A paternal methyl donor-rich diet altered cognitive and neural functions in offspring mice

Calling the question: what is mammalian transgenerational epigenetic inheritance?

While transgenerational epigenetic inheritance has been extensively documented in plants, nematodes, and fruit flies, its existence in mammals remains controversial. Several factors have contributed to this debate, including the lack of a clear distinction between intergenerational and transgenerational epigenetic inheritance (TEI), the inconsistency of some studies, the potential confounding effects of in-utero vs. epigenetic factors, and, most importantly, the biological challenge of epigenetic reprogramming. Two waves of epigenetic reprogramming occur: in the primordial germ cells and the developing embryo after fertilization, characterized by global erasure of DNA methylation and remodelling of histone modifications. Consequently, TEI can only occur if specific genetic regions evade this reprogramming and persist through embryonic development. These challenges have revived the long-standing debate about the possibility of inheriting acquired traits, which has been strongly contested since the Lamarckian and Darwinian eras. As a result, coupled with the absence of universally accepted criteria for transgenerational epigenetic studies, a vast body of literature has emerged claiming evidence of TEI. Therefore, the goal of this study is to advocate for establishing fundamental criteria that must be met for a study to qualify as evidence of TEI. We identified five criteria based on the consensus of studies that critically evaluated TEI. To assess whether published original research papers adhere to these criteria, we examined 80 studies that either claimed or were cited as supporting TEI. The findings of this analysis underscore the widespread confusion in this field and highlight the urgent need for a unified scientific consensus on TEI requirements.

The effects of paternal dietary fat versus sugar on offspring body composition and anxiety-related behavior

Increasing evidence suggests that the pre-conception parental environment has long-term consequences for offspring health and disease susceptibility. Though much of the work in this field concentrates on maternal influences, there is growing understanding that fathers also play a significant role in affecting offspring phenotypes. In this study, we investigate effects of altering the proportion of dietary fats and carbohydrates on paternal and offspring body composition and anxiety-related behavior in C57Bl/6-JArc mice. We show that in an isocaloric context, greater dietary fat increased body fat and reduced anxiety-like behavior of studs, whereas increased dietary sucrose had no significant effect. These dietary effects were not reflected in offspring traits, rather, we found sex-specific effects that differed between offspring body composition and behavioral traits. This finding is consistent with past paternal effect studies, where transgenerational effects have been shown to be more prominent in one sex over the other. Here, male offspring of fathers fed high-fat diets were heavier at 10 weeks of age due to increased lean body mass, whereas paternal diet had no significant effect on female offspring body fat or lean mass. In contrast, paternal dietary sugar appeared to have the strongest effects on male offspring behavior, with male offspring of high-sucrose fathers spending less time in the closed arms of the elevated plus maze. Both high-fat and high-sugar paternal diets were found to reduce anxiety-like behavior of female offspring, although this effect was only evident when offspring were fed a control diet. This study provides new understanding of the ways in which diet can shape the behavior of fathers and their offspring and contribute to the development of dietary guidelines to improve obesity and mental health conditions, such as anxiety.

High paternal homocysteine causes ventricular septal defects in mouse offspring

Maternal hyperhomocysteinemia is widely considered as an independent risk of congenital heart disease (CHD). However, whether high paternal homocysteine causes CHD remains unknown. Here, we showed that increased homocysteine levels of male mice caused decreased sperm count, sperm motility defect and ventricular septal defect of the offspring. Moreover, high levels of paternal homocysteine decrease sperm DNMT3A/3B, accompanied with changes in DNA methylation levels in the promoter regions of CHD-related genes. Folic acid supplement could decrease the occurrence of VSD in high homocysteine male mice. This study reveals that increased paternal homocysteine level increases VSD risk in the offspring, indicating that decreasing paternal homocysteine may be an intervening target of CHD.

Association of vitamin B1 intake with geriatric cognitive function: An analysis of the National Health and Nutrition Examination Survey (NHANES) from 2011 to 2014

Background

The association between dietary vitamin B1 intake and cognitive performance in the noninstitutionalized older adult population of the United States remains unclear.

Purpose

This study aimed to investigate the association between vitamin B1 intake and cognitive performance in older adults in the United States.

Methods

Vitamin B1 intake was assessed through two 24-h dietary recalls. Weighted logistic regression was used to evaluate the association between vitamin B1 intake and three cognitive scores (immediate recall test [IRT], animal fluency test [AFT], and digit symbol substitution test [DSST]). Cognitive performance was measured by these three tests, and individuals scoring below the lowest quartile were categorized as cognitive impairment. Sensitivity analysis, including dose-response curves, subgroup analyses, interaction effects, per 1 SD, and quartiles, were performed to ensure the accuracy of the conclusion.

Results

A total of 2896 participants over the age of 60 were included in this study. In the adjusted final model, the association between vitamin B1 intake and low cognitive performance in old age was statistically significant, with the following odds ratios (ORs) and 95% confidence intervals (CIs): IRT, 0.75 (0.57, 0.97), P = 0.018; AFT, 0.68 (0.50, 0.92), P = 0.007; DSST, 0.71 (0.54, 0.92), P = 0.005. Subgroup analyses showed that this association was statistically significant among males, white, low-education, and no memory impairment. The results of the sensitivity analyses confirmed the association between VB1 and cognitive function in old age and the absence of interactions in the final calibrated model.

Conclusion

Dietary vitamin B1 intake is negatively associated with cognitive performance in older adults.

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.

