impact of high maternal FA supplementation on gene expression and behavioral changes in offspring. In summary, excessive maternal folate intake could potentially have adverse effects on offspring. Overall, we highlighted concerns regarding elevated maternal folate status in the population, providing a comprehensive perspective on the potential adverse effects of excessive maternal FA supplementation on offspring.

Prenatal folate deficiency impairs sociability and memory/recognition in mice offspring

Folate is essential for the normal growth and development of the fetus. Folic acid supplementation during the fetal period affects postnatal brain development and reduces the incidence of mental disorders in animal and human studies. However, the association between folate deficiency (FD) during pregnancy and developmental disorders in children remains poorly understood. In this study, we investigated whether prenatal FD is associated with neurodevelopmental disorders in offspring. ICR mice were fed a control diet (2 mg folic acid/kg diet) or a folate-deficient diet (0.3 mg folic acid/kg diet) from embryonic day 1 until parturition. We evaluated locomotor activity, anxiety, grooming, sociability and learning memory in male offspring at 7-10 weeks of age. No differences were found in locomotor activity or anxiety in the open field test, nor in grooming time in the self-grooming test. However, sociability, spatial memory, and novel object recognition were impaired in the FD mice compared with control offspring. Furthermore, we measured protein expression levels of the NMDA and AMPA receptors, as well as PSD-95 and the GABA-synthesizing enzymes GAD65/67 in the frontal cortex and hippocampus. In FD mice, expression levels of AMPA receptor 1 and PSD-95 in both regions were reduced compared with control mice. Moreover, NMDA receptor subunit 2B and GAD65/67 were significantly downregulated in the frontal cortex of prenatal FD mice compared with the controls. Collectively, these findings suggest that prenatal FD causes behavioral deficits together with a reduction in synaptic protein levels in the frontal cortex and hippocampus.

Uncovering the Hidden Dangers and Molecular Mechanisms of Excess Folate: A Narrative Review

This review delves into the intricate relationship between excess folate (vitamin B9) intake, especially its synthetic form, namely, folic acid, and its implications on health and disease. While folate plays a pivotal role in the one-carbon cycle, which is essential for DNA synthesis, repair, and methylation, concerns arise about its excessive intake. The literature underscores potential deleterious effects, such as an increased risk of carcinogenesis; disruption in DNA methylation; and impacts on embryogenesis, pregnancy outcomes, neurodevelopment, and disease risk. Notably, these consequences stretch beyond the immediate effects, potentially influencing future generations through epigenetic reprogramming. The molecular mechanisms underlying these effects were examined, including altered one-carbon metabolism, the accumulation of unmetabolized folic acid, vitamin-B12-dependent mechanisms, altered methylation patterns, and interactions with critical receptors and signaling pathways. Furthermore, differences in the effects and mechanisms mediated by folic acid compared with natural folate are highlighted. Given the widespread folic acid supplementation, it is imperative to further research its optimal intake levels and the molecular pathways impacted by its excessive intake, ensuring the health and well-being of the global population.

Cross-Talk between miRNAs from the Dlk1-Dio3 Locus and Histone Methylation to Protect Male Cerebellum from Methyl Donor Deficiency

SCOPE

Disruption of the one carbon metabolism during development, i.e., following a gestational vitamin B9 and B12 deficiencies, is involved in birth defects and brain development delay. Using a rat nutritional model, consisting of pups born to dams fed a vitamin B9 and B12 deficient diet (MDD), the study previously reports molecular and cellular alterations in the brain, in a sex dependent manner, with females being more affected than males. The study hypothesizes that epigenetic modifications could participate in the sex differences is observed.

METHODS AND RESULTS

The study investigates lysine methylation of histones and expression of microRNAs in the cerebellum of MDD male and female pups. The study reports a differential regulation of H3K36Me2 and H4K20Me3 between males and females, in response to MDD. Moreover, distinct regulation of Kmt5b and Kdm2a expression by miR-134-5p and miR-369-5p from the Dlk1-Dio3 locus, contributes to the maintenance of expression of genes involved in synaptic plasticity.

CONCLUSION

These results could explain the neuroprotection to MDD that male pups display. The work will contribute to the understanding of the consequences of vitamin starvation on brain development, as well as how the epigenome is affected by one carbon metabolism disruption.

