Metabolic Phenotype Of Offspring Research Articles

The adverse effects of vitrification on mouse embryo development and metabolic phenotype in offspring.

Embryo vitrification is a standard procedure in assisted reproductive technology. Previous studies have shown that frozen embryo transfer is associated with an elevated risk of adverse maternal and neonatal outcomes. This study aimed to explore the effects of mouse blastocyst vitrification on the phenotype of vitrified-warmed blastocysts, their intrauterine and postnatal development, and the long-term metabolic health of the derived offspring. The vitrified-warmed blastocysts (IVF + VT group) exhibited reduced mitochondrial activity, increased apoptotic levels, and decreased cell numbers when compared to the fresh blastocysts (IVF group). Implantation rates, live pup rates, and crown-rump length at E18.5 were not different between the two groups. However, there was a significant decrease in fetal weight and fetal/placental weight ratio in the IVF + VT group. Furthermore, the offspring of the IVF + VT group at an age of 36 weeks had reduced whole energy consumption, impaired glucose and lipid metabolism when compared with the IVF group. Notably, RNA-seq results unveiled disturbed hepatic gene expression in the offspring from vitrified-warmed blastocysts. This study revealed the short-term negative impacts of vitrification on embryo and fetal development and the long-term influence on glucose and lipid metabolism that persist from the prenatal stage into adulthood in mice.

Preconceptional exposure of adult male rats to bisphenol S impairs insulin sensitivity and glucose tolerance in their male offspring

Since the use of bisphenol A (BPA) has been restricted because of its endocrine disruptor properties, bisphenol S (BPS) has been widely used as a substitute of BPA. However, BPS exerts similar effects on metabolic health as BPA. The effects of maternal exposure to BPA and BPS on the metabolic health of offspring have been largely documented during the past decade. However, the impact of preconceptional paternal exposure to BPS on progenies remains unexplored. In this study we investigated the impact of paternal exposure to BPS before conception, on the metabolic phenotype of offspring. Male Wistar rats were administered BPS through drinking water at the dose of 4 μg/kg/day (BPS-4 sires) or 40 μg/kg/day (BPS-40 sires) for 2 months before mating with females. The progenies (F1) were studied at fetal stage and in adulthood. We showed that preconceptional paternal exposure to BPS for 2 months did not alter the metabolic status of sires. The female offspring of sires exposed to lower or higher doses of BPS showed no alteration of their metabolic phenotype compared to females from control sires. In contrast, male offspring of BPS-4 sires exhibited increased body weight and body fat/lean ratio, decreased insulin sensitivity and increased glucose-induced insulin secretion at adult age, compared to the male offspring of control sires. Moreover, male offspring of BPS-4 sires developed glucose intolerance later in life. None of these effects were apparent in male offspring of BPS-40 sires. In conclusion, our study provides the first evidence of the non-monotonic and sex-specific effects of preconceptional paternal exposure to BPS on the metabolic health of offspring, suggesting that BPS is not a safe BPA substitute regarding the inter-generational transmission of metabolic disorders through the paternal lineage.

Developmental programming: Preconceptional and gestational exposure of sheep to a real-life environmental chemical mixture alters maternal metabolome in a fetal sex-specific manner