Methyl donor diet attenuates intimal hyperplasia after vascular injury in rats

Environmental factors, particularly dietary habits, play an important role in cardiovascular disease susceptibility and progression through epigenetic modification. Previous studies have shown that hyperplastic vascular intima after endarterectomy is characterized by genome-wide hypomethylation. The purpose of this study was to investigate whether methyl donor diet affects intimal hyperplasia and the possible mechanisms involved. Intimal hyperplasia was induced in SD rats by carotid artery balloon injury. From 8 d before surgery to 28 d after surgery, the animals were fed a normal diet (ND) or a methyl donor diet (MD) supplemented with folic acid, vitamin B12, choline, betaine, and zinc. Carotid artery intimal hyperplasia was observed by histology, the effect of MD on carotid protein expression was analyzed by proteomics, functional clustering, signaling pathway, and upstream-downstream relationship of differentially expressed proteins were analyzed by bioinformatics. Results showed that MD attenuated balloon injury-induced intimal hyperplasia in rat carotid arteries. Proteomic analysis showed that there were many differentially expressed proteins in the common carotid arteries of rats fed with two different diets. The differentially expressed proteins are mainly related to the composition and function of the extracellular matrix (EMC), and changes in the EMC can lead to vascular remodeling by affecting fibrosis and stiffness of the blood vessel wall. Changes in the levels of vasculotropic proteins such as S100A9, ILF3, Serpinh1, Fbln5, LOX, HSPG2, and Fmod may be the reason why MD attenuates intimal hyperplasia. Supplementation with methyl donor nutrients may be a beneficial measure to prevent pathological vascular remodeling after injury.

Characterization of genomic regions escaping epigenetic reprogramming in sheep

The mammalian genome undergoes two global epigenetic reprogramming events during the establishment of primordial germ cells and in the pre-implantation embryo after fertilization. These events involve the erasure and re-establishment of DNA methylation marks. However, imprinted genes and transposable elements (TEs) maintain their DNA methylation signatures to ensure normal embryonic development and genome stability. Despite extensive research in mice and humans, there is limited knowledge regarding environmentally induced epigenetic marks that escape epigenetic reprogramming in other species. Therefore, the objective of this study was to examine the characteristics and locations of genomic regions that evade epigenetic reprogramming in sheep, as well as to explore the biological functions of the genes within these regions. In a previous study, we identified 107 transgenerationally inherited differentially methylated cytosines (DMCs) in the F1 and F2 generations in response to a paternal methionine-supplemented diet. These DMCs were found in TEs, non-repetitive regions, and imprinted and non-imprinted genes. Our findings suggest that genomic regions, rather than TEs and imprinted genes, have the propensity to escape reprogramming and serve as potential candidates for transgenerational epigenetic inheritance. Notably, 34 transgenerational methylated genes influenced by paternal nutrition escaped reprogramming, impacting growth, development, male fertility, cardiac disorders, and neurodevelopment. Intriguingly, among these genes, 21 have been associated with neural development and brain disorders, such as autism, schizophrenia, bipolar disease, and intellectual disability. This suggests a potential genetic overlap between brain and infertility disorders. Overall, our study supports the concept of transgenerational epigenetic inheritance of environmentally induced marks in mammals.

Parental folic acid deficiency delays neurobehavioral development in rat offspring by inhibiting the differentiation of neural stem cells into neurons

Maternal folate status during pregnancy is associated with the neurodevelopment of offspring; however, study results on the association between paternal folate status and offspring neurodevelopment are inconsistent. This study aimed to explore whether parental folic acid deficiency affects the neurobehavioral development of offspring by affecting the differentiation of neural stem cells (NSCs) into neurons. In the present study, the offspring were divided into four groups: parental folic acid deficient group (D-D), maternal folic acid deficient and paternal folic acid normal group (D-N), maternal folic acid normal and paternal folic acid deficient group (N-D), and parental folic acid normal group (N-N). For in vivo study, neurobehavioral indexes, and neuron-specific nuclear protein (NeuN) and glial fibrillary acidic protein (GFAP) expression in the brain hippocampus and cerebral cortex of offspring were measured at different time points. For in vitro study, NSCs were cultured from the hippocampus and striatum, and neuronal and astrocytic differentiation were measured. The results demonstrated that parental folic acid deficiency decreased the brain folate level in offspring, delayed early sensory-motor reflex development, impaired spatial learning and memory ability in adolescence and adulthood, decreased differentiation of NSCs into neurons and increased differentiation of NSCs into astrocytes in vivo and in vitro. These impacts on the neurodevelopment of offspring were most pronounced in D-D group, followed by D-N group and N-D group. In conclusion, parental folic acid deficiency inhibits the neurobehavioral development of offspring, possibly by inhibiting the differentiation of NSCs into neurons.

Parental Folate Deficiency Inhibits Proliferation and Increases Apoptosis of Neural Stem Cells in Rat Offspring: Aggravating Telomere Attrition as a Potential Mechanism

The effect of maternal folate status on the fetal central nervous system (CNS) is well recognized, while evidence is emerging that such an association also exists between fathers and offspring. The biological functions of telomeres and telomerase are also related to neural cell proliferation and apoptosis. The study aimed to investigate the effect of parental folate deficiency on the proliferation and apoptosis of neural stem cells (NSCs) in neonatal offspring and the role of telomeres in this effect. In this study, rats were divided into four groups: maternal folate-deficient and paternal folate-deficient diet (D-D) group; maternal folate-deficient and paternal folate-normal diet (D-N) group; maternal folate-normal and paternal folate-deficient diet (N-D) group; and the maternal folate-normal and paternal folate-normal diet (N-N) group. The offspring were sacrificed at postnatal day 0 (PND0), and NSCs were cultured from the hippocampus and striatum tissues of offspring for future assay. The results revealed that parental folate deficiency decreased folate levels, increased homocysteine (Hcy) levels of the offspring's brain tissue, inhibited proliferation, increased apoptosis, shortened telomere length, and aggravated telomere attrition of offspring NSCs in vivo and in vitro. In vitro experiments further showed that offspring NSCs telomerase activity was inhibited due to parental folate deficiency. In conclusion, parental folate deficiency inhibited the proliferation and increased apoptosis of offspring NSCs, maternal folate deficiency had more adverse effects than paternal, and the mechanisms may involve the telomere attrition of NSCs.