Prenatal folic acid supplement/dietary folate and cognitive development in 4-year-old offspring from the Japan Environment and Children's Study

We evaluated the association between maternal prenatal folic acid supplement use/dietary folate intake and cognitive development in 4-year-old offspring (N = 3445) using data from the Japan Environment and Children's Study. Cognitive development was evaluated using the Kyoto Scale of Psychological Development 2001. Multiple regression analysis revealed that offspring of mothers who started using folic acid supplements pre-conception had a significantly higher language-social developmental quotient (DQ) (partial regression coefficient 1.981, 95% confidence interval 0.091 to 3.872) than offspring of mothers who did not use such supplements at any time throughout their pregnancy (non-users). Offspring of mothers who started using folic acid supplements within 12 weeks of gestation had a significantly higher cognitive-adaptive (1.489, 0.312 to 2.667) and language-social (1.873, 0.586 to 3.159) DQ than offspring of non-users. Regarding daily dietary folate intake from preconception to early pregnancy, multiple regression analysis revealed that there was no significant association with any DQ area in the 200 to < 400 µg and the ≥ 400 µg groups compared with the < 200 µg group. Maternal prenatal folic acid supplementation starting within 12 weeks of gestation (but not adequate dietary folate intake from preconception to early pregnancy) is positively associated with cognitive development in 4-year-old offspring.

Folate regulates RNA m5C modification and translation in neural stem cells

BACKGROUND

Folate is an essential B-group vitamin and a key methyl donor with important biological functions including DNA methylation regulation. Normal neurodevelopment and physiology are sensitive to the cellular folate levels. Either deficiency or excess of folate may lead to neurological disorders. Recently, folate has been linked to tRNA cytosine-5 methylation (m⁵C) and translation in mammalian mitochondria. However, the influence of folate intake on neuronal mRNA m⁵C modification and translation remains largely unknown. Here, we provide transcriptome-wide landscapes of m⁵C modification in poly(A)-enriched RNAs together with mRNA transcription and translation profiles for mouse neural stem cells (NSCs) cultured in three different concentrations of folate.

RESULTS

NSCs cultured in three different concentrations of folate showed distinct mRNA methylation profiles. Despite uncovering only a few differentially expressed genes, hundreds of differentially translated genes were identified in NSCs with folate deficiency or supplementation. The differentially translated genes induced by low folate are associated with cytoplasmic translation and mitochondrial function, while the differentially translated genes induced by high folate are associated with increased neural stem cell proliferation. Interestingly, compared to total mRNAs, polysome mRNAs contained high levels of m⁵C. Furthermore, an integrative analysis indicated a transcript-specific relationship between RNA m⁵C methylation and mRNA translation efficiency.

CONCLUSIONS

Altogether, our study reports a transcriptome-wide influence of folate on mRNA m⁵C methylation and translation in NSCs and reveals a potential link between mRNA m⁵C methylation and mRNA translation.

Paternal preconceptional diet enriched with n-3 polyunsaturated fatty acids affects offspring brain function in mice

Recent studies demonstrate that paternal nutrition prior to conception may determine offspring development and health through epigenetic modification. This study aims to investigate the effects of paternal supplementation of n-3 polyunsaturated fatty acids (n-3 PUFAs) on the brain development and function, and associated gene imprinting in the offspring. Three to four-week-old male C57BL/6J mice (founder) were fed with an n-3 PUFA-deficient diet (n-3 D), and two n-3 PUFA supplementation diets – a normal n-3 PUFA content diet (n-3 N) and a high n-3 PUFA content diet (n-3 H) for 12 weeks. Then they were mated to 10-week-old virgin female C57BL/6J mice to generate the offspring. The results showed that paternal n-3 PUFA supplementation in preconception reduced the anxiety- and depressive-like behavior, and improved sociability, learning and memory in the offspring, along with increased synaptic number, upregulated expressions of neuron specific enolase, myelin basic protein, glial fibrillary acidic protein, brain-derived neurotrophic factor in the hippocampus and cerebral cortex, and altered expressions of genes associated with mitochondria biogenesis, fusion, fission and autophagy. Furthermore, with paternal n-3 PUFA supplementation, the expression of imprinted gene Snrpn was downregulated both in testes of the founder mice and their offspring, but upregulated in the cerebral cortex and hippocampus, with altered DNA methylation in its differentially methylated region. The data suggest that higher paternal intake of n-3 PUFAs in preconception may help to maintain optimal brain development and function in the offspring, and further raise the possibility of paternal nutritional intervention for mental health issues in subsequent generations.

The Impact of Maternal Folates on Brain Development and Function after Birth

Folate is vital for biological processes within the body, including DNA synthesis, DNA repair, and methylation reactions that metabolize homocysteine. The role of folate is particularly important in pregnancy, where there is rapid cellular and tissue growth. Maternal folate deficiencies secondary to inadequate dietary supplementation are known to produce defects in the neural tube and spinal cord, yet the exact mechanism of folate in neurodevelopment is unknown. The consequences of maternal folate deficiency on offspring brain development and function beyond gestation are not well defined. The objective of this review is to investigate the role of folate deficiency in offspring neurodevelopment, and the complications that arise post-gestation. This was accomplished through a comprehensive review of the data presented in both clinical and preclinical studies. Evidence supports that folate deficiency is associated with altered offspring neurodevelopment, including smaller total brain volume, altered cortical thickness and cerebral white matter, altered neurogenesis, and neuronal apoptosis. Some of these changes have been associated with altered brain function in offspring with memory, motor function, language skills, and psychological issues. This review of literature also presents potential mechanisms of folate deficiency in neurodevelopment with altered metabolism, neuroinflammation, epigenetic modification through DNA methylation, and a genetic deficiency in one-carbon metabolism.

