The nature of the growth pattern and of the metabolic response to fasting in the rat are dependent upon the dietary protein and folic acid intakes of their pregnant dams and post-weaning fat consumption

Maternal folate and metabolic programming of the offspring: A systematic review of the literature

There is emerging evidence suggesting that folate status during pregnancy may play a role in fetal programming of metabolic disease. Therefore, this systematic review aims to summarize and systematize the current evidence surrounding the relationship between maternal folate status during pregnancy and offspring metabolic programming, focusing on both animal and human studies. PubMed, Web of Science and Scopus databases were searched in order to identify studies conducted on pregnant women or in animals studying the association between maternal folate exposure and at least one metabolic syndrome outcome in offspring after birth (weight, blood pressure, glucose regulation parameters, triglycerides and high-density lipoprotein cholesterol (HDL-C) levels). The quality of included studies was assessed using SYRCLE Risk of Bias Tools for animal studies and NHLBI Study Quality Assessment Tools for observational studies and randomized controlled trials. Among the 10 "good" or "fair" studies that investigated excessive folate exposure during the perigestational period, 7 animal studies and 1 human study reported a positive association with development of metabolic outcomes in offspring. On the other hand, 6 of the 7 "good" or "fair" included human studies compared adequate versus low folate exposure, showing a lack of association (n = 3) or a protective effect (n = 3) regarding offspring's dysmetabolism. In conclusion, there is strong evidence from animal trials suggesting that excessive folate intake in early phases of development programs for metabolic dysfunction. While human evidence regarding excessive maternal folate exposure is currently scarce, human studies suggest that folate adequacy in pregnancy is not detrimental for metabolic function of the offspring.

Transcriptome and epigenome analysis of porcine embryos from non-esterified fatty acid-exposed oocytes

Increasing evidence indicates that maternal malnutrition leads to decreased female fertility and dysregulated metabolic homeostasis in offspring. High levels of non-esterified fatty acids (NEFAs) in follicular fluid were reported to be involved in these maternal nutritional effects, but the mechanisms remain unclear. This study explored the mechanisms of action of abnormal NEFA levels during porcine oocyte in vitro maturation (IVM) on early embryo development (blastocysts) using phenotypic, transcriptomic, and epigenetic analysis. The oocytes were treated during IVM with, in addition to the 1% (v/v) porcine follicular fluid in the control group, a combination of 468 μmol/L palmitic acid, 194 μmol/L stearic acid, and 534 μmol/L oleic acid supplemented to North Carolina State University-23 (NCSU-23) maturation medium to achieve a high level of NEFAs. After IVM, oocytes were in vitro fertilized and then cultured in regular conditions for blastocysts. Expanded blastocysts were collected to complete transcriptomic and epigenetic analysis. Macroscopically, high level of NEFAs impaired embryo development by reducing the blastocyst rate. Analysis of the transcriptome revealed that pathways related to inflammation, apoptosis, metabolism, and oxidative stress were the most affected. Moreover, DNA methylation data demonstrated differentially methylated regions in genes related to cellular metabolism and inflammation processes. Therefore, our conclusion is that high level of NEFAs during IVM might affect porcine early embryo development by diminishing blastocyst rate and altering gene expression, especially at the metabolism and cell status levels, which could further decrease the embryo quality.

Reporting animal research: Explanation and elaboration for the ARRIVE guidelines 2.0

Improving the reproducibility of biomedical research is a major challenge. Transparent and accurate reporting is vital to this process; it allows readers to assess the reliability of the findings and repeat or build upon the work of other researchers. The ARRIVE guidelines (Animal Research: Reporting In Vivo Experiments) were developed in 2010 to help authors and journals identify the minimum information necessary to report in publications describing in vivo experiments. Despite widespread endorsement by the scientific community, the impact of ARRIVE on the transparency of reporting in animal research publications has been limited. We have revised the ARRIVE guidelines to update them and facilitate their use in practice. The revised guidelines are published alongside this paper. This explanation and elaboration document was developed as part of the revision. It provides further information about each of the 21 items in ARRIVE 2.0, including the rationale and supporting evidence for their inclusion in the guidelines, elaboration of details to report, and examples of good reporting from the published literature. This document also covers advice and best practice in the design and conduct of animal studies to support researchers in improving standards from the start of the experimental design process through to publication.

Down-regulation of placental folate transporters in intrauterine growth restriction

Folate deficiency in pregnancy is associated with neural tube defects, restricted fetal growth and fetal programming of diseases later in life. Fetal folate availability is dependent on maternal folate levels and placental folate transport capacity, mediated by two key transporters, Folate Receptor-α and Reduced Folate Carrier (RFC). We tested the hypothesis that intrauterine growth restriction (IUGR) is associated with decreased folate transporter expression and activity in isolated syncytiotrophoblast microvillous plasma membranes (MVM). Women with pregnancies complicated by IUGR (birth weight <3rd percentile, mean birth weight 1804±110 g, gestational age 35.7±0.61 weeks, n=25) and women delivering an appropriately-for gestational age infant (control group, birth weight 25th-75th centile, mean birth weight 2493±216 g, gestational age 33.9±0.95 weeks, n=19) were recruited and placentas were collected at delivery. MVM was isolated and folate transporter protein expression was measured using Western blot and transporter activity was determined using radiolabelled methyltetrahydrofolic acid and rapid filtration. Whereas the expression of FR-α was unaffected, MVM RFC protein expression was significantly decreased in the IUGR group (-34%, P<.05). IUGR MVM had a significantly lower folate uptake compared to the control group (-38%, P<.05). In conclusion, placental folate transport capacity is decreased in IUGR, which may contribute to the restricted fetal growth and intrauterine programming of childhood and adult disease. These findings suggest that continuation of folate supplementation in the second and third trimester is of particular importance in pregnancies complicated by IUGR.

The study design elements employed by researchers in preclinical animal experiments from two research domains and implications for automation of systematic reviews

Systematic reviews are increasingly using data from preclinical animal experiments in evidence networks. Further, there are ever-increasing efforts to automate aspects of the systematic review process. When assessing systematic bias and unit-of-analysis errors in preclinical experiments, it is critical to understand the study design elements employed by investigators. Such information can also inform prioritization of automation efforts that allow the identification of the most common issues. The aim of this study was to identify the design elements used by investigators in preclinical research in order to inform unique aspects of assessment of bias and error in preclinical research. Using 100 preclinical experiments each related to brain trauma and toxicology, we assessed design elements described by the investigators. We evaluated Methods and Materials sections of reports for descriptions of the following design elements: 1) use of comparison group, 2) unit of allocation of the interventions to study units, 3) arrangement of factors, 4) method of factor allocation to study units, 5) concealment of the factors during allocation and outcome assessment, 6) independence of study units, and 7) nature of factors. Many investigators reported using design elements that suggested the potential for unit-of-analysis errors, i.e., descriptions of repeated measurements of the outcome (94/200) and descriptions of potential for pseudo-replication (99/200). Use of complex factor arrangements was common, with 112 experiments using some form of factorial design (complete, incomplete or split-plot-like). In the toxicology dataset, 20 of the 100 experiments appeared to use a split-plot-like design, although no investigators used this term. The common use of repeated measures and factorial designs means understanding bias and error in preclinical experimental design might require greater expertise than simple parallel designs. Similarly, use of complex factor arrangements creates novel challenges for accurate automation of data extraction and bias and error assessment in preclinical experiments.