Developmental origins of health and disease: Impact of paternal nutrition and lifestyle

Most epidemiological and experimental studies have focused on maternal influences on offspring's health. The impact of maternal undernutrition, overnutrition, hypoxia, and stress is linked to adverse offspring outcomes across a range of systems including cardiometabolic, respiratory, endocrine, and reproduction among others. During the past decade, it has become evident that paternal environmental factors are also linked to the development of diseases in offspring. In this article, we aim to outline the current understanding of the impact of male health and environmental exposure on offspring development, health, and disease and explore the mechanisms underlying the paternal programming of offspring health. The available evidence suggests that poor paternal pre-conceptional nutrition and lifestyle, and advanced age can increase the risk of negative outcomes in offspring, via both direct (genetic/epigenetic) and indirect (maternal uterine environment) effects. Beginning at preconception, and during utero and the early life after birth, cells acquire an epigenetic memory of the early exposure which can be influential across the entire lifespan and program a child's health. Potentially not only mothers but also fathers should be advised that maintaining a healthy diet and lifestyle is important to improve offspring health as well as the parental health status. However, the evidence is mostly based on animal studies, and well-designed human studies are urgently needed to verify findings from animal data.

Epigenetics and the role of nutraceuticals in health and disease

In the post-genomic era, the data provided by complete genome sequencing could not answer several fundamental questions about the causes of many noninfectious diseases, diagnostic biomarkers, and novel therapeutic approaches. The rapidly expanding understanding of epigenetic mechanisms, as well as widespread acceptance of their hypothesized role in disease induction, facilitated the development of a number of novel diagnostic markers and therapeutic concepts. Epigenetic aberrations are reversible in nature, which enables the treatment of serious incurable diseases. Therefore, the interest in epigenetic modulatory effects has increased over the last decade, so about 60,000 publications discussing the expression of epigenetics could be detected in the PubMed database. Out of these, 58,442 were published alone in the last 10 years, including 17,672 reviews (69 historical articles), 314 clinical trials, 202 case reports, 197 meta-analyses, 156 letters to the editor, 108 randomized controlled trials, 87 observation studies, 40 book chapters, 22 published lectures, and 2 clinical trial protocols. The remaining publications are either miscellaneous or a mixture of the previously mentioned items. According to the species and gender, the publications included 44,589 human studies (17,106 females, 14,509 males, and the gender is not mentioned in the remaining papers) and 30,253 animal studies. In the present work, the role of epigenetic modulations in health and disease and the influencing factors in epigenetics are discussed.

Ca2+- and Voltage-Activated K+ (BK) Channels in the Nervous System: One Gene, a Myriad of Physiological Functions

BK channels are large conductance potassium channels characterized by four pore-forming α subunits, often co-assembled with auxiliary β and γ subunits to regulate Ca2+ sensitivity, voltage dependence and gating properties. BK channels are abundantly expressed throughout the brain and in different compartments within a single neuron, including axons, synaptic terminals, dendritic arbors, and spines. Their activation produces a massive efflux of K+ ions that hyperpolarizes the cellular membrane. Together with their ability to detect changes in intracellular Ca2+ concentration, BK channels control neuronal excitability and synaptic communication through diverse mechanisms. Moreover, increasing evidence indicates that dysfunction of BK channel-mediated effects on neuronal excitability and synaptic function has been implicated in several neurological disorders, including epilepsy, fragile X syndrome, mental retardation, and autism, as well as in motor and cognitive behavior. Here, we discuss current evidence highlighting the physiological importance of this ubiquitous channel in regulating brain function and its role in the pathophysiology of different neurological disorders.

Quercetin modulates the liver metabolic profile in a chronic unpredictable mild stress rat model based on metabolomics technology

Depression is the most prevalent psychiatric disease, and its pathogenesis is still unclear. Currently, studies on the pathogenesis of depression are mainly focused on the brain. The liver can modulate brain function via the liver-brain axis, indicating that the liver plays an important role in the development of depression. This study aims to explore the protective effect of quercetin against chronic unpredictable mild stress (CUMS)-induced metabolic changes and the corresponding mechanisms in the rat liver based on untargeted metabolomics technology. In this study, 96 male rats were divided into six groups: control, different doses of quercetin (10 mg per kg bw or 50 mg per kg bw), CUMS, and CUMS + different doses of quercetin. After 8 weeks of CUMS modeling, the liver samples were collected for metabolomics analysis. A total of 17 altered metabolites were identified, including D-glutamic acid, S-adenosylmethionine, lithocholylglycine, L-homocystine, prostaglandin PGE2, leukotriene E4, cholic acid, 5-methyltetrahydrofolic acid, taurochenodeoxycholic acid, S-adenosylhomocysteine, deoxycholic acid, folic acid, L-methionine, leukotriene C5, estriol-17-glucuronide, PE, and PC, indicating that methionine metabolism, bile acid metabolism, and phosphatidylcholine biosynthesis are the major pathways involved in CUMS-induced hepatic metabolic disorders. Hepatic methylation damage may play a role in the pathophysiology of depression, as evidenced by the first discovery of the abnormality of hepatic methionine metabolism. Abnormal changes in hepatic bile acids may provide stronger evidence for depression pathogenesis involving the microbiota-gut-brain axis, suggesting that the liver is involved in depression development and may be a treatment target. The quercetin treatment alleviated the CUMS-induced liver metabolism disorder, suggesting that quercetin may protect against depression by regulating liver metabolism.

Methyl Donors, Epigenetic Alterations, and Brain Health: Understanding the Connection

Methyl donors such as choline, betaine, folic acid, methionine, and vitamins B6 and B12 are critical players in the one-carbon metabolism and have neuroprotective functions. The one-carbon metabolism comprises a series of interconnected chemical pathways that are important for normal cellular functions. Among these pathways are those of the methionine and folate cycles, which contribute to the formation of S-adenosylmethionine (SAM). SAM is the universal methyl donor of methylation reactions such as histone and DNA methylation, two epigenetic mechanisms that regulate gene expression and play roles in human health and disease. Epigenetic mechanisms have been considered a bridge between the effects of environmental factors, such as nutrition, and phenotype. Studies in human and animal models have indicated the importance of the optimal levels of methyl donors on brain health and behavior across the lifespan. Imbalances in the levels of these micronutrients during critical periods of brain development have been linked to epigenetic alterations in the expression of genes that regulate normal brain function. We present studies that support the link between imbalances in the levels of methyl donors, epigenetic alterations, and stress-related disorders. Appropriate levels of these micronutrients should then be monitored at all stages of development for a healthier brain.

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.

