Expression of the placental transcriptome in maternal nutrient reduction in baboons is dependent on fetal sex

Gender associations between phthalate exposure and biomarkers of oxidative stress: A prospective cohort study

Previous epidemiologic research has shown that phthalate exposure in pregnant women is related to adverse birth outcomes in a sex-specific manner. However, the biological mechanism of phthalate exposure that causes these birth outcomes remains poorly defined. In this research, we investigated the association between phthalate exposure and placental oxidative stress in a large population-based cohort study, aiming to initially explore the relationship between phthalate exposure and gene expression in placental oxidative stress in a sex-specific manner. Quantitative PCR was performed to measure the expression of placental inflammatory mRNAs (HO-1, HIF1α, and GRP78) in 2469 placentae. The multiple linear regression models were used to investigate the associations between mRNA and urinary phthalate monoesters. Phthalate metabolites monomethyl phthalate (MMP) and mono-n-butyl phthalate (MBP) were positively correlated with higher HIF1α expression in placentae of male fetuses (p < .05). Mono-benzyl phthalate (MBzP) increased the expression of HO-1, HIF1α, and GRP78 in placentae of male fetuses, and mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) up-regulated the expression of HIF1α and GRP78. Additionally, mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP) was negatively correlated with HO-1, HIF1α, and GRP78 in placentae of female fetuses. Maternal phthalate exposure was associated with oxidative stress variations in placental tissues. The associations were closer in the placentas of male fetuses than in that of female ones. The placenta oxidative stress is worth further investigation as a potential mediator of maternal exposure-induced disease risk in children.

Maternal nutrition during mid-pregnancy and children's body composition at 7 years of age in the SELMA study

Optimal nutrition during pregnancy is vital for both maternal and child health. Our objective was to explore if prenatal diet is associated with children's height and body fat. Nutrient intake was assessed through a FFQ from 808 pregnant women and summarised to a nutrition index, 'My Nutrition Index' (MNI). The association with children's height and body fat (bioimpedance) was assessed with linear regression models. Secondary analysis was performed with BMI, trunk fat and skinfolds. Overall, higher MNI score was associated with greater height (β = 0·47; (95 % CI 0·00, 0·94), among both sexes. Among boys, higher MNI was associated with 0·15 higher BMI z-scores, 0·12 body fat z-scores, 0·11 trunk fat z-scores, and larger triceps, and triceps + subscapular skinfolds (β = 0·05 and β = 0·06; on the log2 scale) (P-value < 0·05). Among girls, the opposite associations were found with 0·12 lower trunk fat z-scores, and smaller subscapular and suprailiac skinfolds (β = -0·07 and β = -0·10; on the log2 scale) (P-value < 0·05). For skinfold measures, this would represent a ± 1·0 millimetres difference. Unexpectedly, a prenatal diet in line with recommended nutrient intake was associated with higher measures of body fat for boys and opposite to girls at a pre-pubertal stage of development.

Sexual dimorphism in placental development and function: Comparative physiology with an emphasis on the pig

Across mammalian species, it has been demonstrated that sex influences birth weight, with males being heavier than females; a characteristic that can be observed from early gestation. Male piglets are more likely to be stillborn and have greater preweaning mortality than their female littermates, despite the additional maternal investment into male fetal growth. Given the conserved nature of the genome between the sexes, it is hypothesized that these developmental differences between males and females are most likely orchestrated by differential placental adaptation. This review summarizes the current understanding of fetal sex-specific differences in placental and endometrial structure and function, with an emphasis on pathways found to be differentially regulated in the pig including angiogenesis, apoptosis, and proliferation. Given the importance of piglet sex in agricultural enterprises, and the potential for skewed litter sex ratios, it is imperative to improve understanding of the relationship between fetal sex and molecular signaling in both the placenta and endometria across gestation.

Maternal obesity alters the placental transcriptome in a fetal sex-dependent manner

Infants born to obese mothers have an increased risk of developing obesity and metabolic diseases in childhood and adulthood. Although the molecular mechanisms linking maternal obesity during pregnancy to the development of metabolic diseases in offspring are poorly understood, evidence suggests that changes in the placental function may play a role. Using a mouse model of diet-induced obesity with fetal overgrowth, we performed RNA-seq analysis at embryonic day 18.5 to identify genes differentially expressed in the placentas of obese and normal-weight dams (controls). In male placentas, 511 genes were upregulated and 791 genes were downregulated in response to maternal obesity. In female placentas, 722 genes were downregulated and 474 genes were upregulated in response to maternal obesity. The top canonical pathway downregulated in maternal obesity in male placentas was oxidative phosphorylation. In contrast, sirtuin signaling, NF-kB signaling, phosphatidylinositol, and fatty acid degradation were upregulated. In female placentas, the top canonical pathways downregulated in maternal obesity were triacylglycerol biosynthesis, glycerophospholipid metabolism, and endocytosis. In contrast, bone morphogenetic protein, TNF, and MAPK signaling were upregulated in the female placentas of the obese group. In agreement with RNA-seq data, the expression of proteins associated with oxidative phosphorylation was downregulated in male but not female placentas of obese mice. Similarly, sex-specific changes in the protein expression of mitochondrial complexes were found in placentas collected from obese women delivering large-for-gestational-age (LGA) babies. In conclusion, maternal obesity with fetal overgrowth differentially regulates the placental transcriptome in male and female placentas, including genes involved in oxidative phosphorylation.

Impaired social cognition caused by perinatal protein malnutrition evokes neurodevelopmental disorder symptoms and is intergenerationally transmitted

Nutritional inadequacy before birth and during postnatal life can seriously interfere with brain development and lead to persistent deficits in learning and behavior. In this work, we asked if protein malnutrition affects domains of social cognition and if these phenotypes can be transmitted to the next generation. Female mice were fed with a normal or hypoproteic diet during pregnancy and lactation. After weaning, offspring were fed with a standard chow. Social interaction, social recognition memory, and dominance were evaluated in both sexes of F1 offspring and in the subsequent F2 generation. Glucose metabolism in the whole brain was analyzed through preclinical positron emission tomography. Genome-wide transcriptional analysis was performed in the medial prefrontal cortex followed by gene-ontology enrichment analysis. Compared with control animals, malnourished mice exhibited a deficit in social motivation and recognition memory and displayed a dominant phenotype. These altered behaviors, except for dominance, were transmitted to the next generation. Positron emission tomography analysis revealed lower glucose metabolism in the medial prefrontal cortex of F1 malnourished offspring. This brain region showed genome-wide transcriptional dysregulation, including 21 transcripts that overlapped with autism-associated genes. Our study cannot exclude that the lower maternal care provided by mothers exposed to a low-protein diet caused an additional impact on social cognition. Our results showed that maternal protein malnutrition dysregulates gene expression in the medial prefrontal cortex, promoting altered offspring behavior that was intergenerationally transmitted. These results support the hypothesis that early nutritional deficiency represents a risk factor for the emergence of symptoms associated with neurodevelopmental disorders.