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

Folic acid has been identified to be integral in rapid tissue growth and cell division during fetal development. Different studies indicate folic acid’s importance in improving childhood behavioral outcomes and underline its role as a modifiable risk factor for autism spectrum disorders. The aim of this systematic review is to both elucidate the potential role of folic acid in autism spectrum disorders and to investigate the mechanisms involved. Studies have pointed out a potential beneficial effect of prenatal folic acid maternal supplementation (600 µg) on the risk of autism spectrum disorder onset, but opposite results have been reported as well. Folic acid and/or folinic acid supplementation in autism spectrum disorder diagnosed children has led to improvements, both in some neurologic and behavioral symptoms and in the concentration of one-carbon metabolites. Several authors report an increased frequency of serum auto-antibodies against folate receptor alpha (FRAA) in autism spectrum disorder children. Furthermore, methylene tetrahydrofolate reductase (MTHFR) polymorphisms showed a significant influence on ASD risk. More clinical trials, with a clear study design, with larger sample sizes and longer observation periods are necessary to be carried out to better evaluate the potential protective role of folic acid in autism spectrum disorder risk.

The Use of Lower or Higher Than Recommended Doses of Folic Acid Supplements during Pregnancy Is Associated with Child Attentional Dysfunction at 4-5 Years of Age in the INMA Project

We assessed the association between the use of lower- and higher-than-recommended doses of folic acid supplements (FAs) during pregnancy and attentional function in boys and girls at age of 4–5. We analyzed data from 1329 mother-child pairs from the mother-child cohort INfancia y Medio Ambiente Project (INMA) study. Information on FAs use during pregnancy was collected in personal interviews at weeks 12 and 30, and categorized in <400, 400–999 (recommended dose), and ≥1000 μg/day. Child attentional function was assessed by Conners’ Kiddie Continuous Performance Test. Multivariable regression analyses were used to estimate incidence rate ratios (IRR) and beta coefficients with 95% confidence intervals (CI). Compared to recommended FAs doses, the periconceptional use of <400 and ≥1000 μg/day was associated with higher risk of omission errors—IRR = 1.14 (95% CI: 1.01; 1.29) and IRR = 1.16 (95% CI: 1.02; 1.33), respectively. The use of FAs < 400 μg/day and ≥1000 μg/day was significantly associated with deficits of attentional function only in boys. FAs use < 400 μg/day was associated with higher omission errors with IRR = 1.22 and increased hit reaction time (HRT) β = 34.36, and FAs use ≥ 1000 μg/day was associated with increased HRT β = 33.18 and HRT standard error β = 3.31. The periconceptional use of FAs below or above the recommended doses is associated with deficits of attentional function in children at age of 4–5, particularly in boys.

Acute high folic acid treatment in SH-SY5Y cells with and without MTHFR function leads to gene expression changes in epigenetic modifying enzymes, changes in epigenetic marks, and changes in dendritic spine densities

Epigenetics are known to be involved in various disorders, including neurobiological disorders like autism. Dietary factors such as folic acid can affect epigenetic marks using methylenetetrahydrofolate reductase (MTHFR) to metabolize folic acid to a one-carbon methyl group. As MTHFR mutations are frequent, it is curious as to whether excess folic acid, with or without functioning MTHFR, could affect gene expression, epigenetics, and neuromorphology. Here, we investigated gene expression and activity of epigenetic modifying enzymes, genome-wide DNA methylation, histone 3 modifications, and dendritic spine densities in SH-SY5Y cells with or without a knockdown of MTHFR and with or without an excess of folic acid. We found alterations to gene expression of epigenetic modifying enzymes, including those associated with disorders like autism. Grouping the epigenetic modifying enzymes by function indicated that gene expression was widely affected for genes that code for enzymes affecting DNA methylation, histone acetylation, histone methylation, histone phosphorylation, and histone ubiquitination when excess folic acid treatment occurred with or without the knockdown of MTHFR. MTHFR was significantly reduced upon excess folic acid treatment whether MTHFR was knocked-down or not. Further, methyl-CpG binding protein 2 expression was significantly decreased with excess folic acid treatment with and without proper MTHFR expression. Global DNA methylation decreased due to the knockdown alone while global hydroxymethylated DNA increased due to the knockdown alone. TET2 expression significantly increased with the MTHFR knockdown alone. Excess folic acid alone induced a decrease in TET3 expression. Excess folic acid induced an increase in dendritic spines without the MTHFR knockdown, but folic acid induced a decrease in dendritic spines when MTHFR was knocked-down. The knockdown alone also increased the dendritic spines significantly. Histone 3 acetylation at lysine 18 was significantly increased when excess folic acid was applied to cells with the MTHFR knockdown, as was histone 3 phosphorylation at serine 10. Broadly, our results indicate that excess folic acid, even with functioning MTHFR, could have detrimental effects on cells.