BackgroundEveryday, humans are exposed to a mixture of environmental chemicals some of which have endocrine and/or metabolism disrupting actions which may contribute to non-communicable diseases. The adverse health impacts of real-world chemical exposure, characterized by chronic low doses of a mixture of chemicals, are only recently emerging. Biosolids derived from human waste represent the environmental chemical mixtures humans are exposed to in real life. Prior studies in sheep have shown aberrant reproductive and metabolic phenotypes in offspring after maternal biosolids exposure. ObjectiveTo determine if exposure to biosolids perturbs the maternal metabolic milieu of pregnant ewes, in a fetal sex-specific manner. MethodsEwes were grazed on inorganic fertilizer (Control) or biosolids-treated pastures (BTP) from before mating and throughout gestation. Plasma from pregnant ewes (Control n = 15, BTP n = 15) obtained mid-gestation were analyzed by untargeted metabolomics. Metabolites were identified using Agilent MassHunter. Multivariate analyses were done using MetaboAnalyst 5.0 and confirmed using SIMCA. ResultsUnivariate and multivariate analysis of 2301 annotated metabolites identified 193 differentially abundant metabolites (DM) between control and BTP sheep. The DM primarily belonged to the super-class of lipids and organic acids. 15-HeTrE, oleamide, methionine, CAR(3:0(OH)) and pyroglutamic acid were the top DM and have been implicated in the regulation of fetal growth and development. Fetal sex further exacerbated differences in metabolite profiles in the BTP group. The organic acids class of metabolites was abundant in animals with male fetuses. Prenol lipid, sphingolipid, glycerolipid, alkaloid, polyketide and benzenoid classes showed fetal sex-specific responses to biosolids. DiscussionOur study illustrates that exposure to biosolids significantly alters the maternal metabolome in a fetal sex-specific manner. The altered metabolite profile indicates perturbations to fatty acid, arginine, branched chain amino acid and one‑carbon metabolism. These factors are consistent with, and likely contribute to, the adverse phenotypic outcomes reported in the offspring.

Small Noncoding RNAs Contribute to Sperm Oxidative Stress-Induced Programming of Behavioral and Metabolic Phenotypes in Offspring.

There is growing evidence that paternal environmental information alters small noncoding RNAs (sncRNAs) in sperm and in turn can induce alterations of metabolic and behavioral phenotypes of the next generation. However, the potential mediators of the effects remain to be elucidated. A great diversity of environmental insults and stresses can convergently induce the elevation of reactive oxygen species (ROS) in sperm; nonetheless, it remains unclear whether ROS mediates the biogenesis of sncRNAs in sperm and participates in the reprogramming of offspring phenotypes. Here, we show that ROS could induce the alteration of sncRNA profiles in sperm, especially for transfer RNA-derived small RNAs (tsRNAs) and ribosomal RNA-derived small RNAs (rsRNAs). Zygotic injection of 29-34 nt RNA fractions (predominantly tsRNAs and rsRNAs) from oxidative stress (OS) sperm could induce depressive-like and anxiety-like behaviors in male offspring. Moreover, zygotic injection with synthetic RNAs partially resembled OS sperm-induced depressive-like and anxiety-like behaviors in offspring. Male offspring maintained on a chow diet was found to develop impaired glucose tolerance and hyperactive hepatic gluconeogenesis, accompanied by the upregulation of hepatic gluconeogenic and lipolytic genes. Together, our results have shown that ROS-induced alteration of sncRNA profiles in sperm contributes to the alterations of behavioral and metabolic phenotypes of the offspring.

Vitamin D Deficiency During Development Permanently Alters Liver Cell Composition and Function.

Vitamin D, a fat-soluble vitamin, plays a critical role in calcium homeostasis, the immune system, and normal development. Many epidemiological cohort studies globally have found high prevalence rates of vitamin D deficiency and insufficiency, recognized as an important health issue that needs to be solved. In particular, reproductive age and pregnant women low in vitamin D status may confer risks of diseases like obesity on their offspring. While observational studies have suggested associations between prenatal vitamin D deficiency and metabolic phenotypes in offspring, not yet determined is whether prenatal vitamin D deficiency permanently alters the development of the liver, a major metabolic organ. We tested the histopathology and the transcriptomic profiles of livers from male C57BL/6J mice exposed to prenatal vitamin D deficiency through a maternal dietary intervention model. We found that prenatal vitamin D deficiency increases the prevalence of histopathological changes in the liver, and alters its gene expression profile. Cell subtype proportion analysis showed that the liver of prenatal vitamin D deficiency alters non-parenchymal cells of the liver, specifically macrophages, a subset of endothelial cells, and dendritic cells. Our results indicate the long-term memory of prenatal vitamin D deficiency exposure in the adult liver, a potential contributor to offspring health risks.