The Placenta's Role in Sexually Dimorphic Fetal Growth Strategies

Fetal sex affects the risk of pregnancy complications and the long-term effects of prenatal environment on health. Some have hypothesized that growth strategies differ between the sexes, whereby males prioritize growth whereas females are more responsive to their environment. This review evaluates the role of the placenta in such strategies, focusing on (1) mechanisms underlying sexual dimorphism in gene expression, (2) the nature and extent of sexual dimorphism in placental gene expression, (3) sexually dimorphic responses to nutrient supply, and (4) sexual dimorphism in morphology and histopathology. The sex chromosomes contribute to sex differences in placental gene expression, and fetal hormones may play a role later in development. Sexually dimorphic placental gene expression may contribute to differences in the prevalence of complications such as preeclampsia, although this link is not clear. Placental responses to nutrient supply frequently show sexual dimorphism, but there is no consistent pattern where one sex is more responsive. There are sex differences in the prevalence of placental histopathologies, and placental changes in pregnancy complications, but also many similarities. Overall, no clear patterns support the hypothesis that females are more responsive to the maternal environment, or that males prioritize growth. While male fetuses are at greater risk of a variety of complications, total prenatal mortality is higher in females, such that males exposed to early insults may be more likely to survive and be observed in studies of adverse outcomes. Going forward, robust statistical approaches to test for sex-dependent effects must be more widely adopted to reduce the incidence of spurious results.

Effects of vitrification and the superovulated environment on placental function and fetal growth in an IVF mouse model

In studies of human IVF, as compared to frozen embryo transfer (ET), fresh ET is associated with smaller infants and higher risk of small for gestational age infants. Recent observations suggest that ET using vitrified embryos is associated with higher pregnancy and live birth rates compared to fresh ET, but increased rates of large for gestational age infants. The mechanisms underlying these associations are largely unknown, and available evidence suggests that the influence of IVF, vitrification and the superovulated (SO) uterine environment on placental function and fetal growth is complex. This warrants further investigation given the prevalent practice in human IVF of both fresh ET into a SO uterine environment, and vitrification with ET into a more physiologic uterine environment. Using a mouse model that closely resembles human IVF, we investigated if vitrification of IVF embryos better preserves placental function and results in better pregnancy outcomes as compared to fresh ET because of transfer into a more physiologic endometrium. We found that the SO environment, independent of vitrification status, reduced implantation rates, inhibited placental mechanistic target of rapamycin signaling and induced placental stress signaling, resulting in fetal growth restriction (1.080 ± 0.05 g estrous fresh (n = 17 litters), 1.176 ± 0.05 g estrous vitrified (n = 12), 0.771 ± 0.06 g SO fresh (n = 15), 0.895 ± 0.08 g SO vitrified (n = 10), P < 0.0001). In addition, our study suggests that vitrification impairs the developmental potential of IVF blastocysts that resulted in a significantly smaller litter size (2.6 ± 2.3 fresh estrous vs 2.5 ± 2.4 fresh SO vs 1.6 ± 1.7 estrous vitrified vs 1.7 ± 1.8 SO vitrified, P = 0.019), with no effect on fetal growth or placental function at term. Our findings suggest that vitrification may negatively impact early embryonic viability, while the SO maternal uterine environment impairs both placental development and fetal growth in IVF.

Perfluoroalkyl Substances (PFAS) and Their Effects on the Placenta, Pregnancy, and Child Development: a Potential Mechanistic Role for Placental Peroxisome Proliferator-Activated Receptors (PPARs)

PURPOSE OF REVIEW

This review summarizes studies highlighting perfluoroalkyl substances (PFAS) and their effects on the placenta, pregnancy outcomes, and child health. It highlights human population-based associations as well as in vitro-based experimental data to inform an understanding of the molecular mechanisms underlying these health effects. Among the mechanisms by which PFAS may induce toxicity is via their interaction with the peroxisome proliferator-activated receptors (PPARs), nuclear receptors that regulate lipid metabolism and placental functions important to healthy pregnancies, as well as fetal and child development.

RECENT FINDINGS

In utero exposure to prevalent environmental contaminants such as PFAS is associated with negative health outcomes during pregnancy, birth outcomes, and later in life. Specifically, PFAS have been associated with increased incidence of gestational diabetes, childhood obesity, preeclampsia, and fetal growth restriction. In terms of placental molecular mechanisms underlying these associations, studies demonstrate that PFAS interfere with trophoblast lipid homeostasis, inflammation, and invasion. Moreover these effects could be mediated in part by the interaction between PFAS and PPARs, as well as other biological mechanisms. This review summarizes how PFAS, critical environmental contaminants, may contribute to diseases of pregnancy as well as early and later child health.

Perfluoroalkyl Substances (PFAS) and Their Effects on the Placenta, Pregnancy, and Child Development: a Potential Mechanistic Role for Placental Peroxisome Proliferator-Activated Receptors (PPARs)

PURPOSE OF REVIEW

This review summarizes studies highlighting perfluoroalkyl substances (PFAS) and their effects on the placenta, pregnancy outcomes, and child health. It highlights human population-based associations as well as in vitro-based experimental data to inform an understanding of the molecular mechanisms underlying these health effects. Among the mechanisms by which PFAS may induce toxicity is via their interaction with the peroxisome proliferator-activated receptors (PPARs), nuclear receptors that regulate lipid metabolism and placental functions important to healthy pregnancies, as well as fetal and child development.

RECENT FINDINGS

In utero exposure to prevalent environmental contaminants such as PFAS is associated with negative health outcomes during pregnancy, birth outcomes, and later in life. Specifically, PFAS have been associated with increased incidence of gestational diabetes, childhood obesity, preeclampsia, and fetal growth restriction. In terms of placental molecular mechanisms underlying these associations, studies demonstrate that PFAS interfere with trophoblast lipid homeostasis, inflammation, and invasion. Moreover these effects could be mediated in part by the interaction between PFAS and PPARs, as well as other biological mechanisms. This review summarizes how PFAS, critical environmental contaminants, may contribute to diseases of pregnancy as well as early and later child health.