Chronology of natural selection in Oceanian genomes

As human populations left Asia to first settle in Oceania around 50,000 years ago, they entered a territory ecologically separated from the Old World for millions of years. We analyzed genomic data of 239 modern Oceanian individuals to detect and date signals of selection specific to this region. Combining both relative and absolute dating approaches, we identified a strong selection pattern between 52,000 and 54,000 years ago in the genomes of descendants of the first settlers of Sahul. This strikingly corresponds to the dates of initial settlement as inferred from archaeological evidence. Loci under selection during this period, some showing enrichment in Denisovan ancestry, overlap genes involved in the immune response and diet, especially based on plants. Pathogens and natural resources, especially from endemic plants, therefore appear to have acted as strong selective pressures on the genomes of the first settlers of Sahul.

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239 human genomes from both sides of the Wallacean ecogeographical barriers

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Signals of selection are dated between -54,000 to -52,000 in modern Oceanian genomes

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Genes related to immunity and diet were under strong selection

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Denisovan introgressions participated to the genetic adaptations present in Oceanians

Programming of Embryonic Development

Assisted reproductive techniques (ART) and parental nutritional status have profound effects on embryonic/fetal and placental development, which are probably mediated via "programming" of gene expression, as reflected by changes in their epigenetic landscape. Such epigenetic changes may underlie programming of growth, development, and function of fetal organs later in pregnancy and the offspring postnatally, and potentially lead to long-term changes in organ structure and function in the offspring as adults. This latter concept has been termed developmental origins of health and disease (DOHaD), or simply developmental programming, which has emerged as a major health issue in animals and humans because it is associated with an increased risk of non-communicable diseases in the offspring, including metabolic, behavioral, and reproductive dysfunction. In this review, we will briefly introduce the concept of developmental programming and its relationship to epigenetics. We will then discuss evidence that ART and periconceptual maternal and paternal nutrition may lead to epigenetic alterations very early in pregnancy, and how each pregnancy experiences developmental programming based on signals received by and from the dam. Lastly, we will discuss current research on strategies designed to overcome or minimize the negative consequences or, conversely, to maximize the positive aspects of developmental programming.

Early Life Nutrition and Mental Health: The Role of DNA Methylation

Does the quality of our diet during early life impact our long-term mental health? Accumulating evidence suggests that nutrition interacts with our genes and that there is a strong association between the quality of diet and mental health throughout life. Environmental influences such as maternal diet during pregnancy or offspring diet have been shown to cause epigenetic changes during critical periods of development, such as chemical modifications of DNA or histones by methylation for the regulation of gene expression. One-carbon metabolism, which consists of the folate and methionine cycles, is influenced by the diet and generates S-Adenosylmethinoine (SAM), the main methyl donor for methylation reactions such as DNA and histone methylation. This review provides current knowledge on how the levels of one-carbon metabolism associated micronutrients such as choline, betaine, folate, methionine and B vitamins that play a role in brain function can impact our well-being and mental health across the lifespan. Micronutrients that act as methyl donors for SAM formation could affect global or gene methylation, altering gene expression and phenotype. Strategies should then be adopted to better understand how these nutrients work and their impact at different stages of development to provide individualized dietary recommendations for better mental health outcomes.

Consequences of Paternal Nutrition on Offspring Health and Disease

It is well established that the maternal diet during the periconceptional period affects the progeny’s health. A growing body of evidence suggests that the paternal diet also influences disease onset in offspring. For many years, sperm was considered only to contribute half of the progeny’s genome. It now appears that it also plays a crucial role in health and disease in offspring’s adult life. The nutritional status and environmental exposure of fathers during their childhood and/or the periconceptional period have significant transgenerational consequences. This review aims to describe the effects of various human and rodent paternal feeding patterns on progeny’s metabolism and health, including fasting or intermittent fasting, low-protein and folic acid deficient food, and overnutrition in high-fat and high-sugar diets. The impact on pregnancy outcome, metabolic pathways, and chronic disease onset will be described. The biological and epigenetic mechanisms underlying the transmission from fathers to their progeny will be discussed. All these data provide evidence of the impact of paternal nutrition on progeny health which could lead to preventive diet recommendations for future fathers.

Of 'junk food' and 'brain food': how parental diet influences offspring neurobiology and behaviour

Unhealthy lifestyles and mental health problems are increasingly prevalent globally. Not only are 'junk food'-induced overweight and obesity risk factors for the development of brain disorders but they are also associated intergenerationally with ill health. Here, we reflect on the current knowledge of how maternal and paternal diet influences offspring brain development and behaviour, potentially predisposing children to mental health problems. Mounting evidence indicates diet-induced maternal and paternal programming of infant metabolism and neurobehavioural function, with potential downstream effects on mental health and resilience. Beyond the central nervous system (CNS), the microbiota-gut-brain axis has emerged as an important mediator of host physiology. We discuss how intergenerational seeding of the gut microbiome via parental lineage can influence offspring gut health and neurobiology.

Paternal exposure to excessive methionine altered behavior and neurochemical activities in zebrafish offspring

An increase in plasma L-methionine (Met) levels, even if transitory, can cause important toxicological alterations in the affected individuals. Met is essential in the regulation of epigenetic mechanisms and its influence on the subsequent generation has been investigated. However, few studies have explored the influence of a temporary increase in Met levels in parents on their offspring. This study evaluated the behavioral and neurochemical effects of parental exposure to high Met concentration (3 mM) in zebrafish offspring. Adult zebrafish were exposed to Met for 7 days, maintained for additional 7 days in tanks that contained only water, and then used for breeding. The offspring obtained from these fish (F1) were tested in this study. During the early stages of offspring development, morphology, heart rate, survival, locomotion, and anxiety-like behavior were assessed. When these animals reached the adult stage, locomotion, anxiety, aggression, social interaction, memory, oxidative stress, and levels of amino acids and neurotransmitters were analyzed. F1 larvae Met group presented an increase in the distance and mean speed when compared to the control group. F1 adult Met group showed decreased anxiety-like behavior and locomotion. An increase in reactive oxygen species was also observed in the F1 adult Met group whereas lipid peroxidation and antioxidant enzymes did not change when compared to the control group. Dopamine, serotonin, glutamate, and glutathione levels were increased in the F1 adult Met group. Taken together, our data show that even a transient increase in Met in parents can cause behavioral and neurochemical changes in the offspring, promoting transgenerational effects.