Paternal High-Protein Diet Programs Offspring Insulin Sensitivity in a Sex-Specific Manner

The impact of maternal nutrition on offspring is well documented. However, the implication of pre-conceptional paternal nutrition on the metabolic health of the progeny remains underexplored. Here, we investigated the impact of paternal high-protein diet (HPD, 43.2% protein) consumption on the endocrine pancreas and the metabolic phenotype of offspring. Male Wistar rats were given HPD or standard diet (SD, 18.9% protein) for two months. The progenies (F1) were studied at fetal stage and in adulthood. Body weight, glycemia, glucose tolerance (GT), glucose-induced insulin secretion in vivo (GIIS) and whole-body insulin sensitivity were assessed in male and female F1 offspring. Insulin sensitivity, GT and GIIS were similar between F1 females from HPD (HPD/F1) and SD fathers (SD/F1). Conversely, male HPD/F1 exhibited increased insulin sensitivity (p < 0.05) and decreased GIIS (p < 0.05) compared to male SD/F1. The improvement of insulin sensitivity in HPD/F1 was sustained even after 2 months of high-fat feeding. In male HPD/F1, the β cell mass was preserved and the β cell plasticity, following metabolic challenge, was enhanced compared to SD/F1. In conclusion, we provide the first evidence of a sex-specific impact of paternal HPD on the insulin sensitivity and GIIS of their descendants, demonstrating that changes in paternal nutrition alter the metabolic status of their progeny in adulthood.

Prenatal Exposure to Persistent Organic Pollutants and Maternal Folic Acid Supplementation: Their Impact on Glucose Homeostasis in Male Rat Descendants

Exposure to persistent organic pollutants (POPs) is associated with insulin resistance while folic acid (FA) may offer a protective effect. However, the paternal contribution to metabolic phenotypes in offspring is not well known yet. Hence, we investigated whether maternal exposure to POPs affects glucose homeostasis and whether maternal FA supplementation counteracts POP effects transmitted via male descendants. Sprague–Dawley founder dams (F0) were fed a diet containing 2 or 6 mg/kg of FA and were force-fed with either a POP mixture or corn oil for 9 weeks. Subsequent male descendants did not receive any treatment. Blood glucose, plasma insulin and C-peptide were measured during an oral glucose tolerance test in males aged 90 and 180 days from generation 1 (F1), 2 (F2) and 3 (F3). Prenatal POP exposure increased fasting glucose in 90-day-old F1 males and C-peptide in 90-day-old F2 males. Prenatal FA supplementation decreased C-peptide in 90 and 180-day-old F1 males. In 180-day-old F3 males, FA supplementation counteracted POPs on fasting and postglucose C-peptide, indicating reduced insulin secretion. Prenatal exposure to an environmentally relevant POP mixture caused abnormalities in glucose homeostasis that are transmitted from one generation to the next through the paternal lineage. Prenatal FA supplementation counteracted some of the deleterious effects of POPs on glucose homeostasis.

700-P: Mechanism for the Beneficial Effects of Maternal Exercise to Improve Offspring Metabolic Health