Maternal folate deficiency causes inhibition of mTOR signaling, down-regulation of placental amino acid transporters and fetal growth restriction in mice

Maternal folate deficiency is linked to restricted fetal growth, however the underlying mechanisms remain to be established. Here we tested the hypothesis that mTOR functions as a folate sensor in vivo in mice and that maternal folate deficiency inhibits placental mTOR signaling and amino acid transporter activity and causes fetal growth restriction. Folate deficient mice had lower serum folate (−60%). In late pregnancy, fetal weight in the folate deficient group was decreased (−17%, p < 0.05), whereas placental weight, litter size and crown rump length were unaltered. Maternal folate deficiency inhibited placental mTORC1 and mTORC2 signaling and decreased trophoblast plasma membrane System A and L amino acid transporter activities and transporter isoform expression. Folate deficiency also caused a decrease in phosphorylation of specific functional readouts of mTORC1 and mTORC2 signaling in multiple maternal and fetal tissues. We have identified a novel specific molecular link between maternal folate availability and fetal growth, involving regulation of placental mTOR signaling by folate, resulting in changes in placental nutrient transport. mTOR folate sensing may have broad biological significance because of the critical role of folate in normal cell function and the wide range of disorders, including cancer, that have been linked to folate availability.

Nutriepigenomics and malnutrition

Epigenetics is defined as the modulation of gene expression without changes to the underlying DNA sequence. Epigenetic alterations, as a consequence of in utero malnutrition, may play a role in susceptibility to develop adulthood diseases and inheritance. However, the mechanistic link between epigenetic modifications and abnormalities in nutrition remains elusive. This review provides an update on the association of suboptimal nutritional environment and the high propensity to produce adult-onset chronic illnesses with a particular focus on modifications in genome functions that occur without alterations to the DNA sequence. We will mention the drivers of the phenotype and pattern of epigenetic markers set down during the reprogramming along with novel preventative and therapeutic strategies. New knowledge of epigenetic alterations is opening a gate toward personalized medicine.

Epigenetic memory in response to environmental stressors

Exposure to environmental stressors, toxicants, and nutrient deficiencies can affect DNA in several ways. Some exposures cause damage and alter the structure of DNA, but there is increasing evidence that the same or other environmental exposures, including those that occur during fetal development in utero, can cause epigenetic effects that modulate DNA function and gene expression. Some epigenetic changes to DNA that affect gene transcription are at least partially reversible (i.e., they can be enzymatically reversed after cessation of exposure to environmental agents), but some epigenetic modifications seem to persist, even for decades. To explain the effects of early life experiences (such as famine and exposures to other stressors) on the long-term persistence of specific patterns of epigenetic modifications, such as DNA methylation, we propose an analogy with immune memory. We propose that an epigenetic memory can be established and maintained in self-renewing stem cell compartments. We suggest that the observations on early life effects on adult diseases and the persistence of methylation changes in smokers support our hypothesis, for which a mechanistic basis, however, needs to be further clarified. We outline a new model based on methylation changes. Although these changes seem to be mainly adaptive, they are also implicated in the pathogenesis and onset of diseases, depending on individual genotypic background and types of subsequent exposures. Elucidating the relationships between the adaptive and maladaptive consequences of the epigenetic modifications that result from complex environmental exposures is a major challenge for current and future research in epigenetics.-Vineis, P., Chatziioannou, A., Cunliffe, V. T., Flanagan, J. M., Hanson, M., Kirsch-Volders, M., Kyrtopoulos, S. Epigenetic memory in response to environmental stressors.

Developmental origins of cardiovascular disease: Impact of early life stress in humans and rodents

The Developmental Origins of Health and Disease (DOHaD) hypothesizes that environmental insults during childhood programs the individual to develop chronic disease in adulthood. Emerging epidemiological data strongly supports that early life stress (ELS) given by the exposure to adverse childhood experiences is regarded as an independent risk factor capable of predicting future risk of cardiovascular disease. Experimental animal models utilizing chronic behavioral stress during postnatal life, specifically maternal separation (MatSep) provides a suitable tool to elucidate molecular mechanisms by which ELS increases the risk to develop cardiovascular disease, including hypertension. The purpose of this review is to highlight current epidemiological studies linking ELS to the development of cardiovascular disease and to discuss the potential molecular mechanisms identified from animal studies. Overall, this review reveals the need for future investigations to further clarify the molecular mechanisms of ELS in order to develop more personalized therapeutics to mitigate the long-term consequences of chronic behavioral stress including cardiovascular and heart disease in adulthood.

Pancreatic impairment and Igf2 hypermethylation induced by developmental exposure to bisphenol A can be counteracted by maternal folate supplementation

Increasing evidence indicates that bisphenol A (BPA), a widely manufactured environmental pollutant, can induce changes in DNA methylation paatterns, which is a potential mechanism linking this environmental exposure to disease development. We investigated the influence of developmental exposure to BPA on pancreatic DNA methylation patterns and whether maternal folate supplementation can modify the epigenetic status and pancreatic impairment induced by BPA. Our results showed that maternal dietary folate supplementation in rats exposed to BPA counteracted the observed BPA-induced pancreatic impairments in the offspring, which included disrupted insulin secretion and glucose intolerance, and impaired morphology and ultrastructure of β cells. Moreover, these pancreatic dysfunctions were shown to be associated with low expression and DNA hypermethylation of insulin-like growth factor-2 (Igf2) in islets induced by exposure to BPA during the developmental period. Importantly, maternal dietary folate supplementation was demonstrated to negate this Igf2 DNA hypermethylation in the offspring, which was consistent with the upregulation of Igf2 expression. Overall, our results suggest that early developmental exposure to BPA alters the DNA methylation of Igf2, that these altered methylation patterns are associated with impaired β-cell function in the offspring and that these effects can be counteracted by maternal folate supplementation. Copyright © 2017 John Wiley & Sons, Ltd.

[Environmental Effect In Utero for Adult Disease]

Worldwide, lifestyle-related diseases such as type 2 diabetes and cardiovascular diseases are presently the leading causes of death and disability, and their incidences tend to increase. A lifestyle-related disease has been considered mainly to be induced by specific disease susceptibility genes and lifestyle after birth. However, the steep increase in the incidences of lifestyle-related diseases is difficult to be explained only by specific genes. Presently, a new theory has been proposed. Epidemiological and animal studies have disclosed the intimate links between malnutrition in the developmental stage and lifestyle-related chronic diseases. Such studies provide the foundation and framework for a new life science, that is, the theory of developmental origins of health and diseases (DOHaD). Although much research has been carried out to elucidate the putative concepts and mechanisms that relate specific exposures in early life to the risk of chronic diseases, a complete picture still remains obscure. Historically, the world has experienced severe famines, for example, the Dutch Winter Famine, the Chinese Great Leap Forward Famine, the Leningrad Siege and the Biafran Famine. These famines showed that malnutrition in utero poses higher risks of lifestyle-related diseases. The main research point has been focused on periconceptional and perinatal undernutrition and specific nutrient deficiencies. However, presently, the number of people who are overweight and obese has been increasing. Therefore, perinatal overnutrition and specific nutrient excesses should also be examined. In addition, psychological stress, environmental chemicals and artificial reproductive techniques are other important research fields in DOHaD.