Low protein diet and methyl-donor supplements modify testicular physiology in mice

The link between male diet and sperm quality has received significant investigation. However, the impact diet and dietary supplements have on the testicular environment has been examined to a lesser extent. Here, we establish the impact of a sub-optimal low protein diet (LPD) on testicular morphology, apoptosis and serum fatty acid profiles. Furthermore, we define whether supplementing a LPD with specific methyl donors abrogates any detrimental effects of the LPD. Male C57BL6 mice were fed either a control normal protein diet (NPD; 18% protein; n = 8), an isocaloric LPD (LPD; 9% protein; n = 8) or an LPD supplemented with methyl donors (MD-LPD; choline chloride, betaine, methionine, folic acid, vitamin B12; n = 8) for a minimum of 7 weeks. Analysis of male serum fatty acid profiles by gas chromatography revealed elevated levels of saturated fatty acids and lower levels of mono- and polyunsaturated fatty acids in MD-LPD males when compared to NPD and/or LPD males. Testes of LPD males displayed larger seminiferous tubule cross section area when compared to NPD and MD-LPD males, while MD-LPD tubules displayed a larger luminal area. Furthermore, TUNNEL staining revealed LPD males possessed a reduced number of tubules positive for apoptosis, while gene expression analysis showed MD-LPD testes displayed decreased expression of the pro-apoptotic genes Bax, Csap1 and Fas when compared to NPD males. Finally, testes from MD-LPD males displayed a reduced telomere length but increased telomerase activity. These data reveal the significance of sub-optimal nutrition for paternal metabolic and reproductive physiology.

Dietary nutrition for neurological disease therapy: Current status and future directions

Adequate food intake and relative abundance of dietary nutrients have undisputed effects on the brain function. There is now substantial evidence that dietary nutrition aids in the prevention and remediation of neurologic symptoms in diverse pathological conditions. The newly described influences of dietary factors on the alterations of mitochondrial dysfunction, epigenetic modification and neuroinflammation are important mechanisms that are responsible for the action of nutrients on the brain health. In this review, we discuss the state of evidence supporting that distinct dietary interventions including dietary supplement and dietary restriction have the ability to tackle neurological disorders using Alzheimer's disease, Parkinson's disease, stroke, epilepsy, traumatic brain injury, amyotrophic lateral sclerosis, Huntington's disease and multiple sclerosis as examples. Additionally, it is also highlighting that diverse potential mechanisms such as metabolic control, epigenetic modification, neuroinflammation and gut-brain axis are of utmost importance for nutrient supply to the risk of neurologic condition and therapeutic response. Finally, we also highlight the novel concept that dietary nutrient intervention reshapes metabolism-epigenetics-immunity cycle to remediate brain dysfunction. Targeting metabolism-epigenetics-immunity network will delineate a new blueprint for combating neurological weaknesses.

Excessive rumen-protected choline in the daily diet compromises sperm quality of male dairy goats as a result of aberrant DNA methylation modification

Context Choline is added to the diet of ruminants to improve animal growth, development and reproduction; however, little information is available regarding effects of dietary choline supplementation, in the form of rumen-protected choline (RPC), on fertility of male ruminants. Excess RPC in the diet might damage ram fertility through abnormal alteration of methylation patterns at the imprinting control region (ICR) of imprinted genes H19/IGF2. Aims The present study evaluated the influence of different levels of RPC supplementation on the sperm quality of male Saanen dairy goats. Methods Different proportions of RPC (0%, 0.5%, 1.0% and 2.0% of daily concentrate feed) were added to the diet of Saanen bucks. Sperm quality parameters, subsequent in vitro embryo development potential, and kidding rates post artificial insemination were examined. In addition, differences in methylation status of the global DNA, and at 20 CpG sites in the ICR of imprinted genes H19/IGF2, were compared. Key results Supplementation of the daily diet with 0.5% RPC significantly improved sperm quality, and increased subsequent embryo development and kidding rates. However, the two higher RPC-supplemented groups showed significantly reduced kidding rate. Moreover, methylation levels of both the ICR of H19/IGF2 and the global DNA increased significantly with increasing supplemental RPC, and the expression of IGF2 was significantly inhibited in sperm samples from the 1.0% and 2.0% RPC groups, whereas H19, which should had been silenced, showed high expression. Conclusions Adding excessive RPC (≥1%) to the daily diet of male goats might disturb the process of spermatogenesis and is associated with abnormal methylation modification caused by aberrant expression of DNMT1, DNMT3a and DNMT3b in sperm. Implications This study determines the safe amount of choline to add to the diet during the breeding of male dairy goats. This provides a reference for improving the breeding efficiency and saving the breeding cost of dairy goats.

Mapping the past, present and future research landscape of paternal effects

BACKGROUND

Although in all sexually reproducing organisms an individual has a mother and a father, non-genetic inheritance has been predominantly studied in mothers. Paternal effects have been far less frequently studied, until recently. In the last 5 years, research on environmentally induced paternal effects has grown rapidly in the number of publications and diversity of topics. Here, we provide an overview of this field using synthesis of evidence (systematic map) and influence (bibliometric analyses).

RESULTS

We find that motivations for studies into paternal effects are diverse. For example, from the ecological and evolutionary perspective, paternal effects are of interest as facilitators of response to environmental change and mediators of extended heredity. Medical researchers track how paternal pre-fertilization exposures to factors, such as diet or trauma, influence offspring health. Toxicologists look at the effects of toxins. We compare how these three research guilds design experiments in relation to objects of their studies: fathers, mothers and offspring. We highlight examples of research gaps, which, in turn, lead to future avenues of research.

CONCLUSIONS

The literature on paternal effects is large and disparate. Our study helps in fostering connections between areas of knowledge that develop in parallel, but which could benefit from the lateral transfer of concepts and methods.