Sex-specific difference in placental inflammatory transcriptional biomarkers of maternal phthalate exposure: a prospective cohort study

Previous epidemiologic research has shown that phthalate exposure in pregnant women is related to birth outcomes in a sex-specific manner. These outcomes may be mediated by placental inflammation, which is the proposed biological mechanism. This is the first study to address the relationship between phthalate exposure and gene expression in placental inflammation in a sex-specific manner. We performed quantitative PCR to measure placental inflammatory mRNAs (CRP, TNF-α, IL-1β, IL-6, IL-10, MCP-1, IL-8, CD68, and CD206) in 2469 placentae that were sampled at birth. We estimated the associations between mRNA and urinary phthalate monoesters using multiple linear regression models. Mono-n-butyl phthalate (MBP) was correlated with higher IL-1β, IL-6, and CRP expression in placentae of male fetuses and with higher IL-6, CRP, MCP-1, IL-8, IL-10, and CD68 expression in placentae of female fetuses. Mono benzyl phthalate (MBzP) increased the expression of TNF-α, MCP-1, and CD68 only in placentae of male fetuses. Mono (2-ethyl-5-oxohexyl) phthalate (MEOHP) was negatively correlated with CRP, MCP-1, and CD68 in placentae of female fetuses. Maternal phthalate exposure was associated with inflammatory variations in placental tissues. The associations were stronger in placentae of male than of female fetuses. Compared with the other metabolites, MBP plays a strong role in these associations. The placenta is worth being further investigated as a potential mediator of maternal exposure-induced disease risk in children.

Does early weaning shape future endocrine and metabolic disorders? Lessons from animal models

Obesity and its complications occur at alarming rates worldwide. Epidemiological data have associated perinatal conditions, such as malnutrition, with the development of some disorders, such as obesity, dyslipidemia, diabetes, and cardiovascular diseases, in childhood and adulthood. Exclusive breastfeeding has been associated with protection against long-term chronic diseases. However, in humans, the interruption of breastfeeding before the recommended period of 6 months is a common practice and can increase the risk of several metabolic disturbances. Nutritional and environmental changes within a critical window of development, such as pregnancy and breastfeeding, can induce permanent changes in metabolism through epigenetic mechanisms, leading to diseases later in life via a phenomenon known as programming or developmental plasticity. However, little is known regarding the underlying mechanisms by which precocious weaning can result in adipose tissue dysfunction and endocrine profile alterations. Here, the authors give a comprehensive report of the different animal models of early weaning and programming that can result in the development of metabolic syndrome. In rats, for example, pharmacological and nonpharmacological early weaning models are associated with the development of overweight and visceral fat accumulation, leptin and insulin resistance, and neuroendocrine and hepatic changes in adult progeny. Sex-related differences seem to influence this phenotype. Therefore, precocious weaning seems to be obesogenic for offspring. A better understanding of this condition seems essential to reducing the risk for diseases. Additionally, this knowledge can generate new insights into therapeutic strategies for obesity management, improving health outcomes.

Strength of nonhuman primate studies of developmental programming: review of sample sizes, challenges, and steps for future work

Nonhuman primate (NHP) studies are crucial to biomedical research. NHPs are the species most similar to humans in lifespan, body size, and hormonal profiles. Planning research requires statistical power evaluation, which is difficult to perform when lacking directly relevant preliminary data. This is especially true for NHP developmental programming studies, which are scarce. We review the sample sizes reported, challenges, areas needing further work, and goals of NHP maternal nutritional programming studies. The literature search included 27 keywords, for example, maternal obesity, intrauterine growth restriction, maternal high-fat diet, and maternal nutrient reduction. Only fetal and postnatal offspring studies involving tissue collection or imaging were included. Twenty-eight studies investigated maternal over-nutrition and 33 under-nutrition; 23 involved macaques and 38 baboons. Analysis by sex was performed in 19; minimum group size ranged from 1 to 8 (mean 4.7 ± 0.52, median 4, mode 3) and maximum group size from 3 to 16 (8.3 ± 0.93, 8, 8). Sexes were pooled in 42 studies; minimum group size ranged from 2 to 16 (mean 5.3 ± 0.35, median 6, mode 6) and maximum group size from 4 to 26 (10.2 ± 0.92, 8, 8). A typical study with sex-based analyses had group size minimum 4 and maximum 8 per sex. Among studies with sexes pooled, minimum group size averaged 6 and maximum 8. All studies reported some significant differences between groups. Therefore, studies with group sizes 3-8 can detect significance between groups. To address deficiencies in the literature, goals include increasing age range, more frequently considering sex as a biological variable, expanding topics, replicating studies, exploring intergenerational effects, and examining interventions.

Complex, coordinated and highly regulated changes in placental signaling and nutrient transport capacity in IUGR

The most common cause of intrauterine growth restriction (IUGR) in the developed world is placental insufficiency, a concept often used synonymously with reduced utero-placental and umbilical blood flows. However, placental insufficiency and IUGR are associated with complex, coordinated and highly regulated changes in placental signaling and nutrient transport including inhibition of insulin and mTOR signaling and down-regulation of specific amino acid transporters, Na+/K+-ATPase, the Na+/H+-exchanger, folate and lactate transporters. In contrast, placental glucose transport capacity is unaltered and Ca2+-ATPase activity and the expression of proteins involved in placental lipid transport are increased in IUGR. These findings are not entirely consistent with the traditional view that the placenta is dysfunctional in IUGR, but rather suggest that the placenta adapts to reduce fetal growth in response to an inability of the mother to allocate resources to the fetus. This new model has implications for the understanding of the mechanisms underpinning IUGR and for the development of intervention strategies.

Modulation of Placental Gene Expression in Small-for-Gestational-Age Infants

Small-for-gestational-age (SGA) infants are fetuses that have not reached their genetically programmed growth potential. Low birth weight predisposes these infants to an increased risk of developing cardiovascular, metabolic and neurodevelopmental conditions in later life. However, our understanding of how this pathology occurs is currently incomplete. Previous research has focused on understanding the transcriptome, epigenome and bacterial signatures separately. However, we hypothesise that interactions between moderators of gene expression are critical to understanding fetal growth restriction. Through a review of the current literature, we identify that there is evidence of modulated expression/methylation of the placental genome and the presence of bacterial DNA in the placental tissue of SGA infants. We also identify that despite limited evidence of the interactions between the above results, there are promising suggestions of a relationship between bacterial signatures and placental function. This review aims to summarise the current literature concerning fetal growth from multiple avenues and propose a novel relationship between the placental transcriptome, methylome and bacterial signature that, if characterised, may be able to improve our current understanding of the placental response to stress and the aetiology of growth restriction.