Low folate and selenium in the mouse maternal diet alters liver gene expression patterns in the offspring after weaning

During pregnancy, selenium (Se) and folate requirements increase, with deficiencies linked to neural tube defects (folate) and DNA oxidation (Se). This study investigated the effect of a high-fat diet either supplemented with (diet H), or marginally deficient in (diet L), Se and folate. Pregnant female mice and their male offspring were assigned to one of four treatments: diet H during gestation, lactation and post-weaning; diet L during gestation, lactation and post-weaning; diet H during gestation and lactation but diet L fed to offspring post-weaning; or diet L during gestation and lactation followed by diet H fed to offspring post-weaning. Microarray and pathway analyses were performed using RNA from colon and liver of 12-week-old male offspring. Gene set enrichment analysis of liver gene expression showed that diet L affected several pathways including regulation of translation (protein biosynthesis), methyl group metabolism, and fatty acid metabolism; this effect was stronger when the diet was fed to mothers, rather than to offspring. No significant differences in individual gene expression were observed in colon but there were significant differences in cell cycle control pathways. In conclusion, a maternal low Se/folate diet during gestation and lactation has more effects on gene expression in offspring than the same diet fed to offspring post-weaning; low Se and folate in utero and during lactation thus has persistent metabolic effects in the offspring.

Folic acid supplementation during pregnancy induces sex-specific changes in methylation and expression of placental 11β-hydroxysteroid dehydrogenase 2 in rats

In the placenta, 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2) limits fetal glucocorticoid exposure and its inhibition has been associated to low birth weight. Its expression, encoded by the HSD11B2 gene is regulated by DNA methylation. We hypothesized that maternal diets supplemented with folic acid (FA) during pregnancy modify the expression of placental HSD11B2 through gene methylation. Wistar rats were fed with high (8 mg/kg) or normal low (1mg/kg, control) levels of FA during pregnancy. Concentrations of mRNA and protein in placentas were determined by qRT-PCR and Western blot respectively. Methylation in five CpG sites of the placental HSD11B2 promoter (-378 to -275) was analyzed by bacterial cloning and subsequent sequencing. In the FA-supplemented group, mRNA and protein levels of 11β-HSD2 decreased by 58% and increased by 89%, respectively, only in placentas attached to males. In controls, most CpG sites were not methylated except for the CpG2 site which was 80% methylated. CpG2 methylation level increased under the FA treatment; however, only in placentas attached to females was this increase significant (113%). This change was not related to HSD11B2 expression. Fetal weight of females from FA- supplemented mothers was 6% higher than females from control mothers. In conclusion, this is the first study reporting that FA over supplementation during pregnancy modifies the placental HSD11B2 gene expression and methylation in a sex-dependent manner, suggesting that maternal diets with high content of FA can induce early sex-specific responses, which may lead to long-term consequences for the offspring.

Maternal diabetes, gestational diabetes and the role of epigenetics in their long term effects on offspring

There is a global epidemic of obesity and diabetes, and current efforts to curb the diabetes epidemic have had limited success. Epidemiological studies have highlighted increased risk of obesity, diabetes and cardiovascular complications in offspring exposed to maternal diabetes, and gestational diabetes increases the risk of diabetes in subsequent generations, thereby setting up a vicious cycle of "diabetes begetting diabetes". This relationship between maternal hyperglycaemia and long-term health in the offspring is likely to become even more important with an increasing proportion of young woman being affected by diabetes, and the number of pregnancies complicated by hyperglycaemia continuing to rise. Animal models of gestational diabetes or maternal hyperglycaemia have highlighted long-term changes in the offspring with some instances of sex bias, including increased adiposity, insulin resistance, β-cell dysfunction, hypertension, as well as other structural and functional changes. Furthermore, several of these changes appear to be transmissible to later generations through the maternal line. Epigenetic changes play an important role in regulating gene expression, especially during early development. Recent studies have identified a number of epigenetic modifications in the offspring associated with maternal hyperglycaemia. In this review, we provide an overview of the epidemiological evidence linking maternal hyperglycaemia with adverse long-term outcome in the offspring, as well as of some of the studies that explore the underlying epigenetic mechanisms. A better understanding of the pathways involved may provide novel approaches for combating this global epidemic.

Effects of intrauterine growth retardation and postnatal high-fat diet on hepatic inflammatory response in pigs

The objective of this study was to investigate the glucose and insulin response of pigs with intrauterine growth retardation (IUGR) to a high-fat (HF) feeding regimen and to observe the underlying toll-like receptor-4 (TLR4) signalling pathway. Weaned piglets with IUGR or normal birthweight (NBW) (n = 20 each) received during the whole fattening period control diets (0% lard) or HF diets (HF, 10% lard). At about 110 kg body weight, pigs were euthanised to collect hepatic samples. Compared with NBW pigs, IUGR pigs had lower daily gain and feed intake. Growth rate of pigs was increased by HF feeding. Pigs fed HF diets had lower peak concentrations of glucose and insulin, which decreased more slowly than in pigs that received the control diets. The mRNA expression abundances of peroxisome proliferator-activated receptor coactivator-1α (PGC-1α), TLR4, myeloid differentiation factor 88 (MyD88), tumour necrosis factor-α (TNF-α), interleukin 6 (IL-6) and IL-1 receptor antagonist (IL-1Rn) were significantly affected by HF feeding, and IL-6 and IL-1Rn mRNA expressions were up-regulated in IUGR pigs compared with NBW pigs. Western blot analysis indicated that HF feeding elevated the protein expressions of TLR4 signalling pathway, as TLR4, MyD88, IκB kinase β and nuclear factor-κB, and insulin signalling-related proteins, as phosphorylated insulin receptor substrate-1 and phosphorylated protein kinase B. In summary, hepatic TLR4 signalling pathway and inflammatory response induced by HF feeding played an important role in the aggravated development of insulin resistance in pigs.

Early developmental conditioning of later health and disease: physiology or pathophysiology?

Extensive experimental animal studies and epidemiological observations have shown that environmental influences during early development affect the risk of later pathophysiological processes associated with chronic, especially noncommunicable, disease (NCD). This field is recognized as the developmental origins of health and disease (DOHaD). We discuss the extent to which DOHaD represents the result of the physiological processes of developmental plasticity, which may have potential adverse consequences in terms of NCD risk later, or whether it is the manifestation of pathophysiological processes acting in early life but only becoming apparent as disease later. We argue that the evidence suggests the former, through the operation of conditioning processes induced across the normal range of developmental environments, and we summarize current knowledge of the physiological processes involved. The adaptive pathway to later risk accords with current concepts in evolutionary developmental biology, especially those concerning parental effects. Outside the normal range, effects on development can result in nonadaptive processes, and we review their underlying mechanisms and consequences. New concepts concerning the underlying epigenetic and other mechanisms involved in both disruptive and nondisruptive pathways to disease are reviewed, including the evidence for transgenerational passage of risk from both maternal and paternal lines. These concepts have wider implications for understanding the causes and possible prevention of NCDs such as type 2 diabetes and cardiovascular disease, for broader social policy and for the increasing attention paid in public health to the lifecourse approach to NCD prevention.

