Folate-mediated one-carbon metabolism and its effect on female fertility and pregnancy viability

The Role of One-Carbon Metabolism and Methyl Donors in Medically Assisted Reproduction: A Narrative Review of the Literature

One-carbon (1-C) metabolic deficiency impairs homeostasis, driving disease development, including infertility. It is of importance to summarize the current evidence regarding the clinical utility of 1-C metabolism-related biomolecules and methyl donors, namely, folate, betaine, choline, vitamin B12, homocysteine (Hcy), and zinc, as potential biomarkers, dietary supplements, and culture media supplements in the context of medically assisted reproduction (MAR). A narrative review of the literature was conducted in the PubMed/Medline database. Diet, ageing, and the endocrine milieu of individuals affect both 1-C metabolism and fertility status. In vitro fertilization (IVF) techniques, and culture conditions in particular, have a direct impact on 1-C metabolic activity in gametes and embryos. Critical analysis indicated that zinc supplementation in cryopreservation media may be a promising approach to reducing oxidative damage, while female serum homocysteine levels may be employed as a possible biomarker for predicting IVF outcomes. Nonetheless, the level of evidence is low, and future studies are needed to verify these data. One-carbon metabolism-related processes, including redox defense and epigenetic regulation, may be compromised in IVF-derived embryos. The study of 1-C metabolism may lead the way towards improving MAR efficiency and safety and ensuring the lifelong health of MAR infants.

Effect of in ovo feeding of folic acid on Disabled-1 and gga-miR-182-5p expression in the cerebral cortex of chick embryo

Folate (vitamin B9) has been shown to reduce the prevalence of neural tube defects (NTDs). Many genes comprising Disabled-1 (DAB1) and miRNAs have been shown to play important role in normal brain development. Reelin-signalling has been shown to play key role in regulating of neuronal migration during brain development. The aim of this study was to evaluate the effects of in ovo administration of folic acid (FA) on DAB1 and gga-miR-182-5p expression in the cerebral cortex of chick embryo. A total number of 30 hatching eggs were used in this study. The number of 10 eggs were injected into the yolk sac with FA (150 µg/egg), 10 eggs by normal saline (sham group) on embryonic day 11 and 10 eggs were left without injection as control. Then the cerebral cortices were collected on E19 and the expression of DAB1 and gga-miR-182-5p was studied by Real-Time PCR. The results showed that DAB1 expression in the cerebral cortex of FA-treated, sham and control were 2.51 ± 0.13, 1.01 ± 0.04 and 1.03 ± 0.04 fold changes, respectively, and this amount for gga-miR-182-5p were 0.54 ± 0.03, 1.09 ± 0.07 and 1.00 ± 0.06-fold change respectively. Statistical analysis showed that there is a significant increase in DAB1 and a decrease in gga-miR-182-5p expression in FA injected cerebral cortex as compared either with either SHAM or control (p < 0.0001). But, no significant change in DAB1 and gga-miR-182-5p expression was observed between sham and the control group (p = 0.99 and p = 0.57 respectively). It is concluded that in ovo feeding of FA increases DAB1 and decreases gga-miR-182-5p expression in the developing chick cerebral cortex.

Food, nutrition, and fertility: from soil to fork

Food and nutrition-related factors, including foods and nutrients consumed, dietary patterns, use of dietary supplements, adiposity, and exposure to food-related environmental contaminants, have the potential to impact semen quality and male and female fertility; obstetric, fetal, and birth outcomes; and the health of future generations, but gaps in evidence remain. On 9 November 2022, Tufts University's Friedman School of Nutrition Science and Policy and the school's Food and Nutrition Innovation Institute hosted a 1-d meeting to explore the evidence and evidence gaps regarding the relationships between food, nutrition, and fertility. Topics addressed included male fertility, female fertility and gestation, and intergenerational effects. This meeting report summarizes the presentations and deliberations from the meeting. Regarding male fertility, a positive association exists with a healthy dietary pattern, with high-quality evidence for semen quality and lower quality evidence for clinical outcomes. Folic acid and zinc supplementation have been found to not impact male fertility. In females, body weight status and other nutrition-related factors are linked to nearly half of all ovulation disorders, a leading cause of female infertility. Females with obesity have worse fertility treatment, pregnancy-related, and birth outcomes. Environmental contaminants found in food, water, or its packaging, including lead, perfluorinated alkyl substances, phthalates, and phenols, adversely impact female reproductive outcomes. Epigenetic research has found that maternal and paternal dietary-related factors can impact outcomes for future generations. Priority evidence gaps identified by meeting participants relate to the effects of nutrition and dietary patterns on fertility, gaps in communication regarding fertility optimization through changes in nutritional and environmental exposures, and interventions impacting germ cell mechanisms through dietary effects. Participants developed research proposals to address the priority evidence gaps. The workshop findings serve as a foundation for future prioritization of scientific research to address evidence gaps related to food, nutrition, and fertility.

Folate - a scoping review for Nordic Nutrition Recommendations 2023

Folate is an essential micronutrient for normal development and metabolic function, and folate deficiency is associated with an increased risk of cancer, cardiovascular disease, mental dysfuntion and negative pregnancy outcomes. When estimating folate requirements, one must consider different bioavailability and functionality between synthetic folic acid and dietary folate, together with increased needs of folate in women of fertile age, pregnant and lactating women, preterm and small for gestational age weight infants and individuals who are homozygote for the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene polymorphism. In order to achieve an adequate metabolic status based on the metabolic marker total homocysteine, and not merely the absence of clinical signs of folate deficiency, the recommended intake of folate differs according to age, pregnancy and lactation. According to the World Health Organization, a decision limit for folate deficiency in adults is serum folate level below 10 nmol/L, and in women of fertile age a red blood cell folate level below 906 nmol/L in order to prevent neural tube defects. Qualified systematic reviews along with identified relevant literature have been used for this scoping review prepared for the Nordic Nutrition Recommendations 2023.

Folate-producing bifidobacteria: metabolism, genetics, and relevance

Folate (the general term for all bioactive forms of vitamin B9) plays a crucial role in the evolutionary highly conserved one-carbon (1C) metabolism, a network including central reactions such as DNA and protein synthesis and methylation of macromolecules. Folate delivers 1C units, such as methyl and formyl, between reactants. Plants, algae, fungi, and many bacteria can naturally produce folate, whereas animals, including humans, must obtain folate from external sources. For humans, folate deficiency is, however, a widespread problem. Bifidobacteria constitute an important component of human and many animal microbiomes, providing various health advantages to the host, such as producing folate. This review focuses on bifidobacteria and folate metabolism and the current knowledge of the distribution of genes needed for complete folate biosynthesis across different bifidobacterial species. Biotechnologies based on folate-trophic probiotics aim to create fermented products enriched with folate or design probiotic supplements that can synthesize folate in the colon, improving overall health. Therefore, bifidobacteria (alone or in association with other microorganisms) may, in the future, contribute to reducing widespread folate deficiencies prevalent among vulnerable human population groups, such as older people, women at child-birth age, and people in low-income countries.

Preconception use of antibiotics and fecundability: a Danish prospective cohort study

OBJECTIVE

To assess the association between preconception antibiotic use and fecundability, the per menstrual cycle probability of conception.

DESIGN

SnartForaeldre.dk, a Danish prospective cohort study of women trying to conceive (2007-2020).

SETTING

Not applicable.

SUBJECT(S)

9462 female participants, median age 29 years at enrollment.

EXPOSURE

Antibiotic use was defined by filled prescriptions retrieved from the Danish National Prescription Registry, using Anatomical Therapeutic Chemical codes, and modeled as time-varying (menstrual cycle-varying) exposure.

MAIN OUTCOME MEASURE(S)

Pregnancy status was reported on female follow-up questionnaires every 8 weeks for up to 12 months or until conception. Fecundability ratios (FR) and 95% confidence intervals (CI) were computed using proportional probabilities regression models, with adjustment for age, partner age, education, smoking, folic acid supplementation, body mass index, parity, cycle regularity, timing of intercourse, and sexually transmitted infections.

RESULT(S)

During all cycles of observation, the percentage of participants filing at least 1 antibiotic prescription was 11.9%; 8.6% had a prescription for penicillins, 2.1% for sulfonamides, and 1.8% for macrolides. Based on life-table methods, 86.5% of participants conceived within 12 cycles of follow-up. Recent preconception antibiotic use was associated with reduced fecundability (≥1 prescription vs. none: adjusted FR = 0.86; 95% CI, 0.76-0.99). For participants using penicillins, sulfonamides, or macrolides, the adjusted FRs were 0.97 (95% CI, 0.83-1.12), 0.68 (95% CI, 0.47-0.98), and 0.59 (95% CI, 0.37-0.93), respectively.

CONCLUSION(S)

Preconception use of antibiotics, specifically sulfonamides and macrolides, was associated with decreased fecundability compared with no use. The observed associations may be explained plausibly by confounding by indication, as we lacked data on indications for the prescribed antibiotics. Consequently, we cannot separate the effect of the medication from the effect of the underlying infection.

A bacteriocyte symbiont determines whitefly sex ratio by regulating mitochondrial function

Nutritional symbionts influence host reproduction, but the underlying molecular mechanisms are largely unclear. We previously found that the bacteriocyte symbiont Hamiltonella impacts the sex ratio of the whitefly Bemisia tabaci. Hamiltonella synthesizes folate by cooperation with the whitefly. Folate deficiency by Hamiltonella elimination or whitefly gene silencing distorted whitefly sex ratio, and folate supplementation restored the sex ratio. Hamiltonella deficiency or gene silencing altered histone H3 lysine 9 trimethylation (H3K9me3) level, which was restored by folate supplementation. Genome-wide chromatin immunoprecipitation-seq analysis of H3K9me3 indicated mitochondrial dysfunction in symbiont-deficient whiteflies. Hamiltonella deficiency compromised mitochondrial quality of whitefly ovaries. Repressing ovary mitochondrial function led to distorted whitefly sex ratio. These findings indicate that the symbiont-derived folate regulates host histone methylation modifications, which thereby impacts ovary mitochondrial function, and finally determines host sex ratio. Our study suggests that a nutritional symbiont can regulate animal reproduction in a way that differs from reproductive manipulators.