Maternal dyslipidemia during early pregnancy and epigenetic ageing of the placenta

Disruption of physiological ageing of the placenta is associated with obstetric complications. Altered lipid metabolism is a known trigger of tissue ageing, but the effect of maternal dyslipidemia on placental ageing is not clearly understood. We examined the relationship between maternal dyslipidemia and placental age acceleration (PAA), an epigenetic ageing measure derived from the difference between DNA methylation age and chronological gestational age. We also assessed whether the association varies by maternal pre-pregnancy obesity status and fetal sex. Placental data were obtained as part of the NICHD Fetal Growth Studies that involved participants from four race/ethnic groups. Placental DNA methylation age was estimated using 62 CpGs that have previously been found to have high placental age prediction accuracy. We used multivariable linear regression to test associations between maternal dyslipidemia during early gestation (i.e., high-density lipoprotein cholesterol (HDLc), low-density lipoprotein cholesterol (LDLc), total cholesterol (TChol), and triglycerides) and PAA adjusting for fetal sex and socio-demographic factors. Among normal-weight women, low HDLc, compared to high HDLc, was associated with 0.82 (95% CI: 0.00, 1.64) weeks higher PAA. Among women with female neonates, low HDLc, compared to high HDLc, was associated with 1.20 (95% CI: 0.17, 2.24) weeks higher PAA. High TChol was associated with 1.28 (95% CI: 0.12, 2.45) weeks higher PAA among Whites. In all, the study found that maternal dyslipidemia due to low HDLc was associated with accelerated epigenetic ageing of the placenta among mothers with normal pre-pregnancy weight and a female fetus.

Deletion of Prl7d1 causes placental defects at mid-pregnancy in mice

Prolactin family 7, subfamily d, member 1 (Prl7d1), a member of the expanding prolactin family, is mainly expressed in the placental junctional zone (including trophoblast giant cells and spongiotrophoblast cells) with peak expression observed at 12 days postcoitum (dpc) in mice. Previous studies have shown that PRL7D1 is a key mediator of angiogenesis in vitro; however, its physiological roles in placental development in vivo have not been characterized. To address this issue, we deleted Prl7d1 in mice and demonstrated that its absence results in reduced litter size and fertility. Histologically, Prl7d1 mutants exhibited striking placental abnormalities at 12.5 dpc, including a reduction in the proportion of labyrinth layers and a significant increase in decidual natural killer cells, glycogen trophoblasts, and trophoblast giant cells in the junctional zone. Moreover, placentas from Prl7d1-null mice displayed a thickened decidual spiral artery. Notably, these negative effects were more pronounced in male fetuses. Further RNA-sequencing analysis showed that Prl7d1 deletion results in significant differences in the placental transcriptome profile between the two sexes of fetuses. Together, this study demonstrates that Prl7d1 possesses antiangiogenic properties in deciduas and inhibits the development of junctional zone, which potentially alters the functional capacity of the placenta to support optimal fetal growth. Moreover, of note, the role of Prl7d1 in the placenta is regulated in a fetal sex-specific manner.

Analysis of serum changes in response to a high fat high cholesterol diet challenge reveals metabolic biomarkers of atherosclerosis

Atherosclerotic plaques are characterized by an accumulation of macrophages, lipids, smooth muscle cells, and fibroblasts, and, in advanced stages, necrotic debris within the arterial walls. Dietary habits such as high fat and high cholesterol (HFHC) consumption are known risk factors for atherosclerosis. However, the key metabolic contributors to diet-induced atherosclerosis are far from established. Herein, we investigate the role of a 2-year HFHC diet challenge in the metabolic changes of development and progression of atherosclerosis. We used a non-human primate (NHP) model (baboons, n = 60) fed a HFHC diet for two years and compared metabolomic profiles in serum from animals on baseline chow with serum collected after the challenge diet using two-dimensional gas chromatography time-of-flight mass-spectrometry (2D GC-ToF-MS) for untargeted metabolomic analysis, to quantify metabolites that contribute to atherosclerotic lesion formation. Further, clinical biomarkers associated with atherosclerosis, lipoprotein measures, fat indices, and arterial plaque formation (lesions) were quantified. Using two chemical derivatization (i.e., silylation) approaches, we quantified 321 metabolites belonging to 66 different metabolic pathways, which revealed significantly different metabolic profiles of HFHC diet and chow diet fed baboon sera. We found heritability of two important metabolites, lactic acid and asparagine, in the context of diet-induced metabolic changes. In addition, abundance of cholesterol, lactic acid, and asparagine were sex-dependent. Finally, 35 metabolites correlated (R2, 0.068-0.271, P < 0.05) with total lesion burden assessed in three arteries (aortic arch, common iliac artery, and descending aorta) which could serve as potential biomarkers pending further validation. This study demonstrates the feasibility of detecting sex-specific and heritable metabolites in NHPs with diet-induced atherosclerosis using untargeted metabolomics allowing understanding of atherosclerotic disease progression in humans.

Preclinical Models of Altered Early Life Nutrition and Development of Reproductive Disorders in Female Offspring

Early epidemiology studies in humans have and continue to offer valuable insight into the Developmental Origins of Health and Disease (DOHaD) hypothesis, which emphasises the importance of early-life nutritional and environmental changes on the increased risk of metabolic and reproductive disease in later life. Human studies are limited and constrained by a range of factors which do not apply to preclinical research. Animal models therefore offer a unique opportunity to fully investigate the mechanisms associated with developmental programming, helping to elucidate the developmental processes which influence reproductive diseases, and highlight potential biomarkers which can be translated back to the human condition. This review covers the use and limitations of a number of animal models frequently utilised in developmental programming investigations, with an emphasis on dietary manipulations which can lead to reproductive dysfunction in offspring.

nAChRs-ERK1/2-Egr-1 signaling participates in the developmental toxicity of nicotine by epigenetically down-regulating placental 11β-HSD2