Defining the male contribution to embryo quality and offspring health in assisted reproduction in farm animals

Assisted reproductive technologies such as artificial insemination have delivered significant benefits for farm animal reproduction. However, as with humans, assisted reproduction in livestock requires the manipulation of the gametes and preimplantation embryo. The significance of this ‘periconception’ period is that it represents the transition from parental genome regulation to that of the newly formed embryo. Environmental perturbations during these early developmental stages can result in persistent changes in embryonic gene expression, fetal organ development and ultimately the long-term health of the offspring. While associations between maternal health and offspring wellbeing are well-defined, the significance of paternal health for the quality of his semen and the post-conception development of his offspring have largely been overlooked. Human and animal model studies have identified sperm epigenetic status (DNA methylation levels, histone modifications and RNA profiles) and seminal plasma-mediated maternal uterine immunological, inflammatory and vascular responses as the two central mechanisms capable of linking paternal health and post-fertilisation development. However, there is a significant knowledge gap about the father’s contribution to the long-term health of his offspring, especially with regard to farm animals. Such insights are essential to ensure the safety of widely used assisted reproductive practices and to gain better understanding of the role of paternal health for the well-being of his offspring. In this article, we will outline the impact of male health on semen quality (both sperm and seminal plasma), reproductive fitness and post-fertilisation offspring development and explore the mechanisms underlying the paternal programming of offspring health in farm animals.

Metabolomic and transcriptomic signatures of prenatal excessive methionine support nature rather than nurture in schizophrenia pathogenesis

The imbalance of prenatal micronutrients may perturb one-carbon (C1) metabolism and increase the risk for neuropsychiatric disorders. Prenatal excessive methionine (MET) produces in mice behavioral phenotypes reminiscent of human schizophrenia. Whether in-utero programming or early life caregiving mediate these effects is, however, unknown. Here, we show that the behavioral deficits of MET are independent of the early life mother-infant interaction. We also show that MET produces in early life profound changes in the brain C1 pathway components as well as glutamate transmission, mitochondrial function, and lipid metabolism. Bioinformatics analysis integrating metabolomics and transcriptomic data reveal dysregulations of glutamate transmission and lipid metabolism, and identify perturbed pathways of methylation and redox reactions. Our transcriptomics Linkage analysis of MET mice and schizophrenia subjects reveals master genes involved in inflammation and myelination. Finally, we identify potential metabolites as early biomarkers for neurodevelopmental defects and suggest therapeutic targets for schizophrenia.

Chen, Alhassen et al. show that schizophrenia-like behavioral deficits induced by excessive prenatal methionine administration are due to in-uterus aberrations rather than through early life mother-infant interaction in mice. This study identifies the brain metabolites and transcriptomic signatures, which potentially serve as early biomarkers for schizophrenia-like behaviors.

Interplay between Metabolism, Nutrition and Epigenetics in Shaping Brain DNA Methylation, Neural Function and Behavior

Gene expression in the brain is dramatically regulated by a variety of stimuli. While the role of neural activity has been extensively studied, less is known about the effects of metabolism and nutrition on transcriptional control mechanisms in the brain. Extracellular signals are integrated at the chromatin level through dynamic modifications of epigenetic marks, which in turn fine-tune gene transcription. In the last twenty years, it has become clear that epigenetics plays a crucial role in modulating central nervous system functions and finally behavior. Here, we will focus on the effect of metabolic signals in shaping brain DNA methylation, both during development and adulthood. We will provide an overview of maternal nutrition effects on brain methylation and behavior in offspring. In addition, the impact of different diet challenges on cytosine methylation dynamics in the adult brain will be discussed. Finally, the possible role played by the metabolic status in modulating DNA hydroxymethylation, which is particularly abundant in neural tissue, will be considered.

The Copenhagen Primary Care Laboratory Pregnancy (CopPreg) database

PURPOSE

The Copenhagen Primary Care Laboratory Pregnancy (CopPreg) database was established based on data from The Danish Medical Birth Register and the Copenhagen Primary Care Laboratory (CopLab) database. The aim was to provide a biomedical and epidemiological data resource for research in early disease programming (eg, parental clinical biomarker levels and pregnancy/ birth outcomes or long-term health in the offspring).

PARTICIPANTS

The cohort consisted in total of 203 608 women (with 340 891 pregnancies) who gave birth to 348 248 children and with 200 590 related fathers. In this paper, we focused on women and fathers who had clinical test requisitions prior to and during pregnancy, and on all children. Thus, the cohort in focus consisted of 203 054 pregnancies with requisitions on 147 045 pregnant women, 39 815 fathers with requisitions during periconception and 65 315 children with requisitions.

FINDINGS TO DATE

In addition to information on pregnancy and birth health status and general socio-demographic data, over 2.2 million clinically relevant test results were available for pregnancies with requisitions, over 1.5 million for children and over 600 000 test results were available for the fathers with requisitions during periconception. These were ordered by general practitioners in the primary care setting only and included general blood tests, nutritional biomarkers (macronutrients and micronutrients) and hormone tests. Information on tests related to infections, allergies, heart and lung function and sperm analyses (fathers) were also available.

FUTURE PLANS

The CopPreg database provides ready to use and valid data from already collected, objectively measured and analysed clinical tests. With several research projects planned, we further invite national and international researchers to use this vast data resource. In a coming paper, we will explore and discuss the indication bias in our cohort.

Prenatal S-Adenosine Methionine (SAMe) Induces Changes in Gene Expression in the Brain of Newborn Mice That Are Prevented by Co-Administration of Valproic Acid (VPA)

In previous studies, we produced changes in gene expression in the brain of mice by early postnatal administration of valproic acid (VPA), with distinct differences between genders. The addition of S-adenosine methionine (SAMe) normalized the expression of most genes in both genders, while SAMe alone induced no changes. We treated pregnant dams with a single injection of VPA on day 12.5 of gestation, or with SAMe during gestational days 12–14, or by a combination of VPA and SAMe. In the frontal half of the brain, we studied the expression of 770 genes of the pathways involved in neurophysiology and neuropathology using the NanoString nCounter method. SAMe, but not VPA, induced statistically significant changes in the expression of many genes, with differences between genders. The expression of 112 genes was changed in both sexes, and another 170 genes were changed only in females and 31 only in males. About 30% of the genes were changed by more than 50%. One of the most important pathways changed by SAMe in both sexes was the VEGF (vascular endothelial growth factor) pathway. Pretreatment with VPA prevented almost all the changes in gene expression induced by SAMe. We conclude that large doses of SAMe, if administered prenatally, may induce significant epigenetic changes in the offspring. Hence, SAMe and possibly other methyl donors may be epigenetic teratogens.