Prevalence of vitamin B complex deficiencies in women in reproductive age, pregnant, or lactating woman in Brazil: a systematic review and meta-analysis protocol

BACKGROUND

Vitamin B deficiencies are involved with several outcomes in fertility and pregnancy. In Brazil, the national prevalence rates of these micronutrient deficiencies in women of reproductive age were not known. This study aims to systematically identify, select, evaluate, analyze, and report the prevalence rates of vitamin B complex deficiencies in women of reproductive age in Brazil and identify variables that may modify the outcome rates.

METHODS

A systematic review will be conducted guided by the following question: "What is the prevalence of vitamin B deficiencies in women of reproductive age in Brazil?". The studies will be identified and selected from a literature search using electronic databases, consultation with researchers/specialists, and reference lists of eligible studies and reviews on the topic. Major eligibility criteria include observational cross-sectional and cohort studies carried out in Brazil and performed in women 10-49 years old, or pregnant and lactating mothers, and investigated the deficiency of vitamin B complex by laboratory test. Two reviewers independently will perform the screening and selection of the studies, data extraction, and risk of bias assessment. For the data report, a narrative approach will be used to present the characteristics of the included studies and individual findings. A random meta-analysis model will be implemented to summarize the individual prevalence rates in a global value if the studies are sufficiently homogeneous.

DISCUSSION

This study aims to identify the national and regional prevalence rates of vitamin B complex deficiencies in women of reproductive age; allow the policymakers discuss, plan, and implement public policies to screen; and prevent and/or treat these malnutrition conditions. This also aims to know the rates of nutritional deficiencies over the years, serving as an indirect indicator of the socioeconomic and dietary patterns of the population. Specifically for folate, this study allows to compare the prevalence rates of deficiency of this vitamin before and after the mandatory fortification of wheat and corn flours implemented since 2004 in Brazil, in this specific population. The evidence gathered may highlight the need for population-based studies to investigate the deficiency of these vitamins.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42020188474.

B vitamins, polycystic ovary syndrome, and fertility

PURPOSE OF REVIEW

This review provides a general overview of the literature on B vitamins and fertility, as well as summarizes the evidence concerning B vitamin supplementation and fertility among polycystic ovary syndrome (PCOS) women.

RECENT FINDINGS

Studies among women conceiving with and without medical assistance provide strong evidence for a beneficial effect of B vitamins, particularly folate and vitamin B12, on fecundability and fertility. Moreover, recent work suggests that effects may be even more pronounced among women with menstrual cycle dysfunction (a common symptom of PCOS). Among PCOS women, intervention studies have demonstrated that folic acid supplementation may reduce homocysteine levels, potentially improve women's metabolic profiles, and possibly ameliorate some hallmark features of PCOS. Although none of these intervention studies have included fertility endpoints, it is possible that by reducing homocysteine levels (or other clinical/biochemical features) in PCOS women, there may be a downstream improvement in fertility outcomes.

SUMMARY

There is growing evidence folate (and possibly vitamin B12) supplementation may be beneficial to fertility in women. Although most studies have not exclusively focused on women with PCOS, there is biological plausibility and some evidence that B vitamin supplementation may be even more important for improving reproductive health outcomes in PCOS women.

Identification of Active Compounds against Melanoma Growth by Virtual Screening for Non-Classical Human DHFR Inhibitors

Antifolates such as methotrexate (MTX) have been largely known as anticancer agents because of their role in blocking nucleic acid synthesis and cell proliferation. Their mechanism of action lies in their ability to inhibit enzymes involved in the folic acid cycle, especially human dihydrofolate reductase (hDHFR). However, most of them have a classical structure that has proven ineffective against melanoma, and, therefore, inhibitors with a non-classical lipophilic structure are increasingly becoming an attractive alternative to circumvent this clinical resistance. In this study, we conducted a protocol combining virtual screening (VS) and cell-based assays to identify new potential non-classical hDHFR inhibitors. Among 173 hit compounds identified (average logP = 3.68; average MW = 378.34 Da), two-herein, called C1 and C2-exhibited activity against melanoma cell lines B16 and A375 by MTT and Trypan-Blue assays. C1 showed cell growth arrest (39% and 56%) and C2 showed potent cytotoxic activity (77% and 51%) in a dose-dependent manner. The effects of C2 on A375 cell viability were greater than MTX (98% vs 60%) at equivalent concentrations and times. Our results indicate that the integrated in silico/in vitro approach provided a benchmark to identify novel promising non-classical DHFR inhibitors showing activity against melanoma cells.

Dietary Intake and Genetic Background Influence Vitamin Needs during Pregnancy

Numerous approaches demonstrate how nutritional intake can be sufficient to ensure the necessary supply of vitamins. However, it is evident that not all vitamins are contained in all foods, so it is necessary either to combine different food groups or to use a vitamin supplement to be well-fed. During pregnancy, deficiencies are often exacerbated due to increased energy and nutritional demands, causing adverse outcomes in mother and child. Micronutrient supplementation could lead to optimal pregnancy outcomes being essential for proper metabolic activities that are involved in tissue growth and functioning in the developing fetus. In order to establish adequate vitamin supplementation, various conditions should be considered, such as metabolism, nutrition and genetic elements. This review accurately evaluated vitamin requirements and possible toxic effects during pregnancy. Much attention was given to investigate the mechanisms of cell response and risk assessment of practical applications to improve quality of life. Importantly, genetic studies suggest that common allelic variants and polymorphisms may play an important role in vitamin metabolism during pregnancy. Changes in gene expression of different proteins involved in micronutrients’ metabolism may influence the physiological needs of the pregnant woman.

Folate metabolism abnormalities in infertile patients with endometriosis

Background: Homocysteine levels can be impacted by enzymes variations. Aim: To correlate MTHFR, MTR and MTRR variants with homocysteine levels in the blood and follicular fluid and assisted reproduction results. Material & methods: MTHFR (rs2274976, rs1801131, rs1801133), MTR (rs1805087) and MTRR (rs1801394) genotyping was performed by TaqMan assays and compared with homocysteine levels, measured by ELISA, to oocytes retrieved and to the pregnancy status of women with endometriosis and controls. Results: The MTR G allele and GG genotype were more common in patients with endometriosis. They also showed lower levels of homocysteine and more clinical gestations. Epistasis analysis showed a model associated with gestational results, composed of MTHFR+MTR variants (CC+AG). Conclusion: The summation effect of variants in genes participating in folate metabolism was associated with pregnancy status in Brazilian women. MTR variants were more observed in endometriosis patients, as well as lower follicular Hcy levels and increased clinical pregnancy results.

Trichloroethylene modifies energy metabolites in the amniotic fluid of Wistar rats

Exposure to trichloroethylene (TCE), an industrial solvent, is associated with several adverse pregnancy outcomes in humans and decreased fetal weight in rats. However, effects of TCE on energy metabolites in amniotic fluid, which have associations with pregnancy outcomes, has not been published previously. In the current exploratory study, timed-pregnant Wistar rats were exposed to 480 mg TCE/kg/day via vanilla wafer or to vehicle (wafer) alone from gestational day (GD) 6-16. Amniotic fluid collected on GD 16 was analyzed for metabolites important in energy metabolism using short chain fatty acid and tricarboxylic acid plus platforms (N = 4 samples/sex/treatment). TCE decreased concentrations of the following metabolites in amniotic fluid for both fetal sexes: 6-phosphogluconate, guanosine diphosphate, adenosine diphosphate, adenosine triphosphate, and flavin adenine dinucleotide. TCE decreased fructose 1,6-bisphosphate and guanosine triphosphate concentrations in amniotic fluid of male but not female fetuses. Moreover, TCE decreased uridine diphosphate-D-glucuronate concentrations, and increased arginine and phosphocreatine concentrations, in amniotic fluid of female fetuses only. No metabolites were increased in amniotic fluid of male fetuses. Pathway analysis suggested that TCE altered folate biosynthesis and pentose phosphate pathway in both sexes. Using metabolite ratios to investigate changes within specific pathways, some ratio alterations, including those in arginine metabolism and phenylalanine metabolism, were detected in females only. Ratio analysis also suggested enzymes, including gluconokinase, as potential TCE targets. Together, results from this exploratory study suggest that TCE differentially modified energy metabolites in amniotic fluid based on sex. These findings may inform future studies of TCE reproductive toxicity.