Feeding a protein-restricted diet during pregnancy induces altered epigenetic regulation of peroxisomal proliferator-activated receptor-α in the heart of the offspring

Impaired flexibility in the use of substrates for energy production in the heart is implicated in cardiomyopathy. We investigated the effect of maternal protein restriction during pregnancy in rats on the transcription of key genes in cardiac lipid and carbohydrate metabolism in the offspring. Rats were fed protein-sufficient or protein-restricted (PR) diets during pregnancy. Triacylglycerol concentration in adult (day 105) heart was altered by maternal protein intake contingent on post-weaning fat intake and sex. mRNA expression of peroxisomal proliferator-activated receptor (PPAR)-α and carnitine palmitoyltransferase-1 was increased by the maternal PR diet in adult, but not neonatal, offspring. PPARα promoter methylation was lower in adult and neonatal heart from PR offspring. These findings suggest that prenatal nutrition alters the future transcriptional regulation of cardiac energy metabolism in the offspring through changes in epigenetic regulation of specific genes. However, changes in gene functional changes may not be apparent in early life.

Early life nutrition, epigenetics and programming of later life disease

The global pandemic of obesity and type 2 diabetes is often causally linked to marked changes in diet and lifestyle; namely marked increases in dietary intakes of high energy diets and concomitant reductions in physical activity levels. However, less attention has been paid to the role of developmental plasticity and alterations in phenotypic outcomes resulting from altered environmental conditions during the early life period. Human and experimental animal studies have highlighted the link between alterations in the early life environment and increased risk of obesity and metabolic disorders in later life. This link is conceptualised as the developmental programming hypothesis whereby environmental influences during critical periods of developmental plasticity can elicit lifelong effects on the health and well-being of the offspring. In particular, the nutritional environment in which the fetus or infant develops influences the risk of metabolic disorders in offspring. The late onset of such diseases in response to earlier transient experiences has led to the suggestion that developmental programming may have an epigenetic component, as epigenetic marks such as DNA methylation or histone tail modifications could provide a persistent memory of earlier nutritional states. Moreover, evidence exists, at least from animal models, that such epigenetic programming should be viewed as a transgenerational phenomenon. However, the mechanisms by which early environmental insults can have long-term effects on offspring are relatively unclear. Thus far, these mechanisms include permanent structural changes to the organ caused by suboptimal levels of an important factor during a critical developmental period, changes in gene expression caused by epigenetic modifications (including DNA methylation, histone modification, and microRNA) and permanent changes in cellular ageing. A better understanding of the epigenetic basis of developmental programming and how these effects may be transmitted across generations is essential for the implementation of initiatives aimed at curbing the current obesity and diabetes crisis.

Maternal high folic acid supplement promotes glucose intolerance and insulin resistance in male mouse offspring fed a high-fat diet

Maternal nutrition may influence metabolic profiles in offspring. We aimed to investigate the effect of maternal folic acid supplement on glucose metabolism in mouse offspring fed a high-fat diet (HFD). Sixty C57BL/6 female mice were randomly assigned into three dietary groups and fed the AIN-93G diet containing 2 (control), 5 (recommended folic acid supplement, RFolS) or 40 (high folic acid supplement, HFolS) mg folic acid/kg of diet. All male offspring were fed HFD for eight weeks. Physiological, biochemical and genetic variables were measured. Before HFD feeding, developmental variables and metabolic profiles were comparable among each offspring group. However, after eight weeks of HFD feeding, the offspring of HFolS dams (Off-HFolS) were more vulnerable to suffer from obesity (p = 0.009), glucose intolerance (p < 0.001) and insulin resistance (p < 0.001), compared with the controls. Off-HFolS had reduced serum adiponectin concentration, accompanied with decreased adiponectin mRNA level but increased global DNA methylation level in white adipose tissue. In conclusion, our results suggest maternal HFolS exacerbates the detrimental effect of HFD on glucose intolerance and insulin resistance in male offspring, implying that HFolS during pregnancy should be adopted cautiously in the general population of pregnant women to avoid potential deleterious effect on the metabolic diseases in their offspring.

Metabolic effects of a high-fat diet post-weaning after low maternal dietary folate during pregnancy and lactation

SCOPE

Investigate the influence of low-folate supply during pregnancy and lactation on obesity and markers of the metabolic syndrome in offspring, and how provision of a high-fat diet post weaning may exacerbate the resultant phenotype.

METHODS AND RESULTS

Female C57Bl/6 mice were randomized to low or normal folate diets (0.4 or 2 mg folic acid/kg diet) prior to and during pregnancy and lactation. At 4 wk of age, offspring were randomized to high- or low-fat diets, weighed weekly and food intake assessed at 9 and 18 wk old. Adiposity was measured at 3 and 6 months. Plasma glucose and triacylglycerol (TAG) concentrations were measured at 6 months. Maternal folate supply did not influence adult offspring body weight or adiposity. High-fat feeding post weaning increased body weight and adiposity at 3 and 6 months (p > 0.001). Maternal low folate lowered plasma glucose (p = 0.010) but increased plasma TAG (p = 0.048). High-fat feeding post weaning increased plasma glucose and TAG (p = 0.023, p = 0.049 respectively). Offspring from folate-depleted (but not folate-adequate) dams had 30% higher TAG concentration when fed the high-fat diet from weaning (p = 0.005 for interaction).

CONCLUSION

Inadequate maternal folate intake has long-term effects on offspring metabolism, manifested as increased circulating TAG, particularly in offspring with high-fat intake post weaning.

Environment-physiology, diet quality and energy balance: the influence of early life nutrition on future energy balance

Diseases caused by impaired regulation of energy balance, in particular obesity, represent a major global health burden. Although polymorphisms, lifestyle and dietary choices have been associated with differential risk of obesity and related conditions, a substantial proportion of the variation in disease risk remains unexplained. Evidence from epidemiological studies, natural experiments and from studies in animal models has shown that a poor intra-uterine environment is associated causally with increased risk of obesity and metabolic disease in adulthood. Induction of phenotypes that increase disease risk involves the fetus receiving cues from the mother about the environment which, via developmental plasticity, modify the phenotype of the offspring to match her environment. However, inaccurate information may induce an offspring phenotype that is mismatched to the future environment. Such mismatch has been suggested to underlie increased risk of metabolic disease associated with a poor early life environment. Recent studies have shown that induction of modified phenotypes in the offspring involves altered epigenetic regulation of specific genes. Identification of a central role of epigenetics in the aetiology of obesity and metabolic disease may facilitate the development of novel therapeutic interventions and of biomarkers of disease risk.

Early environmental factors, alteration of epigenetic marks and metabolic disease susceptibility

The environmental conditions that are experienced in early life can profoundly influence human biology and long-term health. Early-life nutrition and stress are among the best documented examples of such conditions because they influence the adult risk of developing metabolic diseases, such as type 2 diabetes mellitus (T2D) and cardiovascular diseases. It is now becoming increasingly accepted that environmental compounds including nutrients can produce changes in the genome activity that in spite of not altering DNA sequence can produce important, stable and transgenerational alterations in the phenotype. Epigenetic changes, in particular DNA methylation and histone acetylation/methylation, provide a 'memory' of developmental plastic responses to early environment and are central to the generation of phenotypes and their stability throughout the life course. Their effects may only become manifest later in life, e.g. in terms of altered responses to environmental challenges.