Poor maternal diet and obesity increase the risk of obesity and type 2 diabetes in offspring, fueling the worldwide epidemic of these diseases. Recent animal studies have shown that maternal exercise (MatEx) improves the metabolic phenotype of offspring in adulthood, including improved glucose tolerance and liver function. Here, we determined the molecular mechanisms responsible for these critical effects of MatEx. Female mice were fed a chow or high fat diet and housed in cages with (Trained) or without (Sedentary) running wheels for 2 wks prior to breeding and during gestation. Offspring were sedentary and chow-fed. MatEx improved glucose tolerance and liver function in adult offspring. Beginning at embryonic day 13.5, MatEx increased expression of TCA cycle and fatty acid oxidation genes in offspring liver, and increased DNA demethylation at promoters of these hepatic genes. Next, we identified a novel MatEx-induced AMPK/isocitrate dehydrogenase/αketoglutarate/Tet axis in offspring liver controlling DNA demethylation. Primary hepatoblasts treated with serum from trained dams, but not sedentary dams or trained non-pregnant females stimulated this pathway, suggesting the effects of MatEx on offspring stem from a placenta-derived serum factor(s). LC-MS/MS of serum and RNAseq of placenta from trained dams identified this factor as superoxide dismutase 3 (Sod3), and recombinant SOD3 treatment of hepatoblasts increased AMPK-Tet signaling and hepatic gene expression. The effects of MatEx to increase liver AMPK-Tet signal, alter liver DNA methylation and gene expression, and improve offspring glucose tolerance in vivo were ablated in placenta-specific Sod3 KO mice. Finally, SOD3 was increased in serum and placenta from highly physically active pregnant women. Sod3 is an exercise-induced, placenta-derived protein that improves glucose homeostasis via epigenetic changes in offspring liver, defining a novel paradigm for the beneficial effects of exercise on metabolic health. Disclosure J. Kusuyama: None. A.B. Wagner: None. R.H. Conlin: None. N.S. Makarewicz: None. M. Møller: None. E.M. Miele: None. R. Middelbeek: None. N. Jessen: None. P.G. Ovesen: None. M.F. Hirshman: Stock/Shareholder; Self; Abbott Laboratories, AbbVie Inc., Amgen, Colgate-Palmolive, Eli Lilly and Company, Medtronic. K.B. Adamo: None. E.N. Grayck: None. L.J. Goodyear: None. Funding National Institutes of Health (DK101043)

Diet during Pregnancy is Implicated in the Regulation of Hypothalamic RNA Methylation and Risk of Obesity in Offspring.

Early life nutrition has long-lasting influence in adults through key mediators that modulate epigenetic states, although the determinants involved that underlie this response remain controversial. Because of the similarities between metabolic, physiological, and endocrine changes and those occurring in human type 2 diabetes, we studied the interaction of diet during pregnancy regulating RNA adenosine methylation (N6-methyladenosine [m6A]) and the transcriptome in Psammomys obesus. Breeding pairs were randomly allocated standard diet (total digestible energy 18MJkg-1 ) or low-fat diet (15MJkg-1 ). Offspring were weaned onto the low-fat diet at 4 weeks of age and given ad libitum access, resulting in two experimental groups: 1) male offspring of animals fed a low-fat diet and weaned onto the low-fat diet and 2) male offspring of animals fed a standard diet and weaned onto the low-fat diet. Hypothalamic RNA was used to assess m6A by immunoprecipitation. Parental low-fat diet alters the metabolic phenotype in offspring. An association between parental diet and hypothalamic m6A was observed in regulating the expression of FTO and METTL3 in the offspring. We propose the regulatory capacity is now broadened for the first time to include m6A in developmental programming and obesity phenotype.

Prenatal arsenic exposure and dietary folate and methylcobalamin supplementation alter the metabolic phenotype of C57BL/6J mice in a sex-specific manner.

Inorganic arsenic (iAs) is an established environmental diabetogen. The link between iAs exposure and diabetes is supported by evidence from adult human cohorts and adult laboratory animals. The contribution of prenatal iAs exposure to the development of diabetes and underlying mechanisms are understudied. The role of factors that modulate iAs metabolism and toxicity in adults and their potential to influence diabetogenic effects of prenatal iAs exposure are also unclear. The goal of this study was to determine if prenatal exposure to iAs impairs glucose metabolism in mice and if maternal supplementation with folate and methylcobalamin (B12) can modify this outcome. C57BL/6J dams were exposed to iAs in drinking water (0, 100, and 1000µg As/L) and fed a folate/B12 adequate or supplemented diet from before mating to birth of offspring. After birth, dams and offspring drank deionized water and were fed the folate/B12 adequate diet. The metabolic phenotype of offspring was assessed over the course of 14 weeks. Male offspring from iAs-exposed dams fed the folate/B12-adequate diet developed fasting hyperglycemia and insulin resistance. Maternal folate/B12 supplementation rescued this phenotype but had only marginal effects on iAs metabolism in dams. The diabetogenic effects of prenatal iAs exposure in male offspring were not associated with changes in global DNA methylation in the liver. Only minimal effects of prenatal iAs exposure or maternal supplementation were observed in female offspring. These results suggest that prenatal iAs exposure impairs glucose metabolism in a sex-specific manner and that maternal folate/B12 supplementation may improve the metabolic phenotype in offspring. Further studies are needed to identify the mechanisms underlying these effects.