Folic Acid, Folinic Acid, 5 Methyl TetraHydroFolate Supplementation for Mutations That Affect Epigenesis through the Folate and One-Carbon Cycles

Methylation is an essential biochemical mechanism that is central to the transmission of life, and crucially responsible for regulating gametogenesis and continued embryo development. The methylation of DNA and histones drives cell division and regulation of gene expression through epigenesis and imprinting. Brain development and its maturation also depend on correct lipid methylation, and continued neuronal function depends on biogenic amines that require methylation for their synthesis. All methylation processes are carried out via a methyltransferase enzyme and its unique co-factor S-adenosylmethionine (SAM); the transfer of a methyl group to a target molecule results in the release of SAH (SA homocysteine), and then homocysteine (Hcy). Both of these molecules are toxic, inhibiting methylation in a variety of ways, and Hcy recycling to methionine is imperative; this is achieved via the one carbon cycle, supported by the folates cycle. Folate deficiency causes hyperhomocysteinaemia, with several associated diseases; during early pregnancy, deficiency interferes with closure of the neural tube at the fourth week of gestation, and nutraceutical supplementation has been routinely prescribed to prevent neural tube defects, mainly involving B vitamins, Zn and folates. The two metabolic pathways are subject to single nucleotide polymorphisms that alter their activity/capacity, often severely, impairing specific physiological functions including fertility, brain and cardiac function. The impact of three types of nutraceutical supplements, folic acid (FA), folinic acid (FLA) and 5 Methyl THF (MTHF), will be discussed here, with their positive effects alongside potentially hazardous secondary effects. The issue surrounding FA and its association with UMFA (unmetabolized folic acid) syndrome is now a matter of concern, as UMFA is currently found in the umbilical cord of the fetus, and even in infants’ blood. We will discuss its putative role in influencing the acquisition of epigenetic marks in the germline, acquired during embryogenesis, as well as the role of FA in the management of cancerous disease.

Dietary folate intake and fecundability in two preconception cohorts

STUDY QUESTION

To what extent is dietary folate intake and total folate intake (dietary and supplemental intakes) associated with fecundability, the per cycle probability of conception?

SUMMARY ANSWER

Preconception dietary folate intake was positively associated with fecundability in a monotonic pattern.

WHAT IS KNOWN ALREADY

Supplemental folic acid has been associated with improved fertility, but little is known about the relation between dietary folate and fecundability.

STUDY DESIGN, SIZE, DURATION

A prospective cohort study including 9559 women trying to conceive without fertility treatment and enrolled in the period 2013-2020.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We used data from two internet-based prospective cohort studies of pregnancy planners from Denmark, where folic acid fortification is not performed (SnartForældre.dk (SF); n = 3755) and North America, where the food supply is fortified with folic acid (Pregnancy Study Online (PRESTO); n = 5804). Women contributed menstrual cycles at risk until they reported conception or experienced a censoring event. We used proportional probabilities regression models to compute fecundability ratios (FRs) and 95% CI, adjusting for potential confounders.

MAIN RESULTS AND THE ROLE OF CHANCE

Compared with a dietary folate intake ≥400 µg/day, the adjusted FRs for women in SF were 0.92 (95% CI: 0.85-0.99) for intake 250-399 µg/day, and 0.80 (95% CI: 0.68-0.94) for intake of <250 µg/day. The corresponding FRs in PRESTO were 0.95 (95% CI: 0.89-1.01) and 0.81 (95% CI: 0.65-1.00). Compared with the highest level of total folate intake (diet folate ≥400 µg/day plus folic acid supplementation), in both cohorts fecundability was lowest among women with the lowest dietary intake <250 µg/day dietary folate and no supplementation (FR: 0.76, 95% CI: 0.59-0.98 [SF] and 0.49, 95% CI: 0.31-0.77 [PRESTO]). Further, total intake dietary folate <250 µg/day plus supplementation was associated with reduced fecundability for SF participants (FR; 0.79, 95% CI: 0.65-0.98) and for PRESTO participants (FR; 0.92, 95% CI: 0.72-1.16).

LIMITATIONS, REASONS FOR CAUTION

It is unknown whether dietary folate and folic acid intake affect fecundability on its own or if there is an interaction with other micronutrients provided in healthy diet. Thus, the observed associations may not reflect dietary folate intake alone, but overall healthy diet.

WIDER IMPLICATIONS OF THE FINDINGS

Recommendations for preconception dietary folate intake and folic acid supplementation are of importance not only to prevent neural tube defects but also to enhance fecundability.

STUDY FUNDING/COMPETING INTEREST(S)

The study was supported by the National Institute of Child Health and Human Development (R01-HD086742). The authors report no competing interests.

TRIAL REGISTRATION NUMBER

N/A.

Female Fertility and the Nutritional Approach: The Most Essential Aspects

Infertility is an increasing problem that affects couples attempting pregnancy. A growing body of evidence points to a link between diet and female fertility. In fact, data show that a diet high in trans fats, refined carbohydrates, and added sugars can negatively affect fertility. Conversely, a diet based on the Mediterranean dietary patterns, i.e., rich in dietary fiber, omega-3 (ɷ-3) fatty acids, plant-based protein, and vitamins and minerals, has a positive impact on female fertility. An unhealthy diet can disrupt microbiota composition, and it is worth investigating whether the composition of the gut microbiota correlates with the frequency of infertility. There is a lack of evidence to exclude gluten from the diet of every woman trying to become pregnant in the absence of celiac disease. Furthermore, there are no data concerning adverse effects of alcohol on female fertility, and caffeine consumption in the recommended amounts also does not seem to affect fertility. On the other hand, phytoestrogens presumably have a positive influence on female fertility. Nevertheless, there are many unanswered questions with regard to supplementation in order to enhance fertility. It has been established that women of childbearing age should supplement folic acid. Moreover, most people experience vitamin D and iodine deficiency; thus, it is vital to control their blood concentrations and consider supplementation if necessary. Therefore, since diet and lifestyle seem to be significant factors influencing fertility, it is valid to expand knowledge in this area.

Enhancing in vitro oocyte maturation competence and embryo development in farm animals: roles of vitamin-based antioxidants – a review

Oocyte/embryo in vitro culture is one of the most important assisted reproductive technologies used as a tool for maintaining genetic resources biodiversity and the inheritance of valuable genetic resources through generations. The success of such processes affects the final goal of the in vitro culture, getting viable and healthy offspring. In common in vitro oocyte maturation and/or embryo development techniques, the development of oocytes/embryos is carried out at 5% carbon dioxide and roughly 20% atmosphere-borne oxygen ratios in cell culture incubators due to their reduced cost in comparison with low atmospheric oxygen-tension incubators. These conditions are usually accompanying by the emergence of reactive oxygen species (ROS), which can extremely damage cell membrane integrity and other vital cellular organelles, as well as genetic material. The present review mainly focuses on the antioxidant roles of different vitamins on in vitro oocyte maturation competence and embryo development in farm animals. Because, the conditions of in vitro embryo production (IVEP) are usually accompanying by the emergence of reactive oxygen species (ROS), which can extremely damage cell membrane integrity and other vital cellular organelles as well as genetic material. The use of antioxidant agents may prevent the extreme augmentation of ROS generation and enhance in vitro matured oocyte competence and embryo development. Therefore, this review aimed to provide an updated outline of the impact of antioxidant vitamin (Vit) supplementations during in vitro maturation (IVM) and in vitro fertilization (IVF) on oocyte maturation and consequent embryo development, in various domestic animal species. Thus, the enrichment of the culture media with antioxidant agents may prevent and neutralize the extreme augmentation of ROS generation and enhance the in vitro embryo production (IVEP) outcomes.

Effect of polymorphisms of MTHFR in controlled ovarian stimulation: a systematic review and meta-analysis

OBJECTIVE

Although several studies have reported a potential impact of methylenetetrahydrofolate reductase (MTHFR) polymorphisms on controlled ovarian stimulation (COS), the results remain controversial. The aim of the systematic review and meta-analysis was to evaluate the effect of MTHFR polymorphism on COS outcomes.

METHODS

PubMed, Web of Science, Embase, and Cochrane Central Register of Controlled Trials databases were searched up to December 2, 2020. COS clinical outcomes based on gene polymorphisms were included. Two reviewers independently extracted the data. The primary outcome was the number of oocytes retrieved. The secondary outcomes were the number of metaphase II (MII) oocytes, stimulation duration, basal follicle-stimulating hormone (FSH) level, FSH dosage, positive pregnancy test, ongoing pregnancy rate, clinical pregnancy rate, miscarriage rate, and live birth rate. Meta-analysis was performed using a fixed-effect model or random-effect model with Review Man 5.3.5. Mean difference (MD) with 95% confidence intervals (95%CIs) was calculated for continuous outcomes. The quality assessment of included studies was evaluated by using the Newcastle-Ottawa Scale.

RESULTS

Eleven studies were included in the systematic review, and seven studies with 2015 participants were included in the meta-analysis. Basal FSH level was significantly lower in CC homozygotes than TT homozygotes (four studies, 867 participants, MD - 0.54, 95%CI - 0.85 to - 0.23, P = 0.0006; I² = 0%) of MTHFR (rs1801133). FSH dose was significantly fewer in CC homozygotes compared with CT heterogeneous (three studies, 949 participants, MD - 75.78, 95%CI - 135.23 to - 16.33, P = 0.01; I² = 32%) or CT/TT model (three studies, 1097 participants, MD - 80.18, 95%CI - 135.54 to - 24.81, P = 0.005; I² = 42%). Differences in the oocytes retrieved and stimulation duration were insignificant. Gene variants on MTHFR (rs1801133) and MTHFR (rs1801131) were reported in ongoing pregnancy rate, clinical pregnancy rate, and live birth rate.

CONCLUSION

Studies to date indicate that polymorphisms of MTHFR could influence basal FSH level and FSH dose. The results could be useful to promote clinical practice on COS protocols. Further studies are needed to evaluate the clinical relevance of the multigene combination on COS.