Maternal Folic Acid Supplementation Mediates Offspring Health via DNA Methylation

The clinical significance of periconceptional folic acid supplementation (FAS) in the prevention of neonatal neural tube defects (NTDs) has been recognized for decades. Epidemiological data and experimental findings have consistently been indicating an association between folate deficiency in the first trimester of pregnancy and poor fetal development as well as offspring health (i.e., NTDs, isolated orofacial clefts, neurodevelopmental disorders). Moreover, compelling evidence has suggested adverse effects of folate overload during perinatal period on offspring health (i.e., immune diseases, autism, lipid disorders). In addition to several single-nucleotide polymorphisms (SNPs) in genes related to folate one-carbon metabolism (FOCM), folate concentrations in maternal serum/plasma/red blood cells must be considered when counseling FAS. Epigenetic information encoded by 5-methylcytosines (5mC) plays a critical role in fetal development and offspring health. S-adenosylmethionine (SAM), a methyl donor for 5mC, could be derived from FOCM. As such, folic acid plays a double-edged sword role in offspring health via mediating DNA methylation. However, the underlying epigenetic mechanism is still largely unclear. In this review, we summarized the link across DNA methylation, maternal FAS, and offspring health to provide more evidence for clinical guidance in terms of precise FAS dosage and time point. Future studies are, therefore, required to set up the reference intervals of folate concentrations at different trimesters of pregnancy for different populations and to clarify the epigenetic mechanism for specific offspring diseases.

A toolbox for the longitudinal assessment of healthspan in aging mice

The number of people aged over 65 is expected to double in the next 30 years. For many, living longer will mean spending more years with the burdens of chronic diseases such as Alzheimer's disease, cardiovascular disease, and diabetes. Although researchers have made rapid progress in developing geroprotective interventions that target mechanisms of aging and delay or prevent the onset of multiple concurrent age-related diseases, a lack of standardized techniques to assess healthspan in preclinical murine studies has resulted in reduced reproducibility and slow progress. To overcome this, major centers in Europe and the United States skilled in healthspan analysis came together to agree on a toolbox of techniques that can be used to consistently assess the healthspan of mice. Here, we describe the agreed toolbox, which contains protocols for echocardiography, novel object recognition, grip strength, rotarod, glucose tolerance test (GTT) and insulin tolerance test (ITT), body composition, and energy expenditure. The protocols can be performed longitudinally in the same mouse over a period of 4-6 weeks to test how candidate geroprotectors affect cardiac, cognitive, neuromuscular, and metabolic health.

Editing DNA Methylation in Mammalian Embryos

DNA methylation in mammals is essential for numerous biological functions, such as ensuring chromosomal stability, genomic imprinting, and X-chromosome inactivation through transcriptional regulation. Gene knockout of DNA methyltransferases and demethylation enzymes has made significant contributions to analyzing the functions of DNA methylation in development. By applying epigenome editing, it is now possible to manipulate DNA methylation in specific genomic regions and to understand the functions of these modifications. In this review, we first describe recent DNA methylation editing technology. We then focused on changes in DNA methylation status during mammalian gametogenesis and preimplantation development, and have discussed the implications of applying this technology to early embryos.

Periconceptional environment and the developmental origins of disease

The concept emerging from Professor David Barker’s seminal research on the developmental origins of later-life disease has progressed in many directions since it was first published. One critical question being when during gestation might environment alter the developmental programme with such enduring consequences. Here, we review the growing consensus from clinical and animal research that the period around conception, embracing gamete maturation and early embryogenesis might be the most vulnerable period. We focus on four types of environmental exposure shown to modify periconceptional reproduction and offspring development and health: maternal overnutrition and obesity; maternal undernutrition; paternal diet and health; and assisted reproductive technology. These conditions may act through diverse epigenetic, cellular and physiological mechanisms to alter gene expression and cellular signalling and function in the conceptus affecting offspring growth and metabolism leading to increased risk for cardiometabolic and neurological disease in later life.

An appraisal of folates as key factors in cognition and ageing-related diseases

Folic acid (FA) is often consumed as a food supplement and can be found in fortified staple foods in various western countries. Even though FA supplementation during pregnancy is known to prevent severe congenital anomalies in the developing child (e.g., neural tube defects), much less is known about its influence on cognition and neurological functioning. In this review, we address the advances in this field and situate how folate intake during pregnancy, postnatal life, adulthood and in the elderly affects cognition. In addition, an association between folate status and ageing, dementia and other neurodegenerative disorders such as Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis is discussed. While its role in the incidence and severity of these diseases is becoming apparent, the underlying action of folates and related metabolites remains elusive. Finally, the potential of FA as a nutraceutical has been proposed, although the efficacy will highly depend on the interplay with other micronutrients, the disease stage and the duration of supplementation. Hence, the lack of consistent data urges for more animal studies and (pre)clinical trials in humans to ascertain a potential beneficial role for folates in the treatment or amelioration of cognitive decline and ageing-related disorders.

Overexpression of Kcnmb2 in Dorsal CA1 of Offspring Mice Rescues Hippocampal Dysfunction Caused by a Methyl Donor-Rich Paternal Diet

BK channels are known regulators of neuronal excitability, synaptic plasticity, and memory. Our previous study showed that a paternal methyl donor-rich diet reduced the expression of Kcnmb2, which encodes BK channel subunit beta 2, and caused memory deficits in offspring mice. To explore the underlying cellular mechanisms, we investigated the intrinsic and synaptic properties of CA1 pyramidal neurons of the F1 offspring mice whose fathers were fed with either a methyl donor-rich diet (MD) or regular control diet (CD) for 6 weeks before mating. Whole-cell patch-clamp recordings of CA1 pyramidal neurons revealed a decrease in intrinsic excitability and reduced frequency of inhibitory post-synaptic currents in MD F1 mice compared to the CD F1 controls. AAV-based overexpression of Kcnmb2 in dorsal CA1 ameliorated changes in neuronal excitability, synaptic transmission, and plasticity in MD F1 mice. Our findings thus indicate that a transient paternal exposure to a methyl donor-rich diet prior to mating alters Kcnmb2-sensitive hippocampal functions in offspring animals.