Diet-induced obesity leads to metabolic dysregulation in offspring via endoplasmic reticulum stress in a sex-specific manner.

Exposure to metabolic stress has been suggested to influence the susceptibility to metabolic disorders in offspring according to epidemiological and animal studies. Nevertheless, molecular mechanisms remain unclear. We investigated impacts of diet-induced paternal obesity on metabolic phenotypes in offspring and its underlying molecular mechanism. Male founder mice (F0), fed with control diet (CD) or high-fat diet (HFD), were mated with CD-fed females. F1 progenies were mated with outbred mice to generate F2 mice. All offspring were maintained on CD. Metabolic phenotypes, metabolism-related gene expression and endoplasmic reticulum (ER) stress markers were measured in serum or relevant tissues of F2 mice. DNA methylation in sperm and testis of the founder and in the liver of F2 mice was investigated. Male founder obesity, instigated by HFD, led to glucose dysregulation transmitted down to F2. We found that F2 males to HFD founders were overweight and had a high fasting glucose relative to F2 to CD founders. F2 females to HFD founders, in contrast, had a reduced bodyweight relative to F2 to CD founders and exhibited an early onset of impaired glucose homeostasis. The sex-specific difference was associated with distinct transcriptional patterns in metabolism-related organs, showing altered hepatic glycolysis and decreased adipose Glucose transporter 4 (Glut4) in males and increased gluconeogenesis and lipid synthesis in females. Furthermore, the changes in females were linked to hepatic ER stress, leading to suppressed insulin signaling and non-obese hyperglycemic phenotypes. DNA methylation analysis revealed that the Nr1h3 locus was sensitive to HFD at founder germ cells and the alteration was also detected in the liver of F2 female. Our findings demonstrate that male founder obesity influences impaired glucose regulation in F2 progeny possibly via ER stress in a sex-specific manner and it is, in part, contributed by altered DNA methylation at the Nr1h3 locus.

Paternal hyperglycemia in rats exacerbates the development of obesity in offspring.

Parental history with obesity or diabetes will increase the risk for developing metabolic diseases in offspring. However, literatures as to transgenerational inheritance of metabolic dysfunctions through male lineage are relatively scarce. In the current study, we aimed to evaluate influences of paternal hyperglycemia on metabolic phenotypes in offspring. Male SD rats were i.p. injected with streptozotocin (STZ) or citrate buffer (CB, as control). STZ-injected rats with glucose levels higher than 16.7 mM were selected to breed with normal female rats. Offspring from STZ or CB treated fathers (STZ-O and CB-O) were maintained in the identical condition. We monitored body weight and food intake, and tests of glucose and insulin tolerance (GTTs and ITTs), fasting-refeeding and cold exposure were performed. Expression of factors involved in hypothalamic feeding and brown adipose tissue (BAT) thermogenic activity was performed by real-time PCR and Western blot. Adult STZ-O were heavier than CB-O. Impairment of GTTs was observed in STZ-O compared with CB-O at 22 and 32 weeks of age; ITTs results showed decreased insulin sensitivity in STZ-O. Daily food intake and accumulated food intake during 12-h refeeding after fasting were significantly higher in STZ-O. UCP1 levels were downregulated in BAT from STZ-O at room temperature and cold exposure. Finally, STZ-O rats showed suppressed leptin signaling in the hypothalamus as evidenced by upregulated SOCS3, reduced phosphorylation of STAT3, impaired processing POMC and decreased α-MSH production. Our study revealed that paternal hyperglycemia predisposes offspring to developing obesity, which is possibly associated with impaired hypothalamic leptin signaling.