Novel sex-specific influence of parental factors on small-for-gestational-age newborns

Since fetal programming is sex-specific, there may also be sex-specific in parental influences on newborn birth weight. We aimed to investigate the influence of parental factors on small-for-gestational-age (SGA) infants of different sexes. Based on a pre-pregnancy cohort, multivariate logistic regression was used. 2275 couples were included for analysis. Significant associations were observed among paternal height, pre-pregnancy body mass index (BMI), and SGA in male infants; among maternal height, pre-pregnancy BMI, and SGA in female infants, and among other maternal factors and SGA in both male and female infants. Such sex specificity may be related to genetic, epigenetic, or hormonal influences between parents and infants. In conclusion, there is a sex specificity in the effect of parental height and pre-pregnancy BMI on SGA. The data suggest that future studies on infants should consider the sex-specific differences between the effects of genetic or environmental factors and infants.

Gut microbiota on gender bias in autism spectrum disorder

Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder. Its three core symptoms are social communication disorder, communication disorder, narrow interest and stereotyped repetitive behavior. The proportion of male and female autistic patients is 4:1. Many researchers have studied this phenomenon, but the mechanism is still unclear. This review mainly discusses the related mechanism from the perspective of gut microbiota and introduces the influence of gut microbiota on the difference of ASD between men and women, as well as how gut microbiota may affect the gender dimorphism of ASD through metabolite of microbiota, immunity, and genetics, which provide some useful information for those who are interested in this research and find more gender-specific treatment for autistic men and women.

Moderate Folic Acid Supplementation in Pregnant Mice Results in Behavioral Alterations in Offspring with Sex-Specific Changes in Methyl Metabolism

Fifteen to 20% of pregnant women may exceed the recommended intake of folic acid (FA) by more than four-fold. This excess could compromise neurocognitive and motor development in offspring. Here, we explored the impact of an FA-supplemented diet (5× FASD, containing five-fold higher FA than recommended) during pregnancy on brain function in murine offspring, and elucidated mechanistic changes. We placed female C57BL/6 mice for one month on control diets or 5× FASD before mating. Diets were maintained throughout pregnancy and lactation. Behavioural tests were conducted on 3-week-old pups. Pups and mothers were sacrificed at weaning. Brains and livers were collected to examine choline/methyl metabolites and immunoreactive methylenetetrahydrofolate reductase (MTHFR). 5× FASD led to hyperactivity-like behavior and memory impairment in 3-week-old pups of both sexes. Reduced MTHFR protein in the livers of FASD mothers and male pups resulted in choline/methyl metabolite disruptions in offspring liver (decreased betaine) and brain (decreased glycerophosphocholine and sphingomyelin in male pups, and decreased phosphatidylcholine in both sexes). These results indicate that moderate folate supplementation downregulates MTHFR and alters choline/methyl metabolism, contributing to neurobehavioral alterations. Our findings support the negative impact of high FA on brain development, and may lead to improved guidelines on optimal folate levels during pregnancy.

Maternal blood folate status during early pregnancy and occurrence of autism spectrum disorder in offspring: a study of 62 serum biomarkers

BACKGROUND

Autism spectrum disorder (ASD) evolves from an interplay between genetic and environmental factors during prenatal development. Since identifying maternal biomarkers associated with ASD risk in offspring during early pregnancy might result in new strategies for intervention, we investigated maternal metabolic biomarkers in relation to occurrence of ASD in offspring using both univariate logistic regression and multivariate network analysis.

METHODS

Serum samples from 100 women with an offspring diagnosed with ASD and 100 matched control women with typically developing offspring were collected at week 14 of pregnancy. Concentrations of 62 metabolic biomarkers were determined, including amino acids, vitamins (A, B, D, E, and K), and biomarkers related to folate (vitamin B₉) metabolism, lifestyle factors, as well as C-reactive protein (CRP), the kynurenine-tryptophan ratio (KTR), and neopterin as markers of inflammation and immune activation.

RESULTS

We found weak evidence for a positive association between higher maternal serum concentrations of folate and increased occurrence of ASD (OR per 1 SD increase: 1.70, 95% CI 1.22-2.37, FDR adjusted P = 0.07). Multivariate network analysis confirmed expected internal biochemical relations between the biomarkers. Neither inflammation markers nor vitamin D₃ levels, all hypothesized to be involved in ASD etiology, displayed associations with ASD occurrence in the offspring.