Short- and long-term effects of a maternal low-protein diet on ventilation, O₂/CO₂ chemoreception and arterial blood pressure in male rat offspring

Maternal undernutrition increases the risk of adult arterial hypertension. The present study investigated the short- and long-term effects of a maternal low-protein diet on respiratory rhythm, O₂/CO₂ chemosensitivity and arterial blood pressure (ABP) of the offspring. Male Wistar rats were divided into two groups according to their mothers' diets during gestation and lactation: control (NP, 17% of casein) and low-protein (LP, 8% of casein) groups. Direct measurements of ABP, respiratory frequency (RF), tidal volume (V T) and ventilation (VE), as well as hypercapnia (7% CO₂) and hypoxia (7% O₂) evoked respiratory responses were recorded from the awake male offspring at the 30th and 90th days of life. Blood samples were collected for the analyses of protein, creatinine and urea concentrations. The LP offspring had impaired body weight and length throughout the experiment. At 30 d of age, the LP rats showed a reduction in the concentrations of total serum protein (approximately 24%). ABP in the LP rats was similar to that in the NP rats at 30 d of age, but it was 20% higher at 90 d of age. With respect to ventilatory parameters, the LP rats showed enhanced RF (approximately 34%) and VE (approximately 34%) at 30 d of age, which was associated with increased ventilatory responses to hypercapnia (approximately 21% in VE) and hypoxia (approximately 82% in VE). At 90 d of age, the VE values and CO₂/O₂ chemosensitivity of the LP rats were restored to the control range, but the RF values remained elevated. The present data show that a perinatal LP diet alters respiratory rhythm and O₂/CO₂ chemosensitivity at early ages, which may be a predisposing factor for increased ABP at adulthood.

Epigenetics of gestational diabetes mellitus and offspring health: the time for action is in early stages of life

The epidemic increase of type 2 diabetes and obesity in developed countries cannot be explained by overnutrition, physical inactivity and/or genetic factors alone. Epidemiologic evidence suggests that an adverse intrauterine environment, in particular a shortage or excess of nutrients is associated with increased risks for many complex diseases later in life. An impressive example for the 'fetal origins of adult disease' is gestational diabetes mellitus which usually presents in 1% to >10% of third trimester pregnancies. Intrauterine hyperglycemia is not only associated with increased perinatal morbidity and mortality, but also with increased lifelong risks of the exposed offspring for obesity, metabolic, cardiovascular and malignant diseases. Accumulating evidence suggests that fetal overnutrition (and similarly undernutrition) lead to persistent epigenetic changes in developmentally important genes, influencing neuroendocrine functions, energy homeostasis and metabolism. The concept of fetal programming has important implications for reproductive medicine. Because during early development the epigenome is much more vulnerable to environmental cues than later in life, avoiding adverse environmental factors in the periconceptional and intrauterine period may be much more important for the prevention of adult disease than any (i.e. dietetic) measures in infants and adults. A successful pregnancy should not primarily be defined by the outcome at birth but also by the health status in later life.

Developmental origins of obesity and type 2 diabetes: molecular aspects and role of chemicals

Obesity is a leading risk factor for impaired glucose tolerance and type 2 diabetes (T2D). Although the cause of the obesity epidemic is multi-factorial and not entirely clear, the recent acceleration in incidence is too rapid to be accounted for only by genetics, the wide availability of calorie-rich foods, and increasingly sedentary lifestyles. Accumulating data suggest that the important causes of the obesity epidemic may be related to developmental and early life environmental conditions. The concept of the developmental origins of health and disease (DOHaD) suggests that adverse influences early in development, particularly during intrauterine life, may result in permanent changes in the physiology and metabolism of the infant, which in turn result in an increased risk of non-communicable diseases in adulthood. For example, undernutrition during pregnancy and rapid postnatal weight gain are associated with obesity and T2D in the adult offspring. Moreover, increasing evidence suggests that early-life exposure to a wide range of chemicals has a significant impact on the causes of metabolic disorders. Although the underlying molecular mechanisms remain to be determined, these factors can affect epigenetic processes, such as DNA methylation, allowing the developmental environment to modulate gene transcription. The objective of this review article was to summarize recent progress in the biomedical implications of the DOHaD concept, focusing on the pathogenesis of obesity and T2D, and to discuss a future direction for preventive strategies from a public health perspective.

Folic acid supplementation in pregnancy: are there devils in the detail?

Maternal folic acid (FA) supplementation is well recognised to protect against neural tube defects. Folate is a critical cofactor in one-carbon metabolism involved in the epigenetic regulation of transcription that underpins development. Thus, it is possible that maternal FA supplementation may have additional, unforeseen persistent effects in the offspring. This is supported by the modification by maternal supplementation with one-carbon donors and FA of the epigenetic regulation of offspring phenotype in mutant mice. The present article reviews studies in human subjects and experimental animals of the effect of maternal FA intake and phenotypic outcomes in the offspring. Maternal FA intake was associated with a short-term increased incidence of allergy-related respiratory impairment in children and multigenerational respiratory impairment in rats. Higher maternal folate status during pregnancy was associated positively with insulin resistance in 6-year-olds. In rats, maternal FA supplementation modified hepatic metabolism and vascular function through altered transcription, in some cases underpinned by epigenetic changes. FA supplementation in pregnant rats increased mammary tumorigenesis, but decreased colorectal cancer in the offspring. Maternal FA supplementation decreased a range of congenital cardiac defects in children. These findings support the view that maternal FA supplementation induces persistent changes in a number of phenotypic outcomes in the offspring. However, the number of studies is limited and insufficient to indicate a need to change current recommendations for FA intake in pregnancy. Nevertheless, such effects should be investigated thoroughly in order to support firm conclusions about the risk of unanticipated long-term negative effects of maternal FA supplementation in humans.

Epigenetic mechanisms linking early nutrition to long term health

Traditionally it has been widely accepted that our genes together with adult lifestyle factors determine our risk of developing non-communicable diseases such as type 2 diabetes mellitus, cardiovascular disease and obesity in later life. However, there is now substantial evidence that the pre and early postnatal environment plays a key role in determining our susceptible to such diseases in later life. Moreover the mechanism by which the environment can alter long term disease risk may involve epigenetic processes. Epigenetic processes play a central role in regulating tissue specific gene expression and hence alterations in these processes can induce long-term changes in gene expression and metabolism which persist throughout the lifecourse. This review will focus on how nutritional cues in early life can alter the epigenome, producing different phenotypes and altered disease susceptibilities.