Lipid overload during gestation and lactation can independently alter lipid homeostasis in offspring and promote metabolic impairment after new challenge to high-fat diet

BackgroundNutritional status in early life is critically involved in the metabolic phenotype of offspring. However the changes triggered by maternal consumption of high-fat diet (HFD) in pre- or postnatal period should be better understood. Here we evaluated whether maternal HFD consumption during gestation and lactation could differently affect liver miR-122 and miR-370 expression leading to metabolic damages observed in offspring. Moreover, we investigate whether early overnutrition program offspring to more harmful response to HFD in later life.MethodsFemale mice were fed either a standard chow (SC) diet or a HFD three weeks before and during mating, gestation and/or lactation. Offspring were evaluated on the delivery day (d0), in a cross-fostering model at day 28 (d28) and in adult life, after a re-challenge with a HFD (d82).ResultsIn vitro analysis using liver cell line showed that palmitate could induced decrease in miR-122 and increase in miR-370 expression. Newborn pups (d0) from obese dams showed a decrease in lipid oxidation markers (Cpt1a and Acadvl), an increase in triacylglycerol synthesis markers (Agpat and Gpam), as well as lower miR-122 and higher miR-370 hepatic content that was inversely correlated to maternal serum NEFA and TAG. Pups fostered to SC dams presented an increase in body weight and Agpat/Gpam expression at d28 compared to pups fostered to HFD dams and an inverse correlation was observed between miR-122 hepatic expression and offspring serum TAG. In adult life (d82), the reintroduction of HFD resulted in higher body weight gain and hepatic lipid content. These effects were accompanied by impairment in lipid and glucose metabolism, demonstrated by reduced Cpt1a/Acadvl and increased Agpat/Gpam expression, lower glucose tolerance and insulin sensitivity.ConclusionOur data suggest that both gestational and lactation overnutrition results in metabolic changes that can permanently alter lipid homeostasis in offspring. The presence of fatty acids in maternal blood and milk seem to be responsible for modulating the expression of miR-122 and miR-370, which are involved in liver metabolism. These alterations significantly increase susceptibility to obesity and ectopic lipid accumulation and lead to a more harmful response to HFD in offspring.

Integrated stress response activation by sleep fragmentation during late gestation in mice leads to emergence of adverse metabolic phenotype in offspring

BackgroundLate gestational sleep fragmentation (SF) is highly prevalent particularly in obese women, and induces metabolic dysfunction in adult offspring mice. SF induces activation of the integrated stress response (ISR), which might be involved in metabolic disorders. We hypothesized that adult offspring of double mutant mice (DM) involving the critical ISR genes CHOP and GADD34 would be protected from developing obesity and insulin resistance following SF. MethodsTime-pregnant CHOP/GADD34 DM and wild type (WT) mice were randomly assigned to sleep control (SC) or SF conditions during the last 5days of gestation. At 24-weeks of age, body weight, fat mass, and HOMA-IR were assessed in the offspring. Tregs lymphocytes, Lyc6chigh, M1 and M2 macrophages were examined in visceral white adipose tissues (vWAT) using flow cytometry. The effects of plasma exosomes on adipocyte cell line proliferation, differentiation and insulin sensitivity were also evaluated. ResultsSF-WT male showed significant increases in body weight, vWAT mass and HOMA-IR compared to SC-WT mice, while SF had no effect in SF-DM mice. Inflammatory macrophages (Ly-6chigh) and the ratio of M1/M2 macrophages were increased while FoxP3+ Tregs counts were decreased in SF-WT but not in SF-DM mice. Exosomes from SF-WT, but not from the SF-DM offspring increased pre-adipocyte proliferation and differentiation, and decreased in vitro adipocyte insulin sensitivity. ConclusionActivation of the ISR during late gestation, as induced by late gestational SF, appears to underlie some of the transgenerational modifications in metabolic genes ultimately contributing to a metabolic syndrome phenotype in adult offspring.