Low levels of sulfur and cobalt during the pre- and periconceptional periods affect the oocyte yield of donors and the DNA methylome of preimplantation bovine embryos

Maternal nutrition is critical in mammalian development, influencing the epigenetic reprogramming of gametes, embryos, and fetal programming. We evaluated the effects of different levels of sulfur (S) and cobalt (Co) in the maternal diet throughout the pre- and periconceptional periods on the biochemical and reproductive parameters of the donors and the DNA methylome of the progeny in Bos indicus cattle. The low-S/Co group differed from the control with respect to homocysteine, folic acid, B12, insulin growth factor 1, and glucose. The oocyte yield was lower in heifers from the low S/Co group than that in the control heifers. Embryos from the low-S/Co group exhibited 2320 differentially methylated regions (DMRs) across the genome compared with the control embryos. We also characterized candidate DMRs linked to the DNMT1 and DNMT3B genes in the blood and sperm cells of the adult progeny. A DMR located in DNMT1 that was identified in embryos remained differentially methylated in the sperm of the progeny from the low-S/Co group. Therefore, we associated changes in specific compounds in the maternal diet with DNA methylation modifications in the progeny. Our results help to elucidate the impact of maternal nutrition on epigenetic reprogramming in livestock, opening new avenues of research to study the effect of disturbed epigenetic patterns in early life on health and fertility in adulthood. Considering that cattle are physiologically similar to humans with respect to gestational length, our study may serve as a model for studies related to the developmental origin of health and disease in humans.

MTHFR (methylenetetrahydrofolate reductase: EC 1.5.1.20) SNPs (single-nucleotide polymorphisms) and homocysteine in patients referred for investigation of fertility

Purpose

MTHFR, one of the major enzymes in the folate cycle, is known to acquire single-nucleotide polymorphisms that significantly reduce its activity, resulting in an increase in circulating homocysteine. Methylation processes are of crucial importance in gametogenesis, involved in the regulation of imprinting and epigenetic tags on DNA and histones. We have retrospectively assessed the prevalence of MTHFR SNPs in a population consulting for infertility according to gender and studied the impact of the mutations on circulating homocysteine levels.

Methods

More than 2900 patients having suffered at least two miscarriages (2 to 9) or two failed IVF/ICSI (2 to 10) attempts were included for analysis of MTHFR SNPs C677T and A1298C. Serum homocysteine levels were measured simultaneously.

Results

We observed no difference in the prevalence of different genetic backgrounds between men and women; only 15% of the patients were found to be wild type. More than 40% of the patients are either homozygous for one SNP or compound heterozygous carriers. As expected, the C677T SNP shows the greatest adverse effect on homocysteine accumulation. The impact of MTHFR SNPs on circulating homocysteine is different in men than in women.

Conclusions

Determination of MTHFR SNPs in both men and women must be seriously advocated in the presence of long-standing infertility; male gametes, from MTHFR SNPs carriers, are not exempted from exerting a hazardous impact on fertility. Patients should be informed of the pleiotropic medical implications of these SNPs for their own health, as well as for the health of future children.

MTHFR 1298A>C Substitution is a Strong Candidate for Analysis in Recurrent Pregnancy Loss: Evidence from 14,289 Subjects

We undertook meta-analyses on MTHFR 1298A>C substitution for critically evaluating its association with recurrent pregnancy loss (RPL). MTHFR genotype data for 5888 cases and 8401 controls from 39 studies were pooled to perform this meta-analyses. Genotype data were screened, scrutinized, pooled, analysed and subjected to sensitivity analysis to carefully evaluate the association between MTHFR 1298A>C and recurrent pregnancy loss. Genetic associations were sought using dominant, recessive and co-dominant models of genetic testing with odds ratio and 95% Confidence interval (CI) as the effect measures. Further analyses were undertaken by classifying the studies into Caucasian and East Asian sub-groups. Genetic heterogeneity was tested before pooling the data across studies. For assessing publication bias, Egger's intercept test was undertaken. We found a significant association of 1298A>C substitution with increased risk of RPL in the dominant (P=0.000; OR = 1.58; 95% CI =1.25-1.99) as well as recessive (P=0.000; OR = 1.66; 95% CI =1.25-2.20) models. In sub-group analysis, we observed a significant association of the polymorphism with RPL in the Caucasian populations using dominant (P=0.000; OR = 1.98; 95% CI =1.42-2.76) and recessive (P=0.000; OR = 2.20; 95% CI =1.49-3.24) models. However, this substitution showed no association with RPL in the East Asian populations (P=0.149; OR = 1.187; 95% CI =0.94-1.50). MTHFR 1298A>C substitution shows association with the risk of recurrent pregnancy loss. The association is in a population-specific manner with the substitution being a strong risk factor only in the Caucasian populations.

Mendelian randomisation approaches to the study of prenatal exposures: A systematic review

BACKGROUND

Mendelian randomisation (MR) designs apply instrumental variable techniques using genetic variants to study causal effects. MR is increasingly used to evaluate the role of maternal exposures during pregnancy on offspring health.

OBJECTIVES

We review the application of MR to prenatal exposures and describe reporting of methodologic challenges in this area.

DATA SOURCES

We searched PubMed, EMBASE, Medline Ovid, Cochrane Central, Web of Science, and Google Scholar.

STUDY SELECTION AND DATA EXTRACTION

Eligible studies met the following criteria: (a) a maternal pregnancy exposure; (b) an outcome assessed in offspring of the pregnancy; and (c) a genetic variant or score proposed as an instrument or proxy for an exposure.

SYNTHESIS

We quantified the frequency of reporting of MR conditions stated, techniques used to examine assumption plausibility, and reported limitations.

RESULTS

Forty-three eligible studies were identified. When discussing challenges or limitations, the most common issues described were known potential biases in the broader MR literature, including population stratification (n = 29), weak instrument bias (n = 18), and certain types of pleiotropy (n = 30). Of 22 studies presenting point estimates for the effect of exposure, four defined their causal estimand. Twenty-four studies discussed issues unique to prenatal MR, including selection on pregnancy (n = 1) and pleiotropy via postnatal exposure (n = 10) or offspring genotype (n = 20).

CONCLUSIONS

Prenatal MR studies frequently discuss issues that affect all MR studies, but rarely discuss problems specific to the prenatal context, including selection on pregnancy and effects of postnatal exposure. Future prenatal MR studies should report and attempt to falsify their assumptions, with particular attention to issues specific to prenatal MR. Further research is needed to evaluate the impacts of biases unique to prenatal MR in practice.

Maternal folate, one-carbon metabolism and pregnancy outcomes

Single nucleotide polymorphisms and pre- and peri-conception folic acid (FA) supplementation and dietary data were used to identify one-carbon metabolic factors associated with pregnancy outcomes in 3196 nulliparous women. In 325 participants, we also measured circulating folate, vitamin B12 and homocysteine. Pregnancy outcomes included preeclampsia (PE), gestational hypertension (GHT), small for gestational age (SGA), spontaneous preterm birth (sPTB) and gestational diabetes mellitus (GDM). Study findings show that maternal genotype MTHFR A1298C(CC) was associated with increased risk for PE, whereas TCN2 C766G(GG) had a reduced risk for sPTB. Paternal MTHFR A1298C(CC) and MTHFD1 G1958A(AA) genotypes were associated with reduced risk for sPTB, whereas MTHFR C677T(CT) genotype had an increased risk for GHT. FA supplementation was associated with higher serum folate and vitamin B12 concentrations, reduced uterine artery resistance index and increased birth weight. Women who supplemented with <800 μg daily FA at 15-week gestation had a higher incidence of PE (10.3%) compared with women who did not supplement (6.1%) or who supplemented with ≥800 μg (5.4%) (P < .0001). Higher serum folate levels were found in women who later developed GDM compared with women with uncomplicated pregnancies (Mean ± SD: 37.6 ± 8 nmol L-1 vs. 31.9 ± 11.2, P = .007). Fast food consumption was associated with increased risk for developing GDM, whereas low consumption of green leafy vegetables and fruit were independent risk factors for SGA and GDM and sPTB and SGA, respectively. In conclusion, maternal and paternal genotypes, together with maternal circulating folate and homocysteine concentrations, and pre- and early-pregnancy dietary factors, are independent risk factors for pregnancy complications.

One Carbon Metabolism and Mammalian Pregnancy Outcomes

One-carbon metabolism is involved in varieties of physiological processes in mammals, including nucleic acid synthesis, amino acid homeostasis, epigenetic regulation, redox balance and neurodevelopment. The current evidence linking levels of one-carbon nutrients during pregnancy to the development of oocytes, embryos, and placentas, as well as maternal and offspring health, is reviewed. The sources of mammalian one-carbon units, the pathways active in mammalian one-carbon metabolism, the maternal and fetal needs for one-carbon units and their functions during pregnancy are described. The demand for one-carbon metabolism is highest during pregnancy compared to the entire lifetime of a mammal. The primary types of one-carbon metabolism in mammals are the folate cycle, methionine cycle and transsulfuration pathway, which varies at different pregnancy stages (e.g., methylation programming of embryo, neural development of fetus, fetal growth and placenta development). Therefore, an overall consideration of one-carbon metabolism requirements for different pregnancy stages, is called for, specifically, the balance of all nutrients involved, not just one single nutrient in one-carbon metabolism. Moreover, the establishment of an ideal one-carbon metabolism requirement model is suggested according to the requirements for different pregnancy stages to support optimal pregnancy outcomes and maternal and offspring health.

Clinical Application of Antioxidants to Improve Human Oocyte Mitochondrial Function: A Review

Mitochondria produce adenosine triphosphate (ATP) while also generating high amounts of reactive oxygen species (ROS) derived from oxygen metabolism. ROS are small but highly reactive molecules that can be detrimental if unregulated. While normally functioning mitochondria produce molecules that counteract ROS production, an imbalance between the amount of ROS produced in the mitochondria and the capacity of the cell to counteract them leads to oxidative stress and ultimately to mitochondrial dysfunction. This dysfunction impairs cellular functions through reduced ATP output and/or increased oxidative stress. Mitochondrial dysfunction may also lead to poor oocyte quality and embryo development, ultimately affecting pregnancy outcomes. Improving mitochondrial function through antioxidant supplementation may enhance reproductive performance. Recent studies suggest that antioxidants may treat infertility by restoring mitochondrial function and promoting mitochondrial biogenesis. However, further randomized, controlled trials are needed to determine their clinical efficacy. In this review, we discuss the use of resveratrol, coenzyme-Q10, melatonin, folic acid, and several vitamins as antioxidant treatments to improve human oocyte and embryo quality, focusing on the mitochondria as their main hypothetical target. However, this mechanism of action has not yet been demonstrated in the human oocyte, which highlights the need for further studies in this field.