CONCLUSIONS

Our findings suggest that high maternal serum folate status during early pregnancy may be associated with the occurrence of ASD in offspring. No inference about physiological mechanisms behind this observation can be made at the present time because blood folate levels may have complex relations with nutritional intake, the cellular folate status and status of other B-vitamins. Therefore, further investigations, which may clarify the potential role and mechanisms of maternal blood folate status in ASD risk and the interplay with other potential risk factors, in larger materials are warranted.

Effect of supplementation with methyl-donor nutrients on neurodevelopment and cognition: considerations for future research

Pregnancy represents a critical period in fetal development, such that the prenatal environment can, in part, establish a lifelong trajectory of health or disease for the offspring. Poor nutrition (macro- or micronutrient deficiencies) can adversely affect brain development and significantly increase offspring risk for metabolic and neurological disease development. The concentration of dietary methyl-donor nutrients is known to alter DNA methylation in the brain, and alterations in DNA methylation can have long-lasting effects on gene expression and neuronal function. The decreased availability of methyl-donor nutrients to the developing fetus in models of poor maternal nutrition is one mechanism hypothesized to link maternal malnutrition and disease risk in offspring. Animal studies indicate that supplementation of both maternal and postnatal (early- and later-life) diets with methyl-donor nutrients can attenuate disease risk in offspring; however, clinical research is more equivocal. The objective of this review is to summarize how specific methyl-donor nutrient deficiencies and excesses during pre- and postnatal life alter neurodevelopment and cognition. Emphasis is placed on reviewing the current literature, highlighting challenges within nutrient supplementation research, and considering potential strategies to ensure robust findings in future studies.

A 2x folic acid treatment affects epigenetics and dendritic spine densities in SHSY5Y cells

Many diseases are now associated with aberrant epigenetics and gene expression changes. Epigenetics can be modified by factors like diet. One dietary factor, folic acid, is consumed in various forms including supplements, energy drinks, and fortified grains. It was hypothesized high levels of folic acid would affect gene expression and enzyme activity of chromatin modifying enzymes as well as dendritic spine densities in a commonly utilized neuron model, the SHSY5Y cell. Decreased MBD2 and MECP2 were discovered upon treatment of SHSY5Y cells with a 2x folic acid dose. Corresponding decreases in dendritic spines were apparent in the 2x folic acid treated cells as well. Activity of DNMTs and H3K4 HMTs was altered. Further, H3K4me1, H3K4me3, H3K9Ac, and global DNA methylation were decreased in the 2x folic acid treated cells. Further studies are warranted to determine if the effects of excess folic acid are detrimental to organismal physiology.

•

The 2x folic acid treatment in SHSY5Y cells induces a significant decrease in MBD2 and MECP2 mRNA expression.

•

The excess folic acid also causes a significant increase in dendritic spines in SHSY5Y cells.

•

The 2x folic acid treatment increases DNMT activity and significantly decreases H3K4 HMT activity in SHSY5Y cells.

•

These findings align with some of those seen in autism spectrum disorders.

Nutritional Supplements During Gestation and Autism Spectrum Disorder: What Do We Really Know and How Far Have We Gone?

Nutritional interventions are gaining remarkable attention as complementary management options for autism. Our aim is to provide literature data about the impact of the administration of dietary supplements during pregnancy on the risk of autism spectrum disorder in the offspring. A comprehensive search was undertaken by 2 reviewers independently using PubMed as the medical database source. Prospective clinical and experimental studies were considered and no year-of-publication restriction was placed. We were able to identify 4 basic (conducted in rodents) and 3 clinical research papers fulfilling our selection criteria. Supplements studied included folic acid, iron, multivitamins, choline, vitamin D, and docosahexaenoic acid. Choline and folic acid had a significant impact on the expression of autism-related genes. However, from a clinical point of view, prenatal folate administration did not reduce the risk of autism. Similarly, iron had no significant impact, while the use of multivitamins in moderate frequency had a protective effect. The use of vitamin D and docosahexaenoic acid during gestation decreased the incidence of autism in animal models. In conclusion, available data are controversial and cannot change current routine practice. More large-scale prospective studies are needed to identify the real effect of nutritional supplements and also optimize their administration.Key teaching pointsMultivitamins use during pregnancy can exert a protective effect on the risk of autism, although depending on the frequency of use. Nevertheless, prenatal iron and folate were not shown to have any significant impact.Research based on animal models showed that choline and folic acid can have a significant impact on the expression of autism-related genes in a sex-specific manner.Furthermore, the use of vitamin D and docosahexaenoic acid during gestation seem to decrease the incidence of autism in animal offspring.In the future, more clinical, large-scale prospective and methodologically homogenous clinical studies are needed to further investigate the effect of the periconceptional use of nutritional supplements on autism risk.

