Improving amino acid nutrition to prevent intrauterine growth restriction in mammals

Intrauterine growth restriction (IUGR) is one of the most common concerns in human obstetrics and domestic animal production. It is usually caused by placental insufficiency, which decreases fetal uptake of nutrients (especially amino acids) from the placenta. Amino acids are not only building blocks for protein but also key regulators of metabolic pathways in fetoplacental development. The enhanced demands of amino acids by the developing conceptus must be met via active transport systems across the placenta as normal pregnancy advances. Growing evidence indicates that IUGR is associated with a reduction in placental amino acid transport capacity and metabolic pathways within the embryonic/fetal development. The positive relationships between amino acid concentrations in circulating maternal blood and placental amino acid transport into fetus encourage designing new therapies to prevent or treat IUGR by enhancing amino acid availability in maternal diets or maternal circulation. Despite the positive effects of available dietary interventions, nutritional therapy for IUGR is still in its infancy. Based on understanding of the underlying mechanisms whereby amino acids promote fetal growth and of their dietary requirements by IUGR, supplementation with functional amino acids (e.g., arginine and glutamine) hold great promise for preventing fetal growth restriction and improving health and growth of IUGR offspring.     

Synergistic effects of prenatal hypoxia and postnatal high-fat diet in the development of cardiovascular pathology in young rats

We have previously shown that adult offspring exposed to a prenatal hypoxic insult leading to intrauterine growth restriction (IUGR) are more susceptible to cardiovascular pathologies. Our objectives were to evaluate the interaction between hypoxia-induced IUGR and postnatal diet in the early development of cardiovascular pathologies. Furthermore, we sought to determine whether the postnatal administration of resveratrol could prevent the development of cardiovascular disorders associated with hypoxia-induced IUGR. On day 15 of pregnancy, Sprague-Dawley rats were randomly assigned to hypoxia (11.5% oxygen), to induce IUGR, or normal oxygen (control) groups. For study A, male offspring (3 wk of age) were randomly assigned a low-fat (LF, <10% fat) or a high-fat (HF, 45% fat) diet. For study B, offspring were randomized to either HF or HF+resveratrol diets. After 9 wk, cardiac and vascular functions were evaluated. Prenatal hypoxia and HF diet were associated with an increased myocardial susceptibility to ischemia. Blood pressure, in vivo cardiac function, and ex vivo vascular function were not different among experimental groups; however, hypoxia-induced IUGR offspring had lower resting heart rates. Our results suggest that prenatal insults can enhance the susceptibility to a second hit such as myocardial ischemia, and that this phenomenon is exacerbated, in the early stages of life by nutritional stressors such as a HF diet. Supplementing HF diets with resveratrol improved cardiac tolerance to ischemia in offspring born IUGR but not in controls. Thus we conclude that the additive effect of prenatal (hypoxia-induced IUGR) and postnatal (HF diet) factors can lead to the earlier development of cardiovascular pathology in rats, and postnatal resveratrol supplementation prevented the deleterious cardiovascular effects of HF diet in offspring exposed to prenatal hypoxia.     

Long‐term Effects of Prenatal Stress and Glucocorticoid Exposure

There is a growing body of evidence suggesting that events during prenatal life can have long‐lasting effects on development and adult health. Stress during pregnancy is common and has been linked to increased incidence of a range of affective and behavioral outcomes in the offspring in later life and also some somatic outcomes. Glucocorticoids, and their actions on the fetus, which are regulated by placental 11β‐hydroxysteroid dehydrogenase type 2 (11β‐HSD2), are hypothesized to mediate these effects. Animal studies have demonstrated long‐term effects of stress and glucocorticoid administration on behavioral outcomes, as well as increased blood pressure, altered hypothalamic pituitary adrenal axis (HPA) function, and decreased glucose tolerance and brain size. In humans, licorice, which inhibits placental 11β‐HSD2 when consumed during pregnancy, has been shown to increase the risk of behavioral problems linked to altered HPA activity. Synthetic glucocorticoids administered during pregnancy to improve fetal lung maturity in threatened preterm birth have been shown to reduce birth weight and head circumference, but have not been linked to grosschanges in long‐term health todate. It is important to consider thelong‐term consequences of stress, and medication that mimics stress, during pregnancy. Birth Defects Research (PartC) 96:315–324, 2012. © 2013 Wiley Periodicals, Inc.     