Establishing normal metabolism and differentiation in hepatocellular carcinoma cells by culturing in adult human serum

Tissue culture medium routinely contains fetal bovine serum (FBS). Here we show that culturing human hepatoma cells in their native, adult serum (human serum, HS) results in the restoration of key morphological and metabolic features of normal liver cells. When moved to HS, these cells show differential transcription of 22–32% of the genes, stop proliferating, and assume a hepatocyte-like morphology. Metabolic analysis shows that the Warburg-like metabolic profile, typical for FBS-cultured cells, is replaced by a diverse metabolic profile consistent with in vivo hepatocytes, including the formation of large lipid and glycogen stores, increased glycogenesis, increased beta-oxidation and ketogenesis, and decreased glycolysis. Finally, organ-specific functions are restored, including xenobiotics degradation and secretion of bile, VLDL and albumin. Thus, organ-specific functions are not necessarily lost in cell cultures, but might be merely suppressed in FBS. The effect of serum is often overseen in cell culture and we provide a detailed study in the changes that occur and provide insight in some of the serum components that may play a role in the establishment of the differentiated phenotype.

A paternal methyl donor depleted diet leads to increased anxiety- and depression-like behavior in adult rat offspring

Epigenetic mechanisms such as DNA methylation elicit lasting changes in gene expression and likely mediate gene-environment interactions that shape brain development, behavior, and emotional health. Myriad environmental factors influence DNA methylation, including methyl donor content in the paternal diet, could influence methylation in offspring via changes in the paternal germ line. The present study examines the effects of paternal methyl donor dietary deficiency on offspring's emotional behaviors, including anxiety, social interaction, and depression-like behavior. We previously found that rats bred to display high levels of anxiety- and depression-like behavior exhibit diminished DNA methylation in the amygdala. We also observed that depleting dietary methyl donor content exacerbated the rats' already high levels of anxiety- and depression-like behavior. Here we sought to determine whether paternal dietary methyl donor depletion elicits intergenerational effects on first generation (F1) offspring's behavior (potentially triggering a similar increase in anxiety- and/or depression-like behavior). Thus, adult male rats prone to high anxiety/depression-like behavior, were fed either a methyl donor depleted (DEP) or control (CON) diet for 5 weeks prior to mating. They were paired with females and resultant F1 male offspring were subjected to a behavioral test battery in adulthood. F1-DEP offspring showed a similar behavioral profile to the F0 males, including greater depression-like behavior in the forced swim test (FST) and increased anxiety-like behavior in the open field test (OFT). Future work will interrogate molecular changes in the brains of F1 offspring that mediate these intergenerational effects of paternal methyl donor dietary content on offspring emotional behavior.

Epigenetic alterations in longevity regulators, reduced life span, and exacerbated aging-related pathology in old father offspring mice

Advanced age is not only a major risk factor for a range of disorders within an aging individual but may also enhance susceptibility for disease in the next generation. In humans, advanced paternal age has been associated with increased risk for a number of diseases. Experiments in rodent models have provided initial evidence that paternal age can influence behavioral traits in offspring animals, but the overall scope and extent of paternal age effects on health and disease across the life span remain underexplored. Here, we report that old father offspring mice showed a reduced life span and an exacerbated development of aging traits compared with young father offspring mice. Genome-wide epigenetic analyses of sperm from aging males and old father offspring tissue identified differentially methylated promoters, enriched for genes involved in the regulation of evolutionarily conserved longevity pathways. Gene expression analyses, biochemical experiments, and functional studies revealed evidence for an overactive mTORC1 signaling pathway in old father offspring mice. Pharmacological mTOR inhibition during the course of normal aging ameliorated many of the aging traits that were exacerbated in old father offspring mice. These findings raise the possibility that inherited alterations in longevity pathways contribute to intergenerational effects of aging in old father offspring mice.

Supplement of Betaine into Embryo Culture Medium Can Rescue Injury Effect of Ethanol on Mouse Embryo Development

Mammal embryos can be impaired by mother’s excessive ethanol uptake, which induces a higher level of reactive oxygen species (ROS) and interferes in one carbon unit metabolism. Here, our analysis by in vitro culture system reveals immediate effect of ethanol in medium on mouse embryo development presents concentration dependent. A preimplantation embryo culture using medium contained 1% ethanol could impact greatly early embryos development, and harmful effect of ethanol on preimplantation embryos would last during the whole development period including of reducing ratio of blastocyst formation and implantation, and deteriorating postimplantation development. Supplement of 50 μg/ml betaine into culture medium can effectively reduce the level of ROS caused by ethanol in embryo cells and rescue embryo development at each stage damaged by ethanol, but supplement of glycine can’t rescue embryo development as does betaine. Results of 5-methylcytosine immunodetection indicate that supplement of betaine into medium can reduce the rising global level of genome DNA methylation in blastocyst cells caused by 1% ethanol, but glycine can’t play the same impact. The current findings demonstrate that betaine can effectively rescue development of embryos harmed by ethanol, and possibly by restoring global level of genome DNA methylation in blastocysts.

High-dose maternal folic acid supplementation before conception impairs reversal learning in offspring mice

Maternal folic acid (FA) supplementation prior to and during gestation is recommended for the prevention of neural tube closure defects in the developing embryo. Prior studies, however, suggested that excessive FA supplementation during gestation can be associated with toxic effects on the developing organism. Here, we address whether maternal dietary folic acid supplementation at 40 mg/kg chow (FD), restricted to a period prior to conception, affects neurobehavioural development in the offspring generation. Detailed behavioural analyses showed reversal learning impairments in the Morris water maze in offspring derived from dams exposed to FD prior to conceiving. Furthermore, offspring of FD dams showed minor and transient gene expression differences relative to controls. Our data suggest that temporary exposure of female germ cells to FD is sufficient to cause impaired cognitive flexibility in the subsequent generation.