The Importance of Maternal Folate Status for Brain Development and Function of Offspring

The importance of an adequate periconceptional maternal folate status to prevent fetal neural tube defects has been well demonstrated and resulted in the recommendation for women to use folic acid supplements during the periconception period. The importance of maternal folate status for offspring neurodevelopment and brain health is less well described. We reviewed the current evidence linking maternal folate status before conception and during pregnancy with neurodevelopment and cognition of the offspring. We discuss both animal and human studies. Preclinical research revealed the importance of maternal folate status for several key processes required for normal neurodevelopment and brain functioning in the offspring, including DNA synthesis, regulation of gene expression, synthesis of phospholipids and neurotransmitters, and maintenance of healthy plasma homocysteine concentrations. Human observational studies are inconclusive; about half have shown a positive association between maternal folate status and cognitive performance of offspring. Whereas some studies suggest a positive association between maternal folate intake and cognition of offspring during childhood, data from interventional studies are too limited to conclude that there is a direct effect. Future preclinical studies are needed to help us characterize the behavioral effects, understand the underlying mechanisms, and to establish an optimal dosage and time window of folate supplementation. Moreover, more conclusive data from well-designed human observational studies and randomized controlled trials are needed to determine whether current recommendations for folic acid supplementation during pregnancy cover the needs for normal cognitive development in the offspring.

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

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.

A folic acid-enriched diet attenuates prostate involution in response to androgen deprivation

BACKGROUND

Serum folate concentrations in the United States have risen since dietary folic acid fortification was first mandated in 1998. Although maternal folic acid offers protection against neural tube defects in conceptuses, its impact on other organ systems and life stages have not been fully examined. Here, we used a mouse model to investigate the impact of a Folic acid (FA) enriched diet on prostate homeostasis and response to androgen deprivation.

METHODS

Male mice were fed a control diet (4 mg FA/kg feed) or a folic acid supplemented diet (24 mg FA/kg feed) beginning at conception and continuing through early adulthood, when mice were castrated.

RESULTS

We made the surprising observation that dietary FA supplementation confers partial resistance to castration-mediated prostate involution. At 3, 10, and 14 days post-castration, FA enriched diet fed mice had larger prostates as assessed by wet weight, taller prostatic luminal epithelial cells, and more abundant RNAs encoding prostate secretory proteins than castrated control diet fed mice. Diet did not significantly affect prostate weights of intact mice or serum testosterone concentrations of castrated mice. RNA-Seq analysis revealed that the FA enriched diet was associated with a unique prostate gene expression signature, affecting several signaling and metabolic pathways.

CONCLUSIONS

Continuous exposure to a FA enriched diet slows prostate involution in response to androgen deprivation. Prostates from FA diet mice have increased secretory gene expression and increased luminal cell heights. The influence of dietary FA supplementation on the prostate response to androgen deprivation raises a future need to consider how dietary folic acid supplementation affects efficacy of androgen-reducing therapies for treating prostate disease.

Periconceptional folic acid supplementation and sex difference in prevention of neural tube defects and their subtypes in China: results from a large prospective cohort study

BACKGROUND

Folic acid (FA) supplementation is known to prevent neural tube defects (NTDs). We examined whether this preventive effect differs by the sex of the infant.

METHODS

Data were gathered from a large population-based cohort study in China that evaluated the effects of FA supplementation on NTDs. All births at 20 complete gestational weeks, including live births, stillbirths, and pregnancy terminations, and all NTDs, regardless of gestational age, were recorded. In a northern China province, a total of 30,801 singleton live births to women whose use of FA supplements during the first trimester was known at the time were included in the study. The birth prevalence of NTDs was classified by sex, subtype, and maternal FA supplementation. Male to female rate ratios [RR] and their 95% confidence intervals [CI] were calculated.

RESULTS

A total of 106 NTDs cases were recorded. The overall prevalence of NTDs was 2.5‰ among males and 4.4‰ among females; NTDs were less prevalent among males than among females (RR, 0.58; 95% CI, 0.54-0.63). There was a higher prevalence of anencephaly (RR, 0.34; 95% CI, 0.27-0.43) and spina bifida (RR, 0.73; 95% CI, 0.63-0.84) among females. However, FA supplementation led to significantly greater decreases in the rates of anencephaly (4.8‰) and total NTDs (7.6‰) in females than in males (1.6‰ and 2.8‰, respectively).

CONCLUSIONS

FA supplementation successfully reduces the prevalence of NTDs in both male and female infants, although we found a significantly greater decrease in anencephaly and total NTDs in females than in males. How the protective effects of FA supplementation affect the sexes differently needs to be studied further.