Postnatal growth restriction and gene expression changes in a mouse model of fetal alcohol syndrome

Growth restriction, craniofacial dysmorphology, and central nervous system defects are the main diagnostic features of fetal alcohol syndrome. Studies in humans and mice have reported that the growth restriction can be prenatal or postnatal, but the underlying mechanisms remain unknown.We recently described a mouse model of moderate gestational ethanol exposure that produces measurable phenotypes in line with fetal alcohol syndrome (e.g., craniofacial changes and growth restriction in adolescent mice). In this study, we characterize in detail the growth restriction phenotype by measuring body weight at gestational day 16.5, cross-fostering from birth to weaning, and by extending our observations into adulthood. Furthermore, in an attempt to unravel the molecular events contributing to the growth phenotype, we have compared gene expression patterns in the liver and kidney of nonfostered, ethanol-exposed and control mice at postnatal day 28.We find that the ethanol-induced growth phenotype is not detectable prior to birth, but is present at weaning, even in mice that have been cross-fostered to unexposed dams. This finding suggests a postnatal growth restriction phenotype that is not due to deficient postpartum care by dams that drank ethanol, but rather a physiologic result of ethanol exposure in utero. We also find that, despite some catch-up growth after 5 weeks of age, the effect extends into adulthood, which is consistent with longitudinal studies in humans.Genome-wide gene expression analysis revealed interesting ethanol-induced changes in the liver, including genes involved in the metabolism of exogenous and endogenous compounds, iron homeostasis, and lipid metabolism.     

Maternal protein restriction during lactation induces early and lasting plasma metabolomic and hepatic lipidomic signatures of the offspring in a rodent programming model

Perinatal undernutrition affects not only fetal and neonatal growth but also adult health outcome, as suggested by the metabolic imprinting concept. However, the exact mechanisms underlying offspring metabolic adaptations are not yet fully understood. Specifically, it remains unclear whether the gestation or the lactation is the more vulnerable period to modify offspring metabolic flexibility. We investigated in a rodent model of intrauterine growth restriction (IUGR) induced by maternal protein restriction (R) during gestation which time window of maternal undernutrition (gestation, lactation or gestation–lactation) has more impact on the male offspring metabolomics phenotype. Plasma metabolome and hepatic lipidome of offspring were characterized through suckling period and at adulthood using liquid chromatography–high-resolution mass spectrometry. Multivariate analysis of these fingerprints highlighted a persistent metabolomics signature in rats suckled by R dams, with a clear-cut discrimination from offspring fed by control (C) dams. Pups submitted to a nutritional switch at birth presented a metabolomics signature clearly distinct from that of pups nursed by dams maintained on a consistent perinatal diet. Control rats suckled by R dams presented transiently higher branched-chain amino acid (BCAA) oxidation during lactation besides increased fatty acid (FA) β-oxidation, associated with preserved insulin sensitivity and lesser fat accretion that persisted throughout their life. In contrast, IUGR rats displayed permanently impaired β-oxidation, associated to increased glucose or BCAA oxidation at adulthood, depending on the fact that pups experienced slow postnatal or catch-up growth, as suckled by R or C dams, respectively. Taken together, these findings provide evidence for a significant contribution of the lactation period in metabolic programming.     

Intrauterine growth retardation increases the susceptibility of pigs to high-fat diet-induced mitochondrial dysfunction in skeletal muscle

It has been recognized that there is a relationship between prenatal growth restriction and the development of metabolic-related diseases in later life, a process involved in mitochondrial dysfunction. In addition, intrauterine growth retardation (IUGR) increases the susceptibility of offspring to high-fat (HF) diet-induced metabolic syndrome. Recent findings suggested that HF feeding decreased mitochondrial oxidative capacity and impaired mitochondrial function in skeletal muscle. Therefore, we hypothesized that the long-term consequences of IUGR on mitochondrial biogenesis and function make the offspring more susceptible to HF diet-induced mitochondrial dysfunction. Normal birth weight (NBW), and IUGR pigs were allotted to control or HF diet in a completely randomized design, individually. After 4 weeks of feeding, growth performance and molecular pathways related to mitochondrial function were determined. The results showed that IUGR decreased growth performance and plasma insulin concentrations. In offspring fed a HF diet, IUGR was associated with enhanced plasma leptin levels, increased concentrations of triglyceride and malondialdehyde (MDA), and reduced glycogen and ATP contents in skeletal muscle. High fat diet-fed IUGR offspring exhibited decreased activities of lactate dehydrogenase (LDH) and glucose-6-phosphate dehydrogenase (G6PD). These alterations in metabolic traits of IUGR pigs were accompanied by impaired mitochondrial respiration function, reduced mitochondrial DNA (mtDNA) contents, and down-regulated mRNA expression levels of genes responsible for mitochondrial biogenesis and function. In conclusion, our results suggest that IUGR make the offspring more susceptible to HF diet-induced mitochondrial dysfunction.     