Impaired placental 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2) activity which inactivates maternal glucocorticoids is associated with poor fetal growth and a higher risk of chronic diseases in adulthood. This study aimed to elucidate the epigenetically regulatory mechanism of nicotine on placental 11β-HSD2 expression. Pregnant Wistar rats were administered 1.0 mg/kg nicotine subcutaneously twice a day from gestational day 9 to 20. The results showed that prenatal nicotine exposure increased corticosterone levels in the placenta and fetal serum, disrupted placental morphology and endocrine function, and reduced fetal bodyweight. Meanwhile, histone modification abnormalities (decreased acetylation and increased di-methylation of histone 3 Lysine 9) on the HSD11B2 promoter and lower-expression of 11β-HSD2 were observed. Furthermore, the expression of nicotinic acetylcholine receptor (nAChR) α4/β2, the phosphorylation of extracellular regulated kinase 1/2 (ERK1/2) and Ets-like protein-1 (Elk-1), and the expression of early growth response-1 (Egr-1) were increased in the nicotine groups. In human BeWo cells, nicotine decreased 11β-HSD2 expression, increased nAChRα9 expression, and activated ERK1/2/Elk-1/Egr-1 signaling in the concentration (0.1-10 μM)-dependent manner. Antagonism of nAChRs, inhibition of ERK1/2 and Egr-1 knockdown by siRNA were able to block/abrogate the effects of nicotine on histone modification and expression of 11β-HSD2. Taken together, nicotine can impair placental structure and function, and induce fetal developmental toxicity. The underlying mechanism involves histone modifications and down-regulation of 11β-HSD2 through nAChRs/ERK1/2/Elk-1/Egr-1 signaling, which increases active glucocorticoids levels in the placenta and fetus, and eventually inhibits the fetal development.

Effects of Prenatal Nutrition and the Role of the Placenta in Health and Disease

Epidemiologic studies identified the linkage between exposures to stresses, including the type and plane of nutrition in utero with development of disease in later life. Given the critical roles of the placenta in mediating transport of nutrients between the mother and fetus and regulation of maternal metabolism, recent attention has focused on the role of the placenta in mediating the effect of altered nutritional exposures on the development of disease in later life. In this chapter we describe the mechanisms of nutrient transport in the placenta, the influence of placental metabolism on this, and how placental energetics influence placental function in response to a variety of stressors. Further the recent "recognition" that the placenta itself has a sex which affects its function may begin to help elucidate the mechanisms underlying the well-known dimorphism in development of disease in adult life.

Early sex-dependent differences in response to environmental stress

Developmental plasticity enables the appearance of long-term effects in offspring caused by exposure to environmental stressors during embryonic and foetal life. These long-term effects can be traced to pre- and post-implantation development, and in both cases, the effects are usually sex specific. During preimplantation development, male and female embryos exhibit an extensive transcriptional dimorphism mainly driven by incomplete X chromosome inactivation. These early developmental stages are crucial for the establishment of epigenetic marks that will be conserved throughout development, making it a particularly susceptible period for the appearance of long-term epigenetic-based phenotypes. Later in development, gonadal formation generates hormonal differences between the sexes, and male and female placentae exhibit different responses to environmental stressors. The maternal environment, including hormones and environmental insults during pregnancy, contributes to sex-specific placental development that controls genetic and epigenetic programming during foetal development, regulating sex-specific differences, including sex-specific epigenetic responses to environmental hazards, leading to long-term effects. This review summarizes several human and animal studies examining sex-specific responses to environmental stressors during both the periconception period (caused by differences in sex chromosome dosage) and placental development (caused by both sex chromosomes and hormones). The identification of relevant sex-dependent trajectories caused by sex chromosomes and/or sex hormones is essential to define diagnostic markers and prevention/intervention protocols.

Effect of moderate, 30 percent global maternal nutrient reduction on fetal and postnatal baboon phenotype

BACKGROUND

Most developmental programming studies on maternal nutrient reduction (MNR) are in altricial rodents whose maternal nutritional burden and offspring developmental trajectory differ from precocial non-human primates and humans.

METHODS

Control (CTR) baboon mothers ate ad libitum; MNR mothers ate 70% global control diet in pregnancy and lactation.

RESULTS

We present offspring morphometry, blood cortisol, and adrenocorticotropin (ACTH) during second half of gestation (G) and first three postnatal years. Moderate MNR produced intrauterine growth restriction (IUGR). IUGR males (n=43) and females (n=28) were smaller than CTR males (n=50) and females (n=47) in many measurements at many ages. In CTR, fetal ACTH increased 228% and cortisol 48% between 0.65G and 0.9G. IUGR ACTH was elevated at 0.65G and cortisol at 0.9G. 0.9G maternal gestational weight gain, fetal weight, and placenta weight were correlated.

CONCLUSIONS

Moderate IUGR decreased body weight and morphometric measurements at key time points and altered hypothalamo-pituitary-adrenal function.

Uterine remodelling during pregnancy and pseudopregnancy in the brushtail possum (Trichosurus vulpecula; Phalangeridae)

The formation of a placenta is critical for successful mammalian pregnancy and requires remodelling of the uterine epithelium. In eutherian mammals, remodelling involves specific morphological changes that often correlate with the mode of embryonic attachment. Given the differences between marsupial and eutherian placentae, formation of a marsupial placenta may involve patterns of uterine remodelling that are different from those in eutherians. Here we present a detailed morphological study of the uterus of the brushtail possum (Trichosurus vulpecula; Phalangeridae) throughout pregnancy, using both scanning and transmission electron microscopy, to identify whether uterine changes in marsupials correlate with mode of embryonic attachment as they do in eutherian mammals. The uterine remodelling of T. vulpecula is similar to that of eutherian mammals with the same mode of embryonic attachment (non-invasive, epitheliochorial placentation). The morphological similarities include development of large apical projections, and a decrease in the diffusion distance for haemotrophes around the period of embryonic attachment. Importantly, remodelling of the uterus in T. vulpecula during pregnancy differs from that of a marsupial species with non-invasive attachment (Macropus eugenii; Macropodidae) but is similar to that of a marsupial with invasive attachment (Monodelphis domestica; Didelphidae). We conclude that modes of embryonic attachment may not be typified by a particular suite of uterine changes in marsupials, as is the case for eutherian mammals, and that uterine remodelling may instead reflect phylogenetic relationships between marsupial lineages.

Maternal healthy lifestyle during early pregnancy and offspring birthweight: differences by offspring sex

PURPOSE

Individual maternal lifestyle factors during pregnancy have been associated with offspring birthweight; however, associations of combined lifestyle factors with birthweight and potential differences by offspring sex have not been examined.

MATERIALS AND METHODS

Participants (N = 2924) were identified from a pregnancy cohort in Washington state. Lifestyle factors during early pregnancy were dichotomized based on Alternate Healthy Eating Index score ≥62, leisure time physical activity (LTPA) ≥ 150 min/week, not smoking during pregnancy and Perceived Stress Scale score ≤3, then combined into a lifestyle score (0-4). Regression models were run overall and stratified by offspring sex, prepregnancy overweight/obese (BMI ≥25 kg/m²) and prepregnancy LTPA.