Effects of intrauterine growth retardation and maternal folic acid supplementation on hepatic mitochondrial function and gene expression in piglets

Piglets with intrauterine growth retardation (IUGR) or with normal birth weight (NBW) were selected to evaluate the effects of maternal folic acid supplementation on hepatic mitochondrial function and expression levels of genes involved in mitochondrial DNA (mtDNA) biogenesis and mitochondrial function. During gestation, primiparous Yorkshire sows were fed a Control diet (folic acid 1.3 mg/kg) or a folic acid-supplemented diet (folic acid 30 mg/kg) with 16 replicates per diet. During the 28-d lactation period, sows were fed a common diet. Compared with NBW piglets, hepatic ATP concentrations and mtDNA contents were decreased in IUGR piglets. Furthermore, IUGR piglets exhibited lower membrane potential and decreased oxygen consumption in liver mitochondria, but these parameters were not affected by maternal folic acid supplementation. Intrauterine growth retardation decreased mRNA expression abundance of peroxisomal proliferator-activated receptor-γ coactivator-1α, mitochondrial transcription factor A, uncoupling protein 3, and cytochrome c oxidase subunit I and IV. Impaired antioxidant capacity characterised by increased malondialdehyde content and decreased manganese-superoxide dismutase activity was also observed in IUGR pigs. In IUGR piglets, however, nearly all of these parameters were normalised to the level of NBW piglets when the maternal diet was supplemented with folic acid during pregnancy. Hence, maternal folic acid supplementation was proved to be an effective way to reverse the changes in gene expressions in IUGR pigs, which provided a possible nutritional strategy to improve growth development of IUGR individuals.

Molecular mechanisms underlying the fetal programming of adult disease

Adverse events in utero can be critical in determining quality of life and overall health. It is estimated that up to 50 % of metabolic syndrome diseases can be linked to an adverse fetal environment. However, the mechanisms linking impaired fetal development to these adult diseases remain elusive. This review uncovers some of the molecular mechanisms underlying how normal physiology may be impaired in fetal and postnatal life due to maternal insults in pregnancy. By understanding the mechanisms, which include epigenetic, transcriptional, endoplasmic reticulum (ER) stress, and reactive oxygen species (ROS), we also highlight how intervention in fetal and neonatal life may be able to prevent these diseases long-term.

The effect of nutrition during early life on the epigenetic regulation of transcription and implications for human diseases

Epigenetic processes which include DNA methylation, histone modification and miRNAs are integral in determining when and where specific genes are expressed. There is now increasing evidence that the epigenome is susceptible to a variety of environmental cues, such as nutrition, during specific periods of development. The changes induced by early-life nutrition may reflect an adaptive response of the foetus to environmental cues acting through the process of developmental plasticity. This may allow an organism to adjust its developmental programme resulting in long-term changes in its metabolism and physiology in order to be better matched to the future environment. However, when the future environment lies outside the anticipated range, metabolic and homoeostatic capacity will be mismatched with the environment and that individual will be at increased risk of developing a range of non-communicable diseases. Thus the environmental regulation of epigenetic processes is a central component in the developmental origins of non-communicable diseases and our understanding of these processes is, therefore, critical both for the identification of individuals at risk and for the development of new intervention strategies.

Homocysteine homeostasis in the rat is maintained by compensatory changes in cystathionine β-synthase, betaine-homocysteine methyltransferase, and phosphatidylethanolamine N-methyltransferase gene transcription occurring in response to maternal protein and folic acid intake during pregnancy and fat intake after weaning

The reactions of the methionine/homocysteine pathway are mediated by several enzymes, including phosphatidylethanolamine N-methyltransferase, cystathionine β-synthase, and betaine-homocysteine methyltransferase. Homocysteine homeostasis is regulated by these enzymes. We hypothesized here that the protein and folic acid content in the maternal diet affects methionine/homocysteine metabolism in the progeny. To test this hypothesis, pregnant rats were fed a diet with normal protein and normal folic acid levels (a modified casein-based AIN-93G diet), a protein-restricted and normal folic acid diet, a protein-restricted and folic acid-supplemented diet, or a normal protein and folic acid-supplemented diet. The progeny were fed either the modified AIN-93G diet or a high-fat lard-based diet. Progeny were analyzed for expression of the phosphatidylethanolamine N-methyltransferase, cystathionine β-synthase, and betaine-homocysteine methyltransferase genes in the liver and for serum homocysteine concentration. Interactions between prenatal and postnatal nutrition were also determined. The progeny of the dams fed the diets supplemented with folic acid showed decreased expression of all 3 genes (P < .001). An interaction effect between the protein and folic acid content in the maternal diet contributed to this down-regulation (P < .001), and the postweaning diet modified these effects. Serum homocysteine concentrations were approximately 15% higher in the male rats (P < .01), but neither prenatal nutrition nor the postweaning diet affected it significantly. We conclude that maternal diet during gestation has an important effect on the transcription level of these 3 genes, but changes in gene expression were not associated with significant changes in progeny homocysteine concentrations.

Increasing the folic acid content of maternal or post-weaning diets induces differential changes in phosphoenolpyruvate carboxykinase mRNA expression and promoter methylation in rats

Environmental exposures throughout the life course, including nutrition, may induce phenotypic and epigenetic changes. There is limited information about how timing affects the nature of such effects induced by a specific nutritional exposure. We investigated the effect of increased exposure to folic acid before birth or during the juvenile-pubertal period in rats on the epigenetic regulation of glucose homeostasis. Rats were fed either a folic acid-adequate (AF; 1 mg/kg feed) or a folic acid-supplemented (FS; 5 mg/kg feed) diet from conception until delivery and then an AF diet during lactation. Juvenile rats were fed either the AF or the FS diet from weaning for 28 d and then an AF diet. Liver and blood were collected after a 12 h fast between postnatal days 84 and 90. Maternal FS diet increased plasma glucose concentration significantly (P < 0·05) in females, but not in males. Post-weaning FS diet decreased glucose concentration significantly in females, but increased glucose concentration in males. There were no effects of the FS diet on phosphoenolpyruvate carboxykinase (PEPCK) mRNA expression in males, while the pattern of expression was related to plasma glucose concentration in females. The FS diet induced specific changes in the methylation of individual CpG in females, but not in males, which were related to the time of exposure. Methylation of CpG - 248 increased the binding of CCAAT-enhancer-binding protein β to the PEPCK promoter. Together, these findings show that both the period during the life course and sex influence the effect of increased exposure to folic acid on the epigenetic regulation of PEPCK and glucose homeostasis.

Folic acid and protein content in maternal diet and postnatal high-fat feeding affect the tissue levels of iron, zinc, and copper in the rat

Although maternal, fetal, and placental mechanisms compensate for disturbances in the fetal environment, any nutritional inadequacies present during pregnancy may affect fetal metabolism, and their consequences may appear in later life. The aim of the present study is to investigate the influence of maternal diet during gestation on Fe, Zn, and Cu levels in the livers and kidneys of adult rats. The study was carried out on the offspring (n = 48) of mothers fed either a protein-balanced or a protein-restricted diet (18% vs. 9% casein) during pregnancy, with or without folic acid supplementation (0.005- vs. 0.002-g folic acid/kg diet). At 10 weeks of age, the offspring of each maternal group were randomly assigned to groups fed either the AIN-93G diet or a high-fat diet for 6 weeks, until the end of the experiment. The levels of Fe, Zn, and Cu in the livers and kidneys were determined by the F-AAS method. It was found that postnatal exposure to the high-fat diet was associated with increased hepatic Fe levels (p < 0.001), and with decreased liver Zn and Cu contents (p < 0.01 and p < 0.05, respectively), as well as with decreased renal Cu contents (p < 0.001). Moreover, the offspring's tissue mineral levels were also affected by protein and folic acid content in the maternal diet. Both prenatal protein restriction and folic acid supplementation increased the liver Zn content (p < 0.05) and the kidney Zn content (p < 0.001; p < 0.05, respectively), while folic acid supplementation resulted in a reduction in renal Cu level (p < 0.05). Summarizing, the results of this study show that maternal dietary folic acid and protein intake during pregnancy, as well as the type of postweaning diet, affect Fe, Zn, and Cu levels in the offspring of the rat. However, the mechanisms responsible for this phenomenon are unclear, and warrant further investigation.