The effects of prenatal and postnatal environmental interaction: Prenatal environmental adaptation hypothesis

Adverse antenatal maternal environments during pregnancy influence fetal development that consequently increases risks of mental health problems including psychiatric disorders in offspring. Therefore, behavioral and brain alterations caused by adverse prenatal environmental conditions are generally considered as deficits. In this article, we propose a novel hypothesis, along with summarizing a body of literatures supporting it, that fetal neurodevelopmental alterations, particularly synaptic network changes occurring in the prefrontal cortex, associated with adverse prenatal environmental conditions may be adaptation to cope with expected severe postnatal environments, and therefore, psychiatric disorders may be able to be understood as adaptive strategies against severe environmental conditions through evolution. It is hoped that the hypothesis presented in this article stimulates and opens a new venue on research toward understanding of biological mechanisms and therapeutic treatments of psychiatric disorders.     

The impact of maternal obesity in pregnancy on placental glucocorticoid and macronutrient transport and metabolism

Maternal obesity is the most common metabolic disturbance in pregnancy affecting >1 in 5 women in some countries. Babies born to obese women are heavier with more adiposity at birth, and are vulnerable to obesity and metabolic disease across the lifespan suggesting offspring health is ‘programmed’ by fetal exposure to an obese intra-uterine environment. The placenta plays a major role in dictating the impact of maternal health on prenatal development. Maternal obesity impacts the function of integral placental receptors and transporters for glucocorticoids and nutrients, key drivers of fetal growth, though mechanisms remain poorly understood. This review aims to summarise current knowledge in this area, and considers the impact of obesity on the epigenetic machinery of the placenta at this vital juncture in offspring development. Further research is required to advance understanding of these areas in the hope that the trans-generational cycle of obesity can be alleviated.     

Glucose metabolic adaptations in the intrauterine growth-restricted adult female rat offspring

We studied glucose metabolic adaptations in the intrauterine growth-restricted (IUGR) rat offspring to decipher glucose homeostasis in metabolic programming. Glucose futile cycling (GFC), which is altered when there is imbalance between glucose production and utilization, was studied during a glucose tolerance test (GTT) in 2-day-old (n = 8), 2-mo-old (n = 22), and 15-mo-old (n = 22) female rat offspring. The IUGR rats exposed to either prenatal (CM/SP, n = 5 per age), postnatal (SM/CP, n = 6), or pre- and postnatal (SM/SP, n = 6) nutrient restriction were compared with age-matched controls (CM/CP, n = 5). At 2 days, IUGR pups (SP) were smaller and glucose intolerant and had increased hepatic glucose production and increased glucose disposal (P < 0.01) compared with controls (CP). At 2 mo, the GTT, glucose clearance, and GFC did not change. However, a decline in hepatic glucose-6-phosphatase (P < 0.05) and fructose-1,6-biphosphatase (P < 0.05) enzyme activities in the IUGR offspring was detected. At 15 mo, prenatal nutrient restriction (CM/SP) resulted in greater weight gain (P < 0.01) and hyperinsulinemia (P < 0.001) compared with postnatal nutrient restriction (SM/CP). A decline in GFC in the face of a normal GTT occurred in both the prenatal (CM/SP, P < 0.01) and postnatal calorie (SM/CP, P < 0.03) and growth-restricted offspring. The IUGR offspring with pre- and postnatal nutrient restriction (SM/SP) were smaller, hypoinsulinemic (P < 0.03), and hypoleptinemic (P < 0.03), with no change in GTT, hepatic glucose production, GFC, or glucose clearance. We conclude that there is pre- and postnatal programming that affects the postnatal compensatory adaptation of GFC and disposal initiated by changes in circulating insulin concentrations, thereby determining hepatic insulin sensitivity in a phenotype-specific manner.     

You are what your dad ate

Maternal nutrition and metabolism are critical determinants of adult offspring health. Recent reports describe adverse offspring outcomes associated with the father's diet, indicating nongenetic inheritance of paternal experience. Determining underlying mechanisms may require reconsideration of our understanding of the heritability of epigenetic states.     

Intrauterine growth restriction leads to changes in sulfur amino acid metabolism, but not global DNA methylation, in Yucatan miniature piglets

Intrauterine growth restriction (IUGR), in both animals and humans, has been linked to metabolic syndrome later in life. There has been recent evidence that perturbations in sulfur amino acid metabolism may be involved in this early programming phenomenon. Methionine is the precursor for cellular methylation reactions and for the synthesis of cysteine. It has been suggested that the mechanism behind the "fetal origins" of adult diseases may be epigenetic, involving DNA methylation. Because we have recently demonstrated the fetal origins phenomenon in Yucatan miniature swine, we hypothesized that sulfur amino acid metabolism is altered in IUGR piglets. In this study, metabolites and the activities of sulfur amino acid cycle enzymes were analyzed in liver samples of 3- to 5-day-old runt (IUGR: 0.85±0.13 kg) and large (1.36±0.21 kg) Yucatan miniature pig littermates (n=6 pairs). The IUGR piglets had significantly lower specific and total activities of betaine-homocysteine methyltransferase (BHMT) and cystathionine γ-lyase (CGL) than larger littermates (P<.05). Expression of CGL (but not BHMT) mRNA was also lower in IUGR piglets (P<.05). This low CGL reduced cysteine and taurine concentrations in IUGR pigs and led to an accumulation of hepatic cystathionine, with lower homocysteine concentrations. Methylation index and liver global DNA methylation were unaltered. Reduced prenatal growth in Yucatan miniature piglets impairs their remethylation capacity as well as their ability to remove cystathionine and synthesize cysteine and taurine, which could have important implications on long-term health outcomes of IUGR neonates.     