RESULTS

Overall, 20% of participants had healthy diet, 95% were nonsmokers, 55% had low stress levels, and 66% were physically active. Lifestyle score was not associated with birthweight (β = 3.3 g; 95% CI: -14.5, 21.0); however, associations differed by offspring sex (p = .009). For each unit increase in lifestyle score, there was a suggested 22.4 g higher birthweight (95% CI: -2.7, 47.6) among males and 14.6 g lower birthweight (95% CI: -39.9, 10.7) among females. Prepregnancy BMI and LTPA did not modify associations.

CONCLUSIONS

Healthy lifestyle score in early pregnancy may be associated with greater birthweight among male offspring, but lower birthweight among female offspring.

High Fat Diets Sex-Specifically Affect the Renal Transcriptome and Program Obesity, Kidney Injury, and Hypertension in the Offspring

Obesity and related disorders have increased concurrently with an increased consumption of saturated fatty acids. We examined whether post-weaning high fat (HF) diet would exacerbate offspring vulnerability to maternal HF-induced programmed hypertension and kidney disease sex-specifically, with a focus on the kidney. Next, we aimed to elucidate the gene–diet interactions that contribute to maternal HF-induced renal programming using the next generation RNA sequencing (NGS) technology. Female Sprague-Dawley rats received either a normal diet (ND) or HF diet (D12331, Research Diets) for five weeks before the delivery. The offspring of both sexes were put on either the ND or HF diet from weaning to six months of age, resulting in four groups of each sex (maternal diet/post-weaning diet; n = 5–7/group): ND/ND, ND/HF, HF/ND, and HF/HF. Post-weaning HF diet increased bodyweights of both ND/HF and HF/HF animals from three to six months only in males. Post-weaning HF diet increased systolic blood pressure in male and female offspring, irrespective of whether they were exposed to maternal HF or not. Male HF/HF offspring showed greater degrees of glomerular and tubular injury compared to the ND/ND group. Our NGS data showed that maternal HF diet significantly altered renal transcriptome with female offspring being more HF-sensitive. HF diet induced hypertension and renal injury are associated with oxidative stress, activation of renin-angiotensin system, and dysregulated sodium transporters and circadian clock. Post-weaning HF diet sex-specifically exacerbates the development of obesity, kidney injury, but not hypertension programmed by maternal HF intake. Better understanding of the sex-dependent mechanisms that underlie HF-induced renal programming will help develop a novel personalized dietary intervention to prevent obesity and related disorders.

Developmental Origins of Chronic Kidney Disease: Should We Focus on Early Life?

Chronic kidney disease (CKD) is becoming a global burden, despite recent advances in management. CKD can begin in early life by so-called "developmental programming" or "developmental origins of health and disease" (DOHaD). Early-life insults cause structural and functional changes in the developing kidney, which is called renal programming. Epidemiological and experimental evidence supports the proposition that early-life adverse events lead to renal programming and make subjects vulnerable to developing CKD and its comorbidities in later life. In addition to low nephron endowment, several mechanisms have been proposed for renal programming. The DOHaD concept opens a new window to offset the programming process in early life to prevent the development of adult kidney disease, namely reprogramming. Here, we review the key themes on the developmental origins of CKD. We have particularly focused on the following areas: evidence from human studies support fetal programming of kidney disease; insight from animal models of renal programming; hypothetical mechanisms of renal programming; alterations of renal transcriptome in response to early-life insults; and the application of reprogramming interventions to prevent the programming of kidney disease.

Influence of moderate maternal nutrition restriction on the fetal baboon metabolome at 0.5 and 0.9 gestation

BACKGROUND AND AIMS

Moderately reduced maternal nutrient availability during pregnancy has adverse effects on the fetuses' growth and metabolism during and after pregnancy. The aim of this study was to explore effects of maternal nutrition restriction (MNR) on key metabolites of the fetal energy metabolism, particularly amino acids (AA), nonesterified fatty acids (NEFA), acylcarnitines and phospholipids. These effects may reflect mechanisms relating MNR to later adverse outcomes.

METHODS AND RESULTS

Plasma and liver samples of fetal baboons, whose mothers were fed ad libitum (CTR) or MNR (70% of CTR), were collected at 0.5 and 0.9 gestation (G - term 184 days). Metabolites were measured with liquid chromatography coupled to mass spectrometry. In both, CTR and MNR, fetal metabolic profiles changed markedly between 0.5G and 0.9G. Fetal liver glucose concentrations were strongly increased. Hepatic levels of NEFA, sphingomyelins, and alkyl-linked phospholipids increased while plasma NEFA and acyl-linked phospholipids levels decreased with progression of gestation. At 0.5G, MNR fetal plasma levels of short- and medium-chain acylcarnitines were elevated, but did no longer differ between groups at 0.9G. At 0.9G, plasma levels of methionine and threonine as well as hepatic threonine levels were lower in the MNR group.

CONCLUSION

Small differences in the concentrations of plasma and liver metabolites between MNR and CTR fetuses reflect good adaptation to MNR. Fetal liver metabolic profiles changed markedly between the two gestation stages, reflecting enhanced liver glucose and lipid levels with advancing gestation. Decreased concentrations of AA suggest an up-regulation of gluconeogenesis in MNR.

Aliskiren Administration during Early Postnatal Life Sex-Specifically Alleviates Hypertension Programmed by Maternal High Fructose Consumption

Key points summary

Maternal high-fructose (HF) induces programmed hypertension in adult offspring.

Early aliskiren administration prevents HF-induced hypertension in both sexes of adult offspring.

HF regulates RAS components in the offspring kidney in a sex-specific manner.

HF alters renal transcriptome, with female offspring being more sensitive.

Deprogramming strategy to prevent hypertension might be sex-specific.

Background: Maternal high fructose (HF) intake induced renal programming and hypertension in male adult offspring. We examined whether maternal HF intake causes programmed hypertension and whether aliskiren administration confers protection against the process in a sex-specific manner, with a focus on the transcriptome changes in the kidney using next-generation RNA sequencing (NGS) technology and renin-angiotensin system (RAS).

Methods: Pregnant Sprague—Dawley rats received regular chow or chow supplemented with 60% fructose throughout pregnancy and lactation. Offspring were assigned to six groups: male control, male HF (MHF), MHF+Aliskiren, female control, female HF (FHF), and FHF+Aliskiren. Oral aliskiren 10 mg/kg/day was administered via gastric gavage between 2 and 4 weeks of age. Rats were sacrificed at 12 weeks of age.