Progressive, transgenerational changes in offspring phenotype and epigenotype following nutritional transition

Induction of altered phenotypes during development in response to environmental input involves epigenetic changes. Phenotypic traits can be passed between generations by a variety of mechanisms, including direct transmission of epigenetic states or by induction of epigenetic marks de novo in each generation. To distinguish between these possibilities we measured epigenetic marks over four generations in rats exposed to a sustained environmental challenge. Dietary energy was increased by 25% at conception in F0 female rats and maintained at this level to generation F3. F0 dams showed higher pregnancy weight gain, but lower weight gain and food intake during lactation than F1 and F2 dams. On gestational day 8, fasting plasma glucose concentration was higher and β-hydroxybutyrate lower in F0 and F1 dams than F2 dams. This was accompanied by decreased phosphoenolpyruvate carboxykinase (PEPCK) and increased PPARα and carnitine palmitoyl transferase-1 mRNA expression. PEPCK mRNA expression was inversely related to the methylation of specific CpG dinucleotides in its promoter. DNA methyltransferase (Dnmt) 3a2, but not Dnmt1 or Dnmt3b, expression increased and methylation of its promoter decreased from F1 to F3 generations. These data suggest that the regulation of energy metabolism during pregnancy and lactation within a generation is influenced by the maternal phenotype in the preceding generation and the environment during the current pregnancy. The transgenerational effects on phenotype were associated with altered DNA methylation of specific genes in a manner consistent with induction de novo of epigenetic marks in each generation.

Protein and folic acid content in the maternal diet determine lipid metabolism and response to high-fat feeding in rat progeny in an age-dependent manner

Maternal diet during gestation can exert a long-term effect on the progeny's health by programming their developmental scheme and metabolism. The aim of this study is to analyze the influence of maternal diet on lipid metabolism in 10- and 16-week-old rats. Pregnant dams were fed one of four diets: a normal protein and normal folic acid diet (NP-NF), a protein-restricted and normal folic acid diet (PR-NF), a protein-restricted and folic-acid-supplemented diet (PR-FS), or a normal protein and folic-acid-supplemented diet (NP-FS). We also tested whether prenatal nutrition determines the reaction of an organism to a postweaning high-fat diet. Blood biochemistry and biometrical parameters were evaluated. The expression patterns of PPARα, PPARγ, and LXRα in the liver and adipose tissue were examined by real-time PCR. In the 10-week-old, rats folic acid supplementation of the maternal diet was associated with reduced circulating glucose and total cholesterol concentrations (P < 0.01 and P < 0.001, respectively). Neither prenatal diets nor postnatal feeding affected blood insulin concentrations. In the 16-week-old rats, body weight, abdominal fat mass and central adiposity were reduced in the progeny of the folic acid-supplemented dams (P < 0.01, P < 0.001 and P < 0.01, respectively). Maternal protein restriction had no effect on biometry or blood biochemical parameters. Folic acid supplementation of the maternal diet was associated with reduced expression of PPARα, PPARγ, and LXRα in the liver (P < 0.001). Reduced protein content in the maternal diet was associated with increased PPARα mRNA level in the liver (P < 0.001) and reduced LXRα in adipose tissue (P < 0.01). PPARα and PPARγ transcription in the liver, as well as LXRα transcription in adipose tissue, was also dependent on interaction effects between prenatal and postnatal diet compositions. PPARγ transcription in the liver was correlated with the abdominal fat mass, body weight, and calorie intake, while PPARγ transcription in adipose tissue was correlated with reduced body weight and calorie intake. Total serum cholesterol concentration was correlated with LXRα transcription in the liver. Folic acid supplementation of the maternal diet may have favorable effects for lipid metabolism in the progeny, but these effects are modified by the postnatal diet and age. Furthermore, the expression of LXRα, PPARα, and PPARγ in the liver and adipose tissue largely depends on the protein and folic acid content in the maternal diet during gestation. However, the altered transcription profile of these key regulators of lipid metabolism does not straightforwardly explain the observed phenotype.

Developmental programming of the metabolic syndrome - critical windows for intervention

Metabolic disease results from a complex interaction of many factors, including genetic, physiological, behavioral and environmental influences. The recent rate at which these diseases have increased suggests that environmental and behavioral influences, rather than genetic causes, are fuelling the present epidemic. In this context, the developmental origins of health and disease hypothesis has highlighted the link between the periconceptual, fetal and early infant phases of life and the subsequent development of adult obesity and the metabolic syndrome. Although the mechanisms are yet to be fully elucidated, this programming was generally considered an irreversible change in developmental trajectory. Recent work in animal models suggests that developmental programming of metabolic disorders is potentially reversible by nutritional or targeted therapeutic interventions during the period of developmental plasticity. This review will discuss critical windows of developmental plasticity and possible avenues to ameliorate the development of postnatal metabolic disorders following an adverse early life environment.

The richness of social stimuli shapes developmental trajectories: Are laboratory mouse pups impoverished?

The early environment is crucial for brain and behavior development. In particular, social experiences involving the mother and the peers are critical in shaping the adult individual. Though animal models of psychiatric disorders have widely investigated the relevance of the mother-offspring interaction, the peer interaction has so far been rarely studied. The communal nest (CN) is an innovative experimental strategy that favors a more comprehensive investigation of the long-term effects of both components. CN is a rearing condition employed by up to 90% of mouse females in naturalistic settings and consists of a single nest where two or more mothers keep their pups together and share care-giving. In a CN, the developing pup is exposed to high levels of both maternal care and interaction with peers. At adulthood, these mice display relevant changes in bran function and behavior, including high levels of neural plasticity markers, such as BDNF, and elaborate adult social competences. Overall, on the one hand, CN is an experimental approach complementary to the ones currently used that allows to investigate how the early environment determines developmental trajectories. On the other, it may represent a strategy to improve the study of animal models of psychiatric disorders characterized by social dysfunction, such as major depression, autism and attention deficit hyperactivity disorder. Indeed, the more elaborate social competences shown by these mice at adulthood may allow to better characterize deficits in the social domain induced by genetic and/or environmental manipulations.