Sedentary behavior during postnatal life is determined by the prenatal environment and exacerbated by postnatal hypercaloric nutrition

The discovery of a link between in utero experience and later metabolic and cardiovascular disease is one of the most important advances in epidemiology research of recent years. There is now increasing evidence that alterations in the fetal environment have long-term consequences on metabolic and endocrine pathophysiology in adult life. This process has been termed "fetal programming," and we have shown that undernutrition of the mother during gestation leads to obesity, hypertension, hyperphagia, hyperinsulinemia, and hyperleptinemia in offspring. Using this model of maternal undernutrition throughout pregnancy, we investigated whether prenatal influences may lead to alterations in postnatal locomotor behavior, independent of postnatal nutrition. Virgin Wistar rats were time mated and randomly assigned to receive food either ad libitum (ad libitum group) or at 30% of ad libitum intake (undernourished group). Offspring from UN mothers were significantly smaller at birth than AD offspring. At weaning, offspring were assigned to one of two diets [control or hypercaloric (30% fat)]. At ages of 35 days, 145 days, and 420 days, voluntary locomotor activity was assessed. At all ages studied, offspring from undernourished mothers were significantly less active than offspring born of normal birth weight for all parameters measured, independent of postnatal nutrition. Sedentary behavior in programmed offspring was exacerbated by postnatal hypercaloric nutrition. This work is the first to clearly separate prenatal from postnatal effects and shows that lifestyle choices themselves may have a prenatal origin. We have shown that predispositions to obesity, altered eating behavior, and sedentary activity are linked and occur independently of postnatal hypercaloric nutrition. Moreover, the prenatal influence may be permanent as offspring of undernourished mothers were still significantly less active compared with normal offspring at an advanced adult age, even in the presence of a healthy diet throughout postnatal life.     

Offspring metabolomic response to maternal protein restriction in a rat model of intrauterine growth restriction (IUGR)

Intrauterine growth restriction (IUGR), along with postnatal growth trajectory, is closely linked with metabolic diseases and obesity at adulthood. The present study reports the time-dependent metabolomic response of male offspring of rat dams exposed to maternal adequate protein diet during pregnancy and lactation (CC) or protein deprivation during pregnancy only (IUGR with rapid catch-up growth, RC) or through pregnancy and lactation (IUGR with slow postnatal growth, RR). Plasma LC-HRMS metabolomic fingerprints for 8 male rats per group, combined with multivariate statistical analysis (PLS-DA and HCA), were used to study the impact of IUGR and postnatal growth velocity on the offspring metabolism in early life (until weaning) and once they reached adulthood (8 months). Compared with CC rats, RR pups had clear-cut alterations in plasma metabolome during suckling, but none at adulthood; in contrast, in RC pups, alterations in metabolome were minimal in early life but more pronounced in the long run. In particular, our results pinpoint transient alterations in proline, arginine, and histidine in RR rats, compared to CC rats, and persistent differences in tyrosine and carnitine, compared to RC rats at adulthood. These findings suggest that the long-term deregulation in feeding behavior and fatty acid metabolism in IUGR rats depends on postnatal growth velocity.     

Long term effects of prenatal cocaine exposure on bone in rats

Prenatal exposure to cocaine has been shown to produce a variety of effects on skeletal development and mineralization in humans, mice, and rats. The effects of cocaine on bone cell function and mineral metabolism pre- and postnatally are poorly understood. The present study examined the long term effects of prenatal cocaine exposure on femoral growth and mineralization in male rats. Pregnant rats were given 80 or 100 mg cocaine hydrochloride/kg during days 7-20 of gestation. At birth, body weights of pups born to these females were significantly decreased compared to normal and pair-fed controls. At the termination of the study (32 weeks), body weights of offspring from C100-treated females were still lower than normal. Long term effects of prenatal exposure to cocaine on femoral growth were most pronounced in offspring of C80-treated females. Femur dry weight, ash weight, organic matrix weight and density were significantly reduced in these animals compared to normal or pair-fed controls. The apparent osteopenic effects of prenatal exposure to cocaine suggests some long term postnatal impact on bone cell or mineral metabolism. Previous studies of cocaine use during pregnancy in humans and animals have focused primarily on physical and