Results: Maternal HF intake induced programmed hypertension in 12-week-old offspring of both sexes. HF regulated renal transcriptome and RAS components in the offspring kidney in a sex-specific manner. Aliskiren administration prevented HF-induced programmed hypertension in both sexes of adult offspring. Aliskiren administration increased ACE2 and MAS protein levels in female kidneys exposed to maternal HF intake.

Conclusion: Maternal HF induced programmed hypertension in both sexes of adult offspring, which was sex-specifically mitigated by early aliskiren administration. Better understanding of the sex-dependent mechanisms that underlie maternal HF-induced renal programming will help develop a novel sex-specific strategy to prevent programmed hypertension.

Placental changes caused by food restriction during early pregnancy in mice are reversible

In a previous study, 50% calorie restriction in mice from d1.5 to 11.5 of pregnancy resulted in reduced placental weights and areas,relative sparing of labyrinth zone area compared to junctional zone area, and dramatic changes in global gene expression profiles.However, little lasting effect was seen on adult offspring of these pregnancies, with a slight reduction in adiposity in males and some changes in liver gene expression in both sexes. The goals of the present study were to determine whether the placental changes induced by caloric restriction in early pregnancy had permanent, irreversible effects on the placenta, and whether the changes in liver gene expression in adult offspring were present before birth. There were no differences in placental weights or areas, or the areas of individual placental zones near term in mice that had previously been food restricted. Global gene expression profiles at d18.5 were indistinguishable in placentas from control and previously food-restricted mothers. In fetuses from restricted dams at d18.5, liver expression of Gck, a key regulator of glycogen synthesis, was reduced, whereas its expression was increased in livers from adult offspring of restricted dams. Ppara expression was also reduced in fetal livers from restricted dams at d18.5, but not in adult offspring livers. We conclude that alterations in the placenta caused by nutrient restriction in early pregnancy are reversible, and that alterations in gene expression in livers of adult offspring are not a result of changes initiated during pregnancy and maintained through adulthood.

[Epigenetics and Nutrition: maternal nutrition impacts on placental development and health of offspring]

The environment, defined broadly by all that is external to the individual, conditions the phenotype during development, particularly the susceptibility to develop non-communicable diseases. This notion, called Developmental Origins of Health and Disease (DOHaD), is based on numerous epidemiological studies as well as animal models. Thus, parental nutrition and obesity can predispose the offspring to develop metabolic and cardiovascular diseases in adulthood. The known underlying mechanisms include an altered development of tissues that adapt to maternal metabolic condition, and a placental dysfunction, which in turn impacts fetal growth and development. Epigenetic mechanisms modulate gene expression without affecting the DNA sequence itself. The main epigenetic marks are DNA methylation and histone post-translational modifications. These marks are erased and set-up during gametogenesis and development in order to ensure cellular identity. Therefore, they can lead to a memorisation of early environment and induce long-term alteration of cell and tissue functions, which will condition the susceptibility to non-communicable diseases. The placenta is a programming agent of adult disease. The environment, such as smoking or psychosocial stress, is able to modify epigenetic processes in placenta, such as small RNA expression and DNA methylation. We showed that placenta is sensitive to maternal obesity and maternal nutrition, in terms of histology, transcription and epigenetic marks. A clear sexual dimorphism is remarkable in the placental response to maternal environment. In adulthood, the phenotype is also different between males and females. Epigenetic mechanisms could underlie this differential response of males and females to the same environment. The DOHaD can no longer be ignored in Biology of Reproduction. The prevention of non-communicable diseases must take this new paradigm into account. Research will allow a better comprehension of the mechanisms of this early conditioning and the marked sexual dimorphism it is associated to.

Sex-Specific Placental Responses in Fetal Development

The placenta is an ephemeral but critical organ for the survival of all eutherian mammals and marsupials. It is the primary messenger system between the mother and fetus, where communicational signals, nutrients, waste, gases, and extrinsic factors are exchanged. Although the placenta may buffer the fetus from various environmental insults, placental dysfunction might also contribute to detrimental developmental origins of adult health and disease effects. The placenta of one sex over the other might possess greater ability to respond and buffer against environmental insults. Given the potential role of the placenta in effecting the lifetime health of the offspring, it is not surprising that there has been a resurging interest in this organ, including the Human Placental Project launched by the National Institutes of Child Health and Human Development. In this review, we will compare embryological development of the laboratory mouse and human chorioallantoic placentae. Next, evidence that various species, including humans, exhibit normal sex-dependent structural and functional placental differences will be examined followed by how in utero environmental changes (nutritional state, stress, and exposure to environmental chemicals) might interact with fetal sex to affect this organ. Recent data also suggest that paternal state impacts placental function in a sex-dependent manner. The research to date linking placental maladaptive responses and later developmental origins of adult health and disease effects will be explored. Finally, we will focus on how sex chromosomes and epimutations may contribute to sex-dependent differences in placental function, the unanswered questions, and future directions that warrant further consideration.

Sex differences in the early life correlates of natural antibody concentrations

Innate-like B1a lymphocytes arise from long-lived progenitors produced exclusively by fetal stem cells. Any insults coinciding with this early lymphopoietic wave could have a permanent impact on the B1a population and its unique protein products, the natural antibodies (NAb). We investigated early life nutritional influences on NAb concentrations of pre-adolescent children (n=290) in rural Nepal for whom we had extensive information on exposures from pregnancy and early infancy. Infant size and growth were strongly associated with NAb concentrations at 9-13 years of age among males (e.g., for neonatal weight: βBOYS=0.43; P<0.001), but not females (e.g., for neonatal weight: βGIRLS=-0.16; P=0.26). In females, season of birth was associated with NAb concentrations, with marked reductions among girls born during the pre-monsoon (March-May; βGIRLS=-0.39; P=0.01) and pre-harvest (September-November; βGIRLS=-0.35; P=0.03) seasons. Our findings suggest that nutritional or other environmental influences on immune development may vary by sex, with potential consequences for immune function during infancy and long-term risk of immune-mediated disease.

The baboon (Papio sp.) as a model for female reproduction studies

BIOLOGY AND REPRODUCTION

Due to their size and anatomical similarity to humans, baboons make an excellent model for reproductive studies. Baboons have a simple short cervix, muscular uterus, ovaries just lateral to the uterus and similar vasculature to that of humans. Because of the size of the animals, instruments designed for use in women can be readily used on baboons. Noninvasive determination of phase of estrous cycle is readily made by observation of changes in perineal sexual skin turgor and color.