Hippocampus-dependent memory and allele-specific gene expression in adult offspring of alcohol-consuming dams after neonatal treatment with thyroxin or metformin

Fetal alcohol spectrum disorder (FASD), the result of fetal alcohol exposure (FAE), affects 2-11% of children worldwide, with no effective treatments. Hippocampus-based learning and memory deficits are key symptoms of FASD. Our previous studies show hypothyroxinemia and hyperglycemia of the alcohol-consuming pregnant rat, which likely affects fetal neurodevelopment. We administered vehicle, thyroxine (T4) or metformin to neonatal rats post FAE and rats were tested in the hippocampus-dependent contextual fear-conditioning paradigm in adulthood. Both T4 and metformin alleviated contextual fear memory deficit induced by FAE, and reversed the hippocampal expression changes in the thyroid hormone-inactivating enzyme, deiodinase-III (Dio3) and insulin-like growth factor 2 (Igf2), genes that are known to modulate memory processes. Neonatal T4 restored maternal allelic expressions of the imprinted Dio3 and Igf2 in the adult male hippocampus, while metformin restored FAE-caused changes in Igf2 expression only. The decreased hippocampal expression of DNA methyltransferase 1 (Dnmt1) that maintains the imprinting of Dio3 and Igf2 during development was normalized by both treatments. Administering Dnmt1 inhibitor to control neonates resulted in FAE-like deficits in fear memory and hippocampal allele-specific expression of Igf2, which were reversed by metformin. We propose that neonatal administration of T4 and metformin post FAE affect memory via elevating Dnmt1 and consequently normalizing hippocampal Dio3 and Igf2 expressions in the adult offspring. The present results indicate that T4 and metformin, administered during the neonatal period that is equivalent to the third trimester of human pregnancy, are potential treatments for FASD and conceivably for other neurodevelopmental disorders with cognitive deficits.

Maternal Multivitamin Intake, Plasma Folate and Vitamin B12 Levels and Autism Spectrum Disorder Risk in Offspring

BACKGROUND

To examine the prospective association between multivitamin supplementation during pregnancy and biomarker measures of maternal plasma folate and vitamin B₁₂ levels at birth and child's Autism Spectrum Disorder (ASD) risk.

METHODS

This report included 1257 mother-child pairs, who were recruited at birth and prospectively followed through childhood at the Boston Medical Center. ASD was defined from diagnostic codes in electronic medical records. Maternal multivitamin supplementation was assessed via questionnaire interview; maternal plasma folate and B₁₂ were measured from samples taken 2-3 days after birth.

RESULTS

Moderate (3-5 times/week) self-reported supplementation during pregnancy was associated with decreased risk of ASD, consistent with previous findings. Using this as the reference group, low (≤2 times/week) and high (>5 times/week) supplementation was associated with increased risk of ASD. Very high levels of maternal plasma folate at birth (≥60.3 nmol/L) had 2.5 times increased risk of ASD [95% confidence interval (CI) 1.3, 4.6] compared to folate levels in the middle 80th percentile, after adjusting for covariates including MTHFR genotype. Similarly, very high B₁₂ (≥536.8 pmol/L) showed 2.5 times increased risk (95% CI 1.4, 4.5).

CONCLUSION

There was a 'U shaped' relationship between maternal multivitamin supplementation frequency and ASD risk. Extremely high maternal plasma folate and B₁₂ levels at birth were associated with ASD risk. This hypothesis-generating study does not question the importance of consuming adequate folic acid and vitamin B₁₂ during pregnancy; rather, raises new questions about the impact of extremely elevated levels of plasma folate and B₁₂ exposure in-utero on early brain development.

Effect of maternal high dosages of folic acid supplements on neurocognitive development in children at 4-5 y of age: the prospective birth cohort Infancia y Medio Ambiente (INMA) study