Embryonic MTHFR contributes to blastocyst development

PURPOSE

Reduction in methylenetetrahydrofolate reductase (MTHFR) activity due to genetic variations in the MTHFR gene has been controversially implicated in subfertility in human in vitro fertilization. However, there is no direct gene-knockdown study of embryonic MTHFR to assess its involvement in mammalian preimplantation development. The purpose of this study is to investigate expression profiles and functional roles of MTHFR in bovine preimplantation development.

METHODS

Reverse transcription-quantitative PCR (RT-qPCR) and analysis of publicly available RNA-seq data were performed to reveal expression levels of MTHFR during bovine preimplantation development. We knocked down MTHFR by siRNA-mediated RNA interference from the 8- to 16-cell stage and assessed the effects on preimplantation development.

RESULTS

The RT-qPCR analysis showed relatively high MTHFR expression at the GV oocyte stage, which was decreased toward the 8- to 16-cell stage and then slightly restored at the blastocyst stage. Public data-based analysis also showed the similar pattern of expression with substantial embryonic expression at the blastocyst stage. MTHFR knockdown reduced the blastocyst rate (P < 0.01) and the numbers of total (P < 0.0001), trophectoderm (P < 0.0001), and inner cell mass (P < 0.001) cells.

CONCLUSION

The results indicate that embryonic MTHFR is indispensable for normal blastocyst development. The findings provide insight into the debatable roles of MTHFR in fertility and may be applicable for the improvement of care for early embryos via modulation of surrounding folate-related nutritional conditions in vitro and/or in utero, depending on the parental and embryonic MTHFR genotype.

Folic Acid Affects Iron Status in Female Rats with Deficiency of These Micronutrients

Although simultaneous supplementation with iron and folic acid is justified, the potential interactions between these micronutrients are unknown. The aim of this study was to determine the effects of oral iron and folic acid, administered together or separately, on iron concentration in tissues in rats with a deficiency of both these micronutrients. In the first stage of the experiment (28 days), 150 8-week-old female Wistar rats were randomly assigned to a control group (C; n = 30) fed the standard diet and to a study group (n = 120) fed a diet deficit in iron and folate. The study group was then randomly divided to four groups: D group fed a deficit diet, FE group fed a deficit diet with iron gluconate, the FOL group fed a deficit diet with folate acid, and the FEFOL group fed a deficit diet with iron gluconate and folate acid. After 2, 10, and 21 days of supplementation, ten animals from each group were killed. Morphological parameters were measured in whole blood. Iron concentration was assayed in serum, liver, spleen, pancreas, heart, and kidneys. Folic acid supplementation more significantly decreased iron concentrations in the pancreas and spleen than in the D group after 10 and 21 days of supplementation. Moreover, the combination of iron with folic acid markedly decreased iron levels in the liver and spleen, in comparison with iron alone, after 10 and 21 days of the experiment. In conclusion, folic acid affects iron status in female rats deficient in these micronutrients in moderate and long-term supplementation.

Symposium review: One-carbon metabolism and methyl donor nutrition in the dairy cow

The present review focuses on methyl donor metabolism and nutrition in the periparturient and lactating dairy cow. Methyl donors are involved in one-carbon metabolism, which includes the folate and Met cycles. These cycles work in unison to support lipid, nucleotide, and protein synthesis, as well as methylation reactions and the maintenance of redox status. A key feature of one-carbon metabolism is the multi-step conversion of tetrahydrofolate to 5-methyltetrahyrofolate. Homocysteine and 5-methyltetrahyrofolate are utilized by vitamin B₁₂-dependent Met synthase to couple the folate and Met cycles and generate Met. Methionine may also be remethylated from choline-derived betaine under the action of betaine hydroxymethyltransferase. Regardless, Met is converted within the Met cycle to S-adenosylmethionine, which is universally utilized in methyl-group transfer reactions including the synthesis of phosphatidylcholine. Homocysteine may also enter the transsulfuration pathway to generate glutathione or taurine for scavenging of reactive oxygen metabolites. In the transition cow, a high demand exists for compounds with a labile methyl group. Limited methyl group supply may contribute to inadequate hepatic phosphatidylcholine synthesis and hepatic triglyceride export, systemic oxidative stress, and compromised milk production. To minimize the perils associated with methyl donor deficiency, the peripartum cow relies on de novo methylneogenesis from tetrahydrofolate. In addition, dietary supplementation of rumen-protected folic acid, vitamin B₁₂, Met, choline, and betaine are potential nutritional approaches to target one-carbon pools and improve methyl donor balance in transition cows. Such strategies have merit considering research demonstrating their ability to improve milk production efficiency, milk protein synthesis, hepatic health, and immune response. This review aims to summarize the current understanding of folic acid, vitamin B₁₂, Met, choline, and betaine utilization in the dairy cow. Methyl donor co-supplementation, fatty acid feeding strategies that may optimize methyl donor supplementation efficacy, and potential epigenetic mechanisms are also considered.

The proteome of IVF-induced aberrant embryo-maternal crosstalk by implantation stage in ewes

Background

Implantation failure limits the success of in vitro fertilization and embryo transfer (IVF-ET). Well-organized embryo-maternal crosstalk is essential for successful implantation. Previous studies mainly focused on the aberrant development of in vitro fertilized (IVF) embryos. In contrast, the mechanism of IVF-induced aberrant embryo-maternal crosstalk is not well defined.

Results

In the present study, using ewes as the model, we profiled the proteome that features aberrant IVF embryo-maternal crosstalk following IVF-ET. By comparing in vivo (IVO) and IVF conceptuses, as well as matched endometrial caruncular (C) and intercaruncular (IC) areas, we filtered out 207, 295, and 403 differentially expressed proteins (DEPs) in each comparison. Proteome functional analysis showed that the IVF conceptuses were characterized by the increased abundance of energy metabolism and proliferation-related proteins, and the decreased abundance of methyl metabolism-related proteins. In addition, IVF endometrial C areas showed the decreased abundance of endometrial remodeling and redox homeostasis-related proteins; while IC areas displayed the aberrant abundance of protein homeostasis and extracellular matrix (ECM) interaction-related proteins. Based on these observations, we propose a model depicting the disrupted embryo-maternal crosstalk following IVF-ET: Aberrant energy metabolism and redox homeostasis of IVF embryos, might lead to an aberrant endometrial response to conceptus-derived pregnancy signals, thus impairing maternal receptivity. In turn, the suboptimal uterine environment might stimulate a compensation effect of the IVF conceptuses, which was revealed as enhanced energy metabolism and over-proliferation.

Conclusion

Systematic proteomic profiling provides insights to understand the mechanisms that underlie the aberrant IVF embryo-maternal crosstalk. This might be helpful to develop practical strategies to prevent implantation failure following IVF-ET.

Dietary Intakes of Vitamin B-2 (Riboflavin), Vitamin B-6, and Vitamin B-12 and Ovarian Cycle Function among Premenopausal Women

BACKGROUND

Riboflavin, vitamin B-6, and vitamin B-12 are key players in one-carbon metabolism as enzymatic cofactors, and deficiency of these nutrients may influence reproductive outcomes possibly through affecting reproductive hormones.

OBJECTIVE

The goal was to investigate associations between dietary intakes of riboflavin, vitamin B-6, and vitamin B-12, and menstrual function among premenopausal women.

DESIGN

This was a secondary analysis of a prospective cohort study conducted at the University at Buffalo during 2005 to 2007.

PARTICIPANTS/SETTING

Participants were 259 healthy, regularly menstruating women (aged 18 to 44 years) with self-reported menstrual cycles between 21 and 35 days, who were not trying to conceive, and who had not used hormonal contraception during the past 3 months.

MAIN OUTCOME MEASURES

Intakes of B vitamins were assessed via 24-hour dietary recalls four times per menstrual cycle for two cycles. Serum reproductive hormones and plasma homocysteine were measured eight and three times, respectively, per cycle for two cycles. Anovulatory cycles were determined by progesterone concentrations ≤5 ng/mL (15.9 nmol/L) and no observed serum luteinizing hormone peak during the mid or late luteal phase visit.

STATISTICAL ANALYSIS

Weighted linear mixed regressions were used to evaluate associations between cycle-averaged B vitamin intakes and hormones and homocysteine, and generalized linear regressions for associations with anovulation. Models were adjusted for age, race, body mass index, physical activity, alternate Mediterranean diet score, intakes of total energy, protein, fiber, and folate, and percentage of energy intake from fat.

RESULTS

Higher intakes of riboflavin (per 0.1 mg increase in intake) were inversely correlated with estradiol (-0.87%, 95% CI -1.67 to -0.06) and homocysteine levels (-0.61%, 95% CI -1.10 to -0.12). Higher vitamin B-6 intakes were suggestive of higher follicle-stimulating hormone, although the results were not statistically significant (0.63% difference, 95% CI -0.03 to 1.29, per 0.1 mg increase in intake; P=0.06). Small increases in testosterone and decreases in homocysteine were found with vitamin B-12 intake. No associations were observed between intake of B vitamins and a risk of sporadic anovulation.

CONCLUSIONS

Higher intakes of riboflavin were associated with a small decrease in serum estradiol among healthy, regularly menstruating women. Higher intakes of riboflavin and vitamin B-12 were associated with lower plasma homocysteine concentrations. Overall, riboflavin, vitamin B-6, and vitamin B-12 that are one-carbon nutrients do not appear to influence the ovarian cycle among premenopausal women.