Maternal protein and folic acid intake during gestation does not program leptin transcription or serum concentration in rat progeny

Maternal nutrition during gestation influences the development of the fetus, thereby determining its phenotype, including nutrient metabolism, appetite, and feeding behavior. The control of appetite is a very complex process and can be modulated by orexigenic and anorexigenic mediators such as leptin, which is involved in the regulation of energy homeostasis by controlling food intake and energy expenditure. Leptin transcription and secretion are regulated by numerous factors, nutrition being one of them. The present study was designed to test whether maternal nutrition can permanently affect leptin gene transcription and leptin serum concentration in rat progeny. Moreover, we analyzed whether leptin expression and secretion in response to high-fat postweaning feeding depends on the maternal diet during gestation. Pregnant rats were fed either a normal protein, normal folic acid diet (the AIN-93 diet); a protein-restricted, normal folic acid diet; a protein-restricted, folic acid-supplemented diet; or a normal protein, folic acid-supplemented diet. After weaning, the progeny was fed either the AIN-93 diet or a high-fat diet. Neither maternal nutrition nor the postweaning diet significantly affected Lep transcription. High-fat feeding after weaning was associated with higher serum leptin concentration, but the reaction of an organism to the fat content of the diet was not determined by maternal nutrition during gestation. There was no correlation between Lep mRNA level and serum leptin concentration. Global DNA methylation in adipose tissue was about 30% higher in rats fed postnatally the high-fat diet (P < 0.01). Our study showed that the protein and folic acid content in the maternal diet had no significant programming effect on Lep transcription and serum leptin concentration in the rats.

Dietary protein restriction during F0 pregnancy in rats induces transgenerational changes in the hepatic transcriptome in female offspring

There is considerable evidence for non-genomic transmission between generations of phenotypes induced by environmental exposures during development, although the mechanism is poorly understood. We investigated whether alterations in expression of the liver transcriptome induced in F1 offspring by feeding F0 dams a protein-restricted (PR) diet during pregnancy were passed with or without further change to two subsequent generations. The number of genes that differed between adult female offspring of F0 protein-restricted (PR) and protein-sufficient (PS) dams was F1 1,684 genes, F2 1,680 and F3 2,062. 63/113 genes that were altered in all three generations showed directionally opposite differences between generations. There was a trend toward increased proportions of up-regulated genes in F3 compared to F1. KEGG analysis showed that only the Adherens Junctions pathway was altered in all three generations. PR offspring showed altered fasting glucose homeostasis and changes in phosphoenolpyruvate carboxykinase promoter methylation and expression in all three generations. These findings show that dietary challenge during F0 pregnancy induced altered gene expression in all three generations, but relatively few genes showed transmission of altered expression between generations. For the majority of altered genes, these changes were not found in all generations, including some genes that were changed in F3 but not F1, or the direction and magnitude of difference between PR and PS differed between generations. Such variation may reflect differences between generations in the signals received by the fetus from the mother as a consequence of changes in the interaction between her phenotype and the environment.

Epigenetics in women's health care

Epigenetics refers to structural modifications to genes that do not change the nucleotide sequence itself but instead control and regulate gene expression. DNA methylation, histone modification, and RNA regulation are some of the mechanisms involved in epigenetic modification. Epigenetic changes are believed to be a result of changes in an organism's environment that result in fixed and permanent changes in most differentiated cells. Some environmental changes that have been linked to epigenetic changes include starvation, folic acid, and various chemical exposures. There are periods in an organism's life cycle in which the organism is particularly susceptible to epigenetic influences; these include fertilization, gametogenesis, and early embryo development. These are also windows of opportunity for interventions during the reproductive life cycle of women to improve maternal-child health. New data suggest that epigenetic influences might be involved in the regulation of fetal development and the pathophysiology of adult diseases such as cancer, diabetes, obesity, and neurodevelopmental disorders. Various epigenetic mechanisms may also be involved in the pathogenesis of preeclampsia and intrauterine growth restriction. Additionally, environmental exposures are being held responsible for causing epigenetic changes that lead to a disease process. Exposure to heavy metals, bioflavonoids, and endocrine disruptors, such as bisphenol A and phthalates, has been shown to affect the epigenetic memory of an organism. Their long-term effects are unclear at this point, but many ongoing studies are attempting to elucidate the pathophysiological effects of such gene-environment interactions.

Child health, developmental plasticity, and epigenetic programming

Plasticity in developmental programming has evolved in order to provide the best chances of survival and reproductive success to the organism under changing environments. Environmental conditions that are experienced in early life can profoundly influence human biology and long-term health. Developmental origins of health and disease and life-history transitions are purported to use placental, nutritional, and endocrine cues for setting long-term biological, mental, and behavioral strategies in response to local ecological and/or social conditions. The window of developmental plasticity extends from preconception to early childhood and involves epigenetic responses to environmental changes, which exert their effects during life-history phase transitions. These epigenetic responses influence development, cell- and tissue-specific gene expression, and sexual dimorphism, and, in exceptional cases, could be transmitted transgenerationally. Translational epigenetic research in child health is a reiterative process that ranges from research in the basic sciences, preclinical research, and pediatric clinical research. Identifying the epigenetic consequences of fetal programming creates potential applications in clinical practice: the development of epigenetic biomarkers for early diagnosis of disease, the ability to identify susceptible individuals at risk for adult diseases, and the development of novel preventive and curative measures that are based on diet and/or novel epigenetic drugs.

Effect of maternal diet on the epigenome: implications for human metabolic disease

The rapid increase in the incidence of chronic non-communicable diseases over the past two decades cannot be explained solely by genetic and adult lifestyle factors. There is now considerable evidence that the fetal and early postnatal environment also strongly influences the risk of developing such diseases in later life. Human studies have shown that low birth weight is associated with an increased risk of CVD, type II diabetes, obesity and hypertension, although recent studies have shown that over-nutrition in early life can also increase susceptibility to future metabolic disease. These findings have been replicated in a variety of animal models, which have shown that both maternal under- and over-nutrition can induce persistent changes in gene expression and metabolism within the offspring. The mechanism by which the maternal nutritional environment induces such changes is beginning to be understood and involves the altered epigenetic regulation of specific genes. The demonstration of a role for altered epigenetic regulation of genes in the developmental induction of chronic diseases raises the possibility that nutritional or pharmaceutical interventions may be used to modify long-term cardio-metabolic disease risk and combat this rapid rise in chronic non-communicable diseases.

Developmental plasticity and developmental origins of non-communicable disease: theoretical considerations and epigenetic mechanisms

There is now evidence that developmental influences have lifelong effects on cardiovascular and metabolic function and that elements of the heritable or familial component of susceptibility to cardiovascular disease, obesity and other non-communicable diseases (NCD) can be transmitted across generations by non-genomic means. In animals the developmental environment induces altered phenotypes through genetic, physiological (especially endocrine) and epigenetic mechanisms. The latter include DNA methylation, covalent modifications of histones and non-coding RNAs. Such 'tuning' of phenotype has potential adaptive value and may confer Darwinian fitness advantage because it either adjusts the phenotype to current circumstances and/or attempts to match an individual's responses to the environment predicted to be experienced later. When the phenotype is mismatched to the later environment, e.g. from inaccurate nutritional cues from the mother or placenta before birth, or from rapid environmental change through improved socio-economic conditions, risk of NCD increases. Such mechanisms are also thought to play roles in ageing and early onset of puberty, reinforcing a life-course perspective on such adaptive responses, especially the detrimental later effects of trade-offs. Epigenetic changes induced during development are highly gene-specific and function at the level of individual CpG dinucleotides in both gene promoter and intergenic regions. Evidence is accruing that endocrine or nutritional interventions during early postnatal life can reverse epigenetic and phenotypic changes induced, for example, by unbalanced maternal diet during pregnancy. Elucidation of epigenetic processes may permit perinatal identification of individuals most at risk of later NCD and enable early intervention strategies to reduce such risk.