Background: The benefits of the use of folic acid supplements (FASs) during the periconception period to prevent neural tube defects and to ensure normal brain development in offspring are well known. There is concern, however, about the long-term effects of the maternal use of high dosages of FASs that exceed the Tolerable Upper Intake Level (UL) (≥1000 μg/d) on child neurocognitive outcomes.Objective: The objective of the study was to examine the association between the use of high dosages of FASs during pregnancy and child neuropsychological development at ages 4-5 y.Design: The multicenter prospective mother-child cohort study, the Infancia y Medio Ambiente (INMA) Project, was conducted in 4 regions of Spain: Asturias, Sabadell, Gipuzkoa, and Valencia. Pregnant women were recruited between 2003 and 2008. Data on 1682 mother-child pairs were included in the final analyses. The pregnant women completed an interviewer-administered questionnaire that was validated to estimate typical dietary folate intake and the use of FASs at 10-13 and 28-32 wk of gestation. Neuropsychological development scores at 4-5 y of age were estimated with the use of the McCarthy Scales of Children's Abilities. Multiple linear regression and meta-analysis were used to obtain combined-effect estimates.Results: During the periconception period, one-third of the women (n = 502) took FAS dosages ≥1000 μg/d. The use of FAS dosages ≥1000 μg/d in this period was negatively associated with several neuropsychological outcomes scores in children: global verbal (β = -2.49; 95% CI: -4.71, -0.27), verbal memory (β = -3.59; 95% CI: -6.95, -0.23), cognitive function of posterior cortex (β = -2.31; 95% CI: -4.45, -0.18), and cognitive function of left posterior cortex (β = -3.26; 95% CI: -5.51, -1.01).Conclusions: The use of FAS dosages exceeding the UL (≥1000 μg/d) during the periconception period was associated with lower levels of cognitive development in children aged 4-5 y. The use of FAS dosages ≥1000 μg/d during pregnancy should be monitored and prevented as much as possible, unless medically prescribed.

The Evaluation of Folic Acid-Deficient or Folic Acid-Supplemented Diet in the Gestational Phase of Female Rats and in Their Adult Offspring Subjected to an Animal Model of Schizophrenia

Although folic acid (FA) supplementation is known to influence numerous physiological functions, especially during pregnancy, little is known about its direct effects on the mothers' health. However, this vitamin is essential for the health of the mother and for the normal growth and development of the fetus. Thus, the aim of this study was (1) to evaluate the cognitive effects and biochemical markers produced by the AIN-93 diet (control), the AIN-93 diet supplemented with different doses of FA (5, 10, and 50 mg/kg), and a FA-deficient diet during pregnancy and lactation in female mother rats (dams) and (2) to evaluate the effect of maternal diets on inflammatory parameters in the adult offspring which were subjected to an animal model of schizophrenia (SZ) induced by ketamine (Ket). Our study demonstrated through the Y-maze test that rats subjected to the FA-deficient diet showed significant deficits in spatial memory, while animals supplemented with FA (5 and 10 mg/kg) showed no deficit in spatial memory. Our results also suggest that the rats subjected to the FA-deficient diet had increased levels of carbonylated proteins in the frontal cortex and hippocampus and also increased plasma levels of homocysteine (Hcy). Folate was able to prevent cognitive impairments in the rats supplemented with FA (5 and 10 mg/kg), data which may be attributed to the antioxidant effect of the vitamin. Moreover, FA prevented protein damage and elevations in Hcy levels in the rats subjected to different doses of this vitamin (5, 10, and 50 mg/kg). We verified a significant increase of the anti-inflammatory cytokine (interleukin-4 (IL-4)) and a reduction in the plasma levels of proinflammatory cytokines (interleukin-6 (IL-6)) and TNF-α) in the dams that were subjected to the diets supplemented with FA (5, 10, and 50 mg/kg), showing the possible anti-inflammatory effects of FA during pregnancy and lactation. In general, we also found that in the adult offspring that were subjected to an animal model of SZ, FA had a protective effect in relation to the levels of IL-4, IL-6, and TNF-α, which indicates that the action of FA persisted in the adult offspring, since FA showed a lasting effect on the inflammatory response, which was similar in both the dams and their offspring. In conclusion, the importance of supplementation with FA during pregnancy and lactation should be emphasized, not only for the benefit of the offspring but also for the health of the mother. All this is due to the considerable protective effect of this vitamin against oxidative damage, cognitive impairment, hyperhomocysteinemia, immune function, and also its ability in preventing common processes in post-pregnancy stages, as well as in reducing the risks of neurodevelopmental disorders and enhancing fetal immune development.

Effects of perinatal diet and prenatal stress on the behavioural profile of aged male and female rats

The present work studies whether chronic prenatal stress (PS) influences the long-term sex-dependent neuropsychological status of offspring and the effects of an early dietary intervention in the dam. In addition, dams were fed with either a high-fat sugar diet (HFSD) or methyl donor supplemented diet (MDSD). PS procedure did not affect body weight of the offspring. MDSD induced decreases in body weight both in male and female offspring (1 month) that were still present in aged rats. HFSD induced an increase in body weight both in male and female offspring that did not persist in aged rats. In the Porsolt forced swimming test, only young males showed increases in immobility time that were reversed by MDSD. In old female rats (20 months), PS-induced cognitive impairment in both the novel object recognition test (NORT) and in the Morris water maze that was reversed by MDSD, whereas in old males, cognitive impairments and reversion by MDSD was evident only in the Morris water maze. HFSD induced cognitive impairment in both control and PS old rats, but there was no additive effect of PS and HFSD. It is proposed here that the diversity of symptoms following PS could arise from programming effects in early brain development and that these effects could be modified by dietary intake of the dam.