Brain Susceptibility to Methyl Donor Deficiency: From Fetal Programming to Aging Outcome in Rats

Deficiencies in methyl donors, folate, and vitamin B12 are known to lead to brain function defects. Fetal development is the most studied but data are also available for such an impact in elderly rats. To compare the functional consequences of nutritional deficiency in young versus adult rats, we monitored behavioral outcomes of cerebellum and hippocampus circuits in the offspring of deficient mother rats and in adult rats fed a deficient diet from 2 to 8 months-of-age. We present data showing that the main deleterious consequences are found in young ages compared to adult ones, in terms of movement coordination and learning abilities. Moreover, we obtained sex and age differences in the deleterious effects on these functions and on neuronal layer integrity in growing young rats, while deficient adults presented only slight functional alterations without tissue damage. Actually, the cerebellum and the hippocampus develop and maturate according to different time lap windows and we demonstrate that a switch to a normal diet can only rescue circuits that present a long permissive window of time, such as the cerebellum, whereas the hippocampus does not. Thus, we argue, as others have, for supplements or fortifications given over a longer time than the developmental period.

Chronic valproate treatment influences folliculogenesis and reproductive hormones with possible ameliorating role for folic acid in adult albino rats

Sodium Valproate (VPA) is known to have deleterious consequences on ovarian function and folliculogenesis. Folic acid (FA) is associated with the quality of many parameters in folliculogenesis. Therefore, we aimed to investigate the effects of chronic Valproate administration on ovarian morphology, folliculogenesis, reproductive hormones, and the possible protective effect of Folic acid supplementation. Forty adult female albino rats were divided into four groups and treated orally for 90 days as follows: Control group received distilled water; FA group received (folic acid 400 μg/day); VPA group received (Na Valproate 200 mg/kg/day) and VPA + FA group received (Na Valproate 200 mg/kg/day + folic acid 400 μg/day). In addition, ovaries were processed for routine histology and immunohistochemistry (TGFβ1 and PCNA) and reproductive hormones levels were measured. Results showed a significant decrease in number of follicles in VPA group, while atretic follicles increased compared with control group (P < 0.001). Interestingly, the number of follicles significantly increased in VPA + FA group compared with VPA group (P < 0.001). Also, number of atretic follicles significantly decreased in the VPA + FA group compared to the VPA group. Histochemistry score decreased for TGFβ1 and PCNA staining in VPA group compared with control group (P < 0.01). Moreover, Valproate demonstrated a significant increase in testosterone levels in VPA group than control group (P < 0.001). However, VPA group demonstrated a significant decrease in levels of estradiol, progesterone, FSH and LH levels compared with control group. These changes were partially improved in VPA + FA group. In conclusion, FA co-treatment can modulate ovarian follicular and hormonal disturbances induced by valproate, which needs further investigations to identify the precise mechanisms.

Dietary intake of nutrients involved in folate-mediated one-carbon metabolism and risk for endometrial cancer

BACKGROUND

Studies disagree as to whether intakes of folate-mediated one-carbon metabolism nutrients are associated with endometrial cancer.

METHODS

Using data from the large, prospective NIH-AARP Diet and Health Study, we used Cox proportional hazards models to evaluate endometrial cancer risk associated with calorie-adjusted dietary intake of several B vitamins and methionine. All models accounted for age, race, body mass index (BMI), smoking, oral-contraceptive use, menopausal hormone therapy use and caloric intake. We estimated associations by time from baseline (≤3 or >3 years) and stratified models by BMI (<25 or ≥25 kg/m2). During 16 years of follow-up, we identified 2329 endometrial cancer cases among 114 414 participants.

RESULTS

After adjustment for confounding, we observed increased risk for endometrial cancer with greater consumption of dietary total folate, natural folate, B2, B6 and B12 [hazard ratios (HRs) ranging from 1.14 to 1.24 for the highest quintile (Q5) vs the lowest (Q1)]. Higher intakes of total folate, natural folate, B6 and B12 continued to be associated with increased risk when limiting follow-up to >3 years from baseline. We observed risks for the highest intakes of B2 [Q5 vs Q1: HR 1.27 95% confidence interval (CI) 1.07-1.50], B12 (Q5 vs Q1: HR 1.38 CI 1.17-1.63) and methionine (Q5 vs Q1: HR 1.26 CI 1.07-1.48) among women who were overweight/obese, but not among normal/underweight women.

CONCLUSIONS

Our findings indicate that one-carbon metabolism plays a role in endometrial carcinogenesis and exploration of this role in tissue and cellular biology studies is warranted.

Metabolomic profiling of ovary in mice treated with FSH using ultra performance liquid chromatography/mass spectrometry

The growth and development of follicles are a very complex physiological process that is regulated by endocrine, autocrine and paracrine mechanisms. The effect of small molecules in follicular microenvironment on follicular growth and development has not been clearly analyzed. In the present study, the metabolic changes in ovaries of FSH-stimulated mice were investigated. Metabolomic profiling of ovary stimulated by FSH were analyzed by ultra-performance liquid chromatography/mass spectrometry and characterized by principal components analysis and orthogonal partial least squares discriminant analysis. Multivariate statistical analysis identified 21 differentially metabolites in positive ion mode and 12 in negative ion mode in the FSH-treated mice compared with the control mice. These results indicated that various types of phosphatidylcholine were changed. Furthermore, the levels of L-Glutamyl 5-phosphate, N-Acetyl-L-aspartic acid, 4-fumarylacetoacetic acid, adenylylselenate and 5′-Methylthioadenosine in the ovaries of the FSH-stimulated mice were decreased. However, the levels of 19-hydroxytestosterone and 5,10-methenyltetrahydrofolic acid were significantly increased in the positive ion mode and negative ion mode, respectively. Thirty-three differential metabolites including fatty acid metabolism, amino acid metabolism and lipid metabolism in the ovaries of mice were affected by FSH injection. The findings of our study provide a new insight into understanding the follicular development.

The association between maternal methylenetetrahydrofolate reductase C677T and A1298C polymorphism and birth defects and adverse pregnancy outcomes

Published studies indicate the MTHFR C677T and A1298C polymorphisms are associated with abnormal homocysteine levels, which may cause various pregnancy complications and birth defects. However, the results obtained from different studies have been inconsistent. Therefore, this meta-analysis explores the association between MTHFR polymorphisms and birth defects and adverse pregnancy outcomes. The PubMed, ScienceDirect, Embase, and China Biology Medicine literature databases and ClinicalTrials were searched. Analyses of public bias, meta-regression, subgroups, and sensitivity were used to ensure the robustness of our results. MTHFR C677T was significantly associated with recurrent pregnancy loss in developing countries (odds ratio [OR], 1.34; 95% confidence interval [CI], 1.20-1.50) but not in developed countries (OR, 0.87; 95% CI, 0.68-1.11). No significant relationship was found between MTHFR A1298C and recurrent pregnancy loss (OR, 1.04; 95% CI, 0.93-1.18). MTHFR C677T and A1298C were not associated with preeclampsia (OR, 1.06; 95% CI, 0.97-1.16 and OR, 1.16; 95% CI, 0.97-1.39, respectively), and C677T was not associated with placental abruption (OR, 1.03; 95% CI, 0.87-1.21), intrauterine growth retardation (OR, 1.02; 95% CI, 0.90-1.15), or congenital heart disease (OR, 1.05; 95% CI, 0.89-1.25). MTHFR C677T, but not A1298C, was associated with neural tube defects (OR, 1.24; 95% CI, 1.08-1.42) and Down syndrome (OR, 1.65; 95% CI, 1.39-1.95). CONCLUSION: Although MTHFR C677T and A1298C are significantly associated with some types of congenital defects and adverse pregnancy outcomes, the impact of these polymorphisms is moderate.

Role of homocysteine metabolism in animal reproduction: A review

Homocysteine (Hcy) is a thiol-containing essential amino acid, important for the growth of cells and tissues. Several hypotheses exist regarding Hcy toxicity in humans; Hcy is involved in protein structural modifications, oxidative stress, and neurotoxicity induction and is therefore associated with several pathological conditions in humans. In veterinary science, knowledge regarding Hcy has increased recently due to several studies; however, many aspects remain undiscovered. Many details remain unknown regarding the effect of Hcy levels on pregnancy and the optimal management of pathological conditions associated with Hcy levels during pregnancy in various species. In this review, we aimed to compile various studies on Hcy metabolism to elucidate its current status in the veterinary field, particularly for ovine, bovine, equine, porcine, canine, and feline species.

Decreased autophagy was implicated in the decreased apoptosis during decidualization in early pregnant mice

Folate deficiency is a major risk factor of birth defects. Mechanistic studies on folate deficiency resulting in birth defects have mainly focused on fetal development. There have been few studies on folate deficiency from the point of view of the mother's uterus. In our previous study, we demonstrated that folate deficiency inhibits apoptosis of decidual cells, thereby restraining decidualization of the endometrium and impairing pregnancy. In this study, we further investigated the potential mechanism by which folate deficiency decreases endometrial apoptosis during decidualization. To investigate whether endometrium autophagy was inhibited under folate deficiency during decidualization, we performed real-time PCR for endometrial LC3 and P62 on day 6 (D6) to D8 of pregnancy in mice, and both were significantly changed compared to non-folate-deficient mice. Western blots showed that LC3-II and P62 were also changed in folate-deficient mice. Compared with control mice, a few punctuate LC3-II structures were detected in the folate deficiency group by immunofluorescence. Transmission electron micrographs of decidual cells on D8 showed that there were no evident autophagosomes in the folate deficiency group. In addition, apoptosis-related protein analysis by western blotting, TUNEL staining and flow cytometry showed that decreased endometrial apoptosis on D8 of pregnancy under folate deficiency was reversed after treatment with rapamycin, an autophagy inducer. ROS measurement showed that the endometrium ROS level was reduced by folate deficiency and that rapamycin reversed this effect on day 8 of pregnancy. All the results suggest that inhibiting endometrial autophagy may be implicated in the decreased endometrial apoptosis under folate deficiency during decidualization.