Small RNAs in Sperm, Affected by Diet, Transmit Information to Offspring

A class of small RNAs derived from tRNAs has a distinct profile in mice fed unhealthy diets, suggests two new studies. These RNAs may be involved in the intergenerational inheritance of metabolic states. Studies in the last several years have suggested that fathers can pass down metabolic information to offspring. For instance, male mice fed either a low-protein or high-fat diet produce offspring with metabolic abnormalities. In flies and worms, piRNAs—typically 25 to 33 nucleotides in length— have been implicated in transgenerational inheritance. But whether small RNAs have a similar role in mammals has been unclear. Previous research found that a class of small RNAs is abundant in mouse sperm, tRNA-derived small RNAS (tsRNAS). tRNAs are derived mainly from the 5 ends of tRNAs and have been suggested to have regulatory roles in various cell types. The new findings suggest that tsRNA profiles are different in sperm from males subjected to either a low-protein or high-fat diet. In one study, Qi Zhou and colleagues [1] fed mice a high-fat diet and isolated small RNAs from their sperm including a 30to 40-nucleotide fraction that consisted predominantly of tsRNAs. Injection of this RNA fraction into normal zygotes resulted in altered expression of numerous genes, including those involved in metabolic pathways; this RNA fraction also affected the metabolic phenotype of F1 offspring. In a second study, Oliver Rando and colleagues [2] provide evidence that tsRNAs are delivered to sperm via epididymosomes: vesicles that fuse with sperm as they transit through the epididymis. A protein-restricted diet resulted in increased levels of glycine tsRNAs, which seem to have a regulatory role in the embryo—for instance, interfering with a glycine tsRNAaffected expression of a set of about 70 genes in embryonic stem cells. Curiously, these genes are highly expressed in the preimplantation embryos and are regulated by the same DNA element (the long terminal repeat of the murine endogenous retroelement, MERVL). Injection of a synthetic oligo of this tsRNA affected expression of a similar set of genes in the early embryo. Whether injection of this oligo affected the metabolic phenotype of the offspring was not tested. The findings suggest that diet can affect tsRNAs in sperm and that these tsRNAs may have a role in intergenerational inheritance. But other factors may also come into play; for instance, other molecules were also altered in the sperm from males fed unhealthy diets, such as the let-7 small regulatory RNA. Another recent study in humans has suggested the piRNA profiles and DNA methylation in sperm is affected by diet [3].

Genetic and Epigenetic Variation, but Not Diet, Shape the Sperm Methylome

Paternal diet can impact metabolic phenotypes in offspring, but mechanisms underlying such intergenerational information transfer remain obscure. Here, we interrogate cytosine methylation patterns in sperm obtained from mice consuming one of three diets, generating whole genome methylation maps for four pools of sperm samples and for 12 individual sperm samples, as well as 61 genome-scale methylation maps. We find that "epivariation," either stochastic or due to unknown demographic or environmental factors, was a far stronger contributor to the sperm methylome than was the diet consumed. Variation in cytosine methylation was particularly dramatic over tandem repeat families, including ribosomal DNA (rDNA) repeats, but rDNA methylation was strongly correlated with genetic variation in rDNA copy number and was not influenced by paternal diet. These results identify loci of genetic and epigenetic lability in the mammalian genome but argue against a direct role for sperm cytosine methylation in dietary reprogramming of offspring metabolism.

Liver DNA methylation analysis in adult female C57BL/6JxFVB mice following perinatal exposure to bisphenol A