ADVANTAGES

Some advantages of use of baboons compared to other nonhuman primates is that they are nonseasonal breeders allowing for studies to be conducted year round, have minimal infectious disease risks to humans as they do not carry Herpes B and have a social structure allowing for easy group formation. Baboons serve as good models for many conditions in humans and should be considered for studies investigating reproductive issues.

Placental contribution to nutritional programming of health and diseases: epigenetics and sexual dimorphism

The recent and rapid worldwide increase in non-communicable diseases challenges the assumption that genetic factors are the primary contributors to such diseases. A new concept of the ‘developmental origins of health and disease’ (DOHaD) is at stake and therefore requires a paradigm shift. Maternal obesity and malnutrition predispose offspring to develop metabolic syndrome, a vicious cycle leading to transmission to subsequent generation(s), with differences in response and susceptibility according to the sex of the individual. The placenta is a programming agent of adult health and disease. Adaptations of placental phenotype in response to maternal diet and metabolic status alter fetal nutrient supply. This implies important epigenetic changes that are, however, still poorly documented in DOHaD studies, particularly concerning overnutrition. The aim of this review is to discuss the emerging knowledge on the relationships between the effect of maternal nutrition or metabolic status on placental function and the risk of diseases later in life, with a specific focus on epigenetic mechanisms and sexual dimorphism. Explaining the sex-specific causal variables and how males versus females respond and adapt to environmental perturbations should help physicians and patients to anticipate disease susceptibility.

Placental Evolution within the Supraordinal Clades of Eutheria with the Perspective of Alternative Animal Models for Human Placentation

Here a survey of placental evolution is conducted. Placentation is a key factor for the evolution of placental mammals that had evolved an astonishing diversity. As a temporary organ that does not allow easy access, it is still not well understood. The lack of data also is a restriction for better understanding of placental development, structure, and function in the human. Animal models are essential, because experimental access to the human placenta is naturally restricted. However, there is not a single ideal model that is entirely similar to humans. It is particularly important to establish other models than the mouse, which is characterised by a short gestation period and poorly developed neonates that may provide insights only for early human pregnancy. In conclusion, current evolutionary studies have contributed essentially to providing a pool of experimental models for recent and future approaches that may also meet the requirements of a long gestation period and advanced developmental status of the newborn in the human. Suitability and limitations of taxa as alternative animal models are discussed. However, further investigations especially in wildlife taxa should be conducted in order to learn more about the full evolutionary plasticity of the placenta system.

Maternal-fetal nutrient transport in pregnancy pathologies: the role of the placenta

Appropriate in utero growth is essential for offspring development and is a critical contributor to long-term health. Fetal growth is largely dictated by the availability of nutrients in maternal circulation and the ability of these nutrients to be transported into fetal circulation via the placenta. Substrate flux across placental gradients is dependent on the accessibility and activity of nutrient-specific transporters. Changes in the expression and activity of these transporters is implicated in cases of restricted and excessive fetal growth, and may represent a control mechanism by which fetal growth rate attempts to match availability of nutrients in maternal circulation. This review provides an overview of placenta nutrient transport with an emphasis on macro-nutrient transporters. It highlights the changes in expression and activity of these transporters associated with common pregnancy pathologies, including intrauterine growth restriction, macrosomia, diabetes and obesity, as well as the potential impact of maternal diet. Molecular signaling pathways linking maternal nutrient availability and placenta nutrient transport are discussed. How sexual dimorphism affects fetal growth strategies and the placenta’s response to an altered intrauterine environment is considered. Further knowledge in this area may be the first step in the development of targeted interventions to help optimize fetal growth.

Why primate models matter

Research involving nonhuman primates (NHPs) has played a vital role in many of the medical and scientific advances of the past century. NHPs are used because of their similarity to humans in physiology, neuroanatomy, reproduction, development, cognition, and social complexity-yet it is these very similarities that make the use of NHPs in biomedical research a considered decision. As primate researchers, we feel an obligation and responsibility to present the facts concerning why primates are used in various areas of biomedical research. Recent decisions in the United States, including the phasing out of chimpanzees in research by the National Institutes of Health and the pending closure of the New England Primate Research Center, illustrate to us the critical importance of conveying why continued research with primates is needed. Here, we review key areas in biomedicine where primate models have been, and continue to be, essential for advancing fundamental knowledge in biomedical and biological research.

Maternal overnutrition programs changes in the expression of skeletal muscle genes that are associated with insulin resistance and defects of oxidative phosphorylation in adult male rat offspring

Children of obese mothers have increased risk of metabolic syndrome as adults. Here we report the effects of a high-fat diet in the absence of maternal obesity at conception on skeletal muscle metabolic and transcriptional profiles of adult male offspring. Female Sprague Dawley rats were fed a diet rich in saturated fat and sucrose [high-fat diet (HFD): 23.5% total fat, 9.83% saturated fat, 20% sucrose wt:wt] or a normal control diet [(CD) 7% total fat, 0.5% saturated fat, 10% sucrose wt:wt] for the 3 wk prior to mating and throughout pregnancy and lactation. Maternal weights were not different at conception; however, HFD-fed dams were 22% heavier than controls during pregnancy. On a normal diet, the male offspring of HFD-fed dams were not heavier than controls but demonstrated features of insulin resistance, including elevated plasma insulin concentration [40.1 ± 2.5 (CD) vs 56.2 ± 6.1 (HFD) mU/L; P = 0.023]. Next-generation mRNA sequencing was used to identify differentially expressed genes in the offspring soleus muscle, and gene set enrichment analysis (GSEA) was used to detect coordinated changes that are characteristic of a biological function. GSEA identified 15 upregulated pathways, including cytokine signaling (P < 0.005), starch and sucrose metabolism (P < 0.017), inflammatory response (P < 0.024), and cytokine-cytokine receptor interaction (P < 0.037). A further 8 pathways were downregulated, including oxidative phosphorylation (P < 0.004), mitochondrial matrix (P < 0.006), and electron transport/uncoupling (P < 0.022). Phosphorylation of the insulin signaling protein kinase B was reduced [2.86 ± 0.63 (CD) vs 1.02 ± 0.27 (HFD); P = 0.027] and mitochondrial complexes I, II, and V protein were downregulated by 50-68% (P < 0.005). On a normal diet, the male offspring of HFD-fed dams did not become obese adults but developed insulin resistance, with transcriptional evidence of muscle cytokine activation, inflammation, and mitochondrial dysfunction. These data indicate that maternal overnutrition, even in the absence of prepregnancy obesity, can promote metabolic dysregulation and predispose offspring to type 2 diabetes.