Evolutionary justifications for human reproductive limitations

Common human reproductive inefficiencies have multiple etiologies. Going against chance, many effects, such as polycystic ovaries, endometriosis, and folate metabolic issues, have genetic components, while aneuploid losses arise from diverse mitotic and meiotic errors at different stages, some transitory. This can be advantageous, since greater overall survival with fewer offspring can increase reproductive success. Benefits primarily accrue to mothers, who bear most child related costs, and for whom early losses are less costly than late. Different adaptations to different situations reflect human evolutionary history. For early speciation, periodic climate extremes repeatedly reduced resources, favoring limitations while contracted populations helped fix relevant genes. Later, under better conditions, evolving social cooperation could increase fecundity faster than it added resources, further supporting reproductive suppression through mitotic aneuploidy, with very early losses minimizing maternal costs. The grandmother hypothesis suggests benefits in limiting reproduction as maternal age increased pregnancy risks in order to support grandchildren as they arrived, selecting for maternal age-related meiotic aneuploidy. Finally, with variable short-term agricultural shortages, acute reproductive responses arose through chromatin "nutrient sensor"-regulated epigenetic effects that also shifted some lethal effects earlier, reducing both maternal and mutation load costs. Overall, despite suggestions to the contrary, it is likely that human selective pressures have not decreased with civilization, but that many of the costs have been shifted to early reproduction.

An epigenetic association of malformations, adverse reproductive outcomes, and fetal origins hypothesis related effects

VACTERL, the prototype for associated congenital anomalies, also has connections with functional issues such as pregnancy losses, prematurity, growth delays, perinatal difficulties, and parental subfertility. This segues into a broader association with similar connections even in the absence of malformations. DNA methylation disturbances in the ovum are a likely cause, with epigenetic links to individual components and to folate effects before conception, explaining diverse fetal and placental findings and providing a link to fetal origin hypothesis-related effects. The association encompasses the following: (1) Pre- and periconceptual effects, with frequent fertility issues and occasional imprinting disorders. (2) Early malformations. (3) Adverse pregnancy outcomes (APOs), as above. (4) Developmental destabilization that resolves soon after birth. This potentiates other causes of association findings, introducing multiple confounders. (5) Long-term fetal origins hypothesis-related risks. The other findings are exceptional when the same malformations have Mendelian origins, supporting a distinct pathogenesis. Expressions are facilitated by one-carbon metabolic issues, maternal and fetal stress, and decreased embryo size. This may be one of the commonest causes of adverse reproductive outcomes, but multifactorial findings, variable onsets and phenotypes, and interactions with multiple confounders make recognition difficult. This association supports VACTERL as a continuum that includes isolated malformations, extends the fetal origins hypothesis, explains adverse effects linked to maternal obesity, and suggests possible interventions.

MTHFR gene methylation is associated with perceived stress in healthy young adults

BACKGROUND

Epigenetic factors have been identified in the past years as interesting candidates for psychiatric disorders and related endophenotypes. It has been found that the methylenetetrahydrofolate reductase (MTHFR) gene is associated with major depressive disorder, and the aim of the current study was to examine the possible association between perceived stress and MTHFR methylation, taking into account depressive symptoms as a covariate.

PARTICIPANTS AND METHODS

Seventy-eight healthy Colombian participants (mean age=20.9 years; SD=3.0) were evaluated with the Perceived Stress Scale and with the Patient Health Questionnaire-9 for depressive symptomatology. MTHFR methylation levels were measured with a methylation-sensitive high-resolution melting method. A multiple regression analysis (adjusting for age, sex, and depressive symptoms) was carried out to assess the association between MTHFR methylation and perceived stress scores.

RESULTS

We found a significant inverse correlation between MTHFR methylation levels and perceived stress scores (r=-0.502; P=5.9×10(-5)), which remained significant after being adjusted for age, sex, and depressive symptomatology.

CONCLUSION

To our knowledge, this is the first study that reports an association between perceived stress and MTHFR methylation levels. This report adds evidence to the emerging role of epigenetic changes in endophenotypes related to affective disorders.

No evidence for association of MTHFR 677C>T and 1298A>C variants with placental DNA methylation

Background

5,10-Methylenetetrahydrofolate reductase (MTHFR) is a key enzyme in one-carbon metabolism that ensures the availability of methyl groups for methylation reactions. Two single-nucleotide polymorphisms (SNPs) in the MTHFR gene, 677C>T and 1298A>C, result in a thermolabile enzyme with reduced function. These variants, in both the maternal and/or fetal genes, have been associated with pregnancy complications including miscarriage, neural tube defects (NTDs), and preeclampsia (PE), perhaps due to altered capacity for DNA methylation (DNAm). In this study, we assessed the association between MTHFR 677TT and 1298CC genotypes and risk of NTDs, PE, or normotensive intrauterine growth restriction (nIUGR). Additionally, we assessed whether these high-risk genotypes are associated with altered DNAm in the placenta.

Results

In 303 placentas screened for this study, we observed no significant association between the occurrence of NTDs (N = 55), PE (early-onset: N = 28, late-onset: N = 20), or nIUGR (N = 21) and placental (fetal) MTHFR 677TT or 1298CC genotypes compared to healthy pregnancies (N = 179), though a trend of increased 677TT genotype in PE/IUGR together was observed (OR 2.53, p = 0.048). DNAm was profiled in 10 high-risk 677 (677TT + 1298AA), 10 high-risk 1298 (677CC + 1298CC), and 10 reference (677CC + 1298AA) genotype placentas. Linear modeling identified no significantly differentially methylated sites between high-risk 677 or 1298 and reference placentas at a false discovery rate < 0.05 and Δβ ≥ 0.05 using the Illumina Infinium HumanMethylation450 BeadChip. Using a differentially methylated region analysis or separating cytosine-guanine dinucleotides (CpGs) by CpG density to reduce multiple comparisons also did not identify differential methylation. Additionally, there was no consistent evidence for altered methylation of repetitive DNA between high-risk and reference placentas.

Conclusions

We conclude that large-scale, genome-wide disruption in DNAm does not occur in placentas with the high-risk MTHFR 677TT or 1298CC genotypes. Furthermore, there was no evidence for an association of the 1298CC genotype and only a tendency to higher 677TT in pregnancy complications of PE/IUGR. This may be due to small sample sizes or folate repletion in our Canadian population attenuating effects of the high-risk MTHFR variants. However, given our results and the conflicting results in the literature, investigations into alternative mechanisms that may explain the link between MTHFR variants and pregnancy complications, or in populations at risk of folate deficiencies, are warranted.

Electronic supplementary material

The online version of this article (10.1186/s13148-018-0468-1) contains supplementary material, which is available to authorized users.

Primary ovarian insufficiency associated with autosomal abnormalities: from chromosome to genome-wide and beyond

OBJECTIVE

The pathophysiology of primary ovarian insufficiency (POI) is not well elucidated. Many candidate genetic aberrations are on the X-chromosome; on the contrary, many genetic perturbations are also on the autosomes. The aim of this review is to summarize the knowledge of genetic aberrations on autosomes from chromosomal rearrangement, gene abnormality, genome-wide association studies and epigenetics.

METHODS

Searches of electronic databases were performed. Articles and abstracts relevant to POI and genetic studies associated with autosomes were summarized in this interpretive literature review.

RESULTS

Various genetic aberrations located on the autosomes were found. These abnormalities are from chromosomal rearrangement, which might disrupt the critical region on chromosome loci or disturbance of the meiosis process. Specific gene aberrations are also identified. The genes that have functions in ovarian development, folliculogenesis, and steroidogenesis on autosomes are proposed to be involved from gene association studies. Gene-to-gene interaction or epistasis also might play a role in POI occurrence. Recently, genetic techniques to study the whole genome have emerged. Although no specific conclusion has been made, the studies using genome-wide association to find the specific aberration throughout the genome in POI have been published. Epigenetic mechanisms might also take part in the pathogenesis of POI.

CONCLUSIONS

The considerably complex process of POI is still not well understood. Further research is needed for gene functional validation studies to confirm the contribution of genes in POI, or additional genome-wide association studies using novel clustered regularly interspaced short palindromic repeat/Cas9 technique might make these mechanisms more comprehensible.

Implication of homocysteine in diabetes and impact of folate and vitamin B12 in diabetic population

Diabetes mellitus is an acutely debilitating ailment affecting a large population of the world. At present, over 415 million people around the world including 7 million people in Pakistan suffering from diabetes. Homocysteine is an amino acid that is inversely related to vitamin B12 and folate, and raised level of homocysteine is implicated in many adverse health conditions. In this study, the potential role of homocysteine in diabetes and the epidemiology of hyperhomocysteinaemia, and vitamin B12 and folate deficiency is reviewed along with the impact of folate and vitamin B12 in regulation of homocysteine level. Deficiency of vitamin B12 and folate is rare in developed countries and the countries which adopted fortification programs, but deficiency of these vitamins is found to be highly prevalent in developing world, particularly in Pakistan. Several studies have found an association of high homocysteine levels and diabetes, but a few studies found contrary results. Hence, further epidemiological studies are recommended for homocysteine involvement in diabetes and vitamin B12 and folate deficiency, so that an urgent action can be taken to control the hyperhomocysteinaemia and consequently the ever increasing burden of disease and specifically diabetes.