Bisphenol A (BPA) is a compound released from plastics and other consumer products used in everyday life. BPA exposure early in fetal development is proposed to contribute to programming of chronic diseases like obesity and diabetes, by affecting DNA methylation levels. Previously, we showed that in utero and lactational exposure of C57BL/6JxFVB hybrid mice via maternal feed using a dose range of 0–3000μg/kg body weight/day resulted in a sex-dependent altered metabolic phenotype in offspring at 23 weeks of age. The most univocal effects were observed in females, with reduced body weights and related metabolic effects associated with perinatal BPA exposure. To identify whether the effects of BPA in females are associated with changes in DNA methylation, this was analyzed in liver, which is important in energy homeostasis. Measurement of global DNA methylation did not show any changes. Genome-wide DNA methylation analysis at specific CpG sites in control and 3000μg/kg body weight/day females with the digital restriction enzyme analysis of methylation (DREAM) assay revealed potential differences, that could, however, not be confirmed by bisulfite pyrosequencing. Overall, we demonstrated that the observed altered metabolic phenotype in female offspring after maternal exposure to BPA was not detectably associated with liver DNA methylation changes. Still, other tissues may be more informative.

Forgotten fluids of the reproductive tract

Forgotten fluids of the reproductive tract

Maternal tract factors contribute to paternal seminal fluid impact on metabolic phenotype in offspring

Paternal characteristics and exposures influence physiology and disease risks in progeny, but the mechanisms are mostly unknown. Seminal fluid, which affects female reproductive tract gene expression as well as sperm survival and integrity, provides one potential pathway. We evaluated in mice the consequences for offspring of ablating the plasma fraction of seminal fluid by surgical excision of the seminal vesicle gland. Conception was substantially impaired and, when pregnancy did occur, placental hypertrophy was evident in late gestation. After birth, the growth trajectory and metabolic parameters of progeny were altered, most profoundly in males, which exhibited obesity, distorted metabolic hormones, reduced glucose tolerance, and hypertension. Altered offspring phenotype was partly attributable to sperm damage and partly to an effect of seminal fluid deficiency on the female tract, because increased adiposity was also evident in adult male progeny when normal two-cell embryos were transferred to females mated with seminal vesicle-excised males. Moreover, embryos developed in female tracts not exposed to seminal plasma were abnormal from the early cleavage stages, but culture in vitro partly alleviated this. Absence of seminal plasma was accompanied by down-regulation of the embryotrophic factors Lif, Csf2, Il6, and Egf and up-regulation of the apoptosis-inducing factor Trail in the oviduct. These findings show that paternal seminal fluid composition affects the growth and health of male offspring, and reveal that its impact on the periconception environment involves not only sperm protection but also indirect effects on preimplantation embryos via oviduct expression of embryotrophic cytokines.

Maternal nutritional history modulates the hepatic IGF–IGFBP axis in adult male rat offspring

Alterations in early life nutrition lead to an increased risk of obesity and metabolic syndrome in offspring. We have shown that both relative maternal undernutrition (UN) and maternal obesity result in metabolic derangements in offspring, independent of the postnatal dietary environment. Since insulin-like growth factor binding protein 2 (IGFBP2) has been shown to be independently associated with obesity and diabetes risk, we examined the IGF-IGFBP axis in male rat offspring following either maternal UN or maternal obesity to explain possible common pathways in the development of metabolic disorders. Wistar rats were time-mated and fed either a control diet (CONT), 50 % of CONT (UN) or a high-fat (HF) diet throughout pregnancy. Male offspring were weaned onto a standard chow diet and blood and tissues were collected at postnatal day 160. Plasma and hepatic tissue samples were analysed for key players in the IGF-IGFBP system. Both maternal UN and HF resulted in increased fat mass, hyperinsulinemia, hyperleptinemia and altered blood lipid profiles in offspring compared to CONT. Circulating IGF-1 and IGFBP3 levels and hepatic mRNA expression of IGFBP1 and IGFBP2 were significantly decreased in UN and HF offspring compared to CONT. DNA methylation of the IGFBP2 promotor region was similar between maternal dietary groups. Although chaperone gene heat-shock protein 90 and hepatic IGFBP1 were significantly correlated in CONT offspring this effect was absent in both UN and HF offspring. In conclusion, this study is one of the first to directly compare two experimental models of developmental programming representing both ends of the maternal dietary spectrum. Our data suggest that two disparate nutritional models that elicit similar adverse metabolic phenotypes in offspring are characterised by common alterations in the IGF-IGFBP pathway.