Effects of Subacute Administration of Co-Trimoxazole and Folic Acid on Ovarian Tissue in Adult Female Rats

BACKGROUND

Previous studies have reported the antifertility activities of sulfonamides. This study was designed to evaluate the effects of co-trimoxazole and its co-administration with folic acid on ovarian tissue in female rats.

METHODS

A total of 54 rats were randomly divided into 9 groups (n=6). Group I served as the control and group II (vehicle) received saline. Other groups, III to IX, received co-trimoxazole (30, 60, and 120 mg/kg; i.p.), folic acid (1 mg/kg; i.p.) or their combination for 14 days, respectively. The oocytes were obtained from each group at the end of the 14th days and scored for maturational status as germinal vesicle (GV), metaphase I (MI), or metaphase II (MII). The number of primordial follicle (PrF), primary follicle (PF), and secondary follicle in formalin-fixed ovaries were counted under light microscopy. The data were analyzed by one-way ANOVA followed by post-hoc Dunnet test using SPSS statistical software (version 17.0). Results were considered statistically significant at P<0.05.

RESULTS

Co-trimoxazole (60 and 120 mg/kg) treatment for 14 days caused a significant decrease in the number of GV (P=0.02, P<0.001), MI and MII (P=0.03, P<0.001), a significant increase in structural abnormalities, including PrF, PF and secondary follicle (P<0.001) as well as congestion, inflammation and necrosis of ovarian tissue compared to the vehicle group. Folic acid co-administration with co-trimoxazole reversed partially all these parameters compared to the co-trimoxazole group (P<0.001).

CONCLUSION

The data showed the adverse effects of co-trimoxazole on the ovarian maturational status and tissue structure which was reversed partially by folic acid co-administration in rats.

Folate dietary insufficiency and folic acid supplementation similarly impair metabolism and compromise hematopoiesis

While dietary folate deficiency is associated with increased risk for birth defects and other diseases, evidence suggests that supplementation with folic acid can contribute to predisposition to some diseases, including immune dysfunction and cancer. Herein, we show that diets supplemented with folic acid both below and above the recommended levels led to significantly altered metabolism in multiple tissues in mice. Surprisingly, both low and excessive dietary folate induced similar metabolic changes, which were particularly evident for nucleotide biosynthetic pathways in B-progenitor cells. Diet-induced metabolic changes in these cells partially phenocopied those observed in mice treated with anti-folate drugs, suggesting that both deficiency and excessive levels of dietary folic acid compromise folate-dependent biosynthetic pathways. Both folate deficiency and excessive dietary folate levels compromise hematopoiesis, resulting in defective cell cycle progression, persistent DNA damage, and impaired production of lymphocytes. These defects reduce the reconstitution potential in transplantation settings and increase radiation-induced mortality. We conclude that excessive folic acid supplementation can metabolically mimic dietary folate insufficiency, leading to similar functional impairment of hematopoiesis.

Impact of folic acid intake during pregnancy on genomic imprinting of IGF2/H19 and 1-carbon metabolism

Folic acid is an essential component of 1-carbon metabolism, which generates methyl groups for DNA methylation. Disruption of genomic imprinting leads to biallelic expression which may affect disease susceptibility possibly reflected in high levels of S-adenosyl-homocysteine (SAH) and low levels of S-adenosyl-methionine (SAM). We investigated the association between folic acid supplementation during pregnancy and loss of imprinting (LOI) of IGF2 and H19 genes in placentas and cord blood of 90 mother-child dyads in association with the methylenetetrahydrofolate reductase (MTHFR) genotype. Pyrosequencing was used to evaluate deviation from monoallelic expression among 47 placentas heterozygous for H19 and 37 placentas and cord blood tissues heterozygous for IGF2 and H19 methylation levels of 48 placentas. We detected relaxation of imprinting (ROI) and LOI of H19 in placentas not associated with differences in methylation levels of the H19ICR. Placentas retained monoallelic allele-specific gene expression of IGF2, but 32.4% of cord blood samples displayed LOI of IGF2 and 10.8% showed ROI. High SAH levels were significantly associated with low H19 methylation. An interesting positive association between SAM/SAH ratio and high H19 methylation levels was detected among infants with low B₁₂ levels. Our data suggest profound differences in regulation of imprinting in placenta and cord blood; a lack of correlation of the methylome, transcriptome, and proteome; and a complex regulatory feedback network between free methyl groups and genomic imprinting at birth.-Tserga, A., Binder, A. M., Michels, K. B. Impact of folic acid intake during pregnancy on genomic imprinting of IGF2/H19 and 1-carbon metabolism.

Folate, homocysteine and the ovarian cycle among healthy regularly menstruating women

STUDY QUESTION

How are concentrations of plasma homocysteine and serum folate associated with reproductive hormones and anovulation in regularly menstruating women?

SUMMARY ANSWER

Higher homocysteine was associated with sporadic anovulation and hormonal changes that may be indicative of impaired ovulatory function, but higher serum folate was associated only with higher luteal phase progesterone.

WHAT IS KNOWN ALREADY

Higher folate levels as well as some variants in genes relevant to one-carbon metabolism, are associated with improved reproductive outcomes and responses to fertility treatment, but only a few small studies have explored the relationship between markers of one-carbon metabolism and menstrual cycle characteristics.

STUDY DESIGN, SIZE, DURATION

The BioCycle Study (2005-2007) is a prospective, longitudinal cohort of 259 regularly menstruating women not using hormonal contraceptives or dietary supplements who were followed for up to two menstrual cycles.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Serum folate and reproductive hormones were measured up to eight times per cycle and plasma homocysteine up to three times. Linear mixed models were used to estimate associations between serum folate or plasma homocysteine and log-transformed reproductive hormone levels while accounting for multiple observations and cycles per woman. Generalized estimating equations were used to examine risk of sporadic anovulation. All models were adjusted for age, race, body mass index, cigarette and alcohol use, and energy and fiber intake.

MAIN RESULTS AND THE ROLE OF CHANCE

Higher plasma homocysteine concentrations were associated with lower total estradiol across the cycle (adjusted percent change per unit increase in homocysteine [aPC] -2.3%, 95% CI: -4.2, -0.03), higher follicle stimulating hormone around the time of expected ovulation (aPC 2.4%, 95% CI: 0.2, 4.7) and lower luteal phase progesterone (aPC -6.5%, 95% CI: -11.1, -1.8). Higher serum folate concentrations were associated with higher luteal phase progesterone (aPC per unit increase in folate 1.0%, 95% CI: 0.4, 1.6). Higher homocysteine concentrations at expected ovulation were associated with a 33% increased risk of sporadic anovulation. We observed no risk associated with decreased folate concentrations, but a higher ratio of folate to homocysteine at ovulation was associated with a 10% decreased risk of anovulation.

LIMITATIONS, REASONS FOR CAUTION

Our results are generalizable to healthy women with adequate serum folate levels. The independent influence of homocysteine should be confirmed in larger cohorts and among women with folate deficiency or increased risks of anovulation.

WIDER IMPLICATIONS OF THE FINDINGS

If these findings are confirmed, it is possible that lowering homocysteine with B-vitamins through diet or supplementation could improve ovulatory function in some women.

Study FUNDING/COMPETING INTEREST(S)

This work was supported by the Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health (Contract numbers: HHSN275200403394C, HHSN275201100002I and Task one HHSN27500001). None of the authors has any conflicts of interest to disclose.

Compliance to the recommended use of folic acid supplements for women in Sweden is higher among those under treatment for infertility than among fertile controls and is also related to socioeconomic status and lifestyle

Background: Folate has been discussed in relation to fertility among women, but studies on women under treatment for infertility are lacking.

Objective: The objective of this study was to investigate folic acid supplement use and folate status among women under treatment for infertility (hereafter infertile) and fertile women also in regard to socioeconomic and lifestyle factors.

Design: Lifestyle and dietary habits, and use of dietary supplements were assessed using a questionnaire. Blood samples were obtained for analysis of folate status. 24-hour recall interviews were also performed.

Results: Highly educated, employed and infertile women were most prone to using folic acid supplements. The infertile women had a significantly better folate status than the fertile women. Folate status did not correlate with socioeconomic or lifestyle factors. The infertile women were physically more active, smoked less and were employed. Our questionnaire data had only fair agreement with the data from 24-hour recalls, but the folate status data was clearly correlated to our questionnaire results.

Conclusions: Infertile women were most prone to using folic acid supplements and had better folate status than the controls. High educational and employment status were found to be key factors for high compliance to the recommended use folic acid supplements.

Hypermethylation of AKT2 gene is associated with neural-tube defects in fetus

INTRODUCTION

Neural-tube defects (NTDs) are common birth defects of complex etiology. Although many studies have confirmed a genetic component, the exact mechanism between DNA methylation and NTDs remains unclear.

METHODS

In this work, we investigated the alteration of methylation from placental tissues obtained from 152 normal infants or with NTDs in 130 children with neural-tube defects. Genome-wide changes in DNA methylation were measured using the NimbleGen microarray. The expression levels of 12 genes were also determined, and two genes (AKT2 and CDC25C) showed low expression in NTDs by quantitative real-time PCR analysis. Then, the methyhlated region of AKT2 promoter sequences were confirmed by massARRAY.

RESULTS

A total of 150 differentially methylated regions (81 low methylated regions and 69 high methylated regions) were selected by microarray. The expression levels of AKT2 and CDC25C showed lower expression in NTDs. And the percentage of methyhlated region of AKT2 promoter were increased in NTDs.

CONCLUSIONS

DNA mythelation was one of the possible epigenetic variations correlated with the occurrence of NTDs, and AKT2 may be a candidate gene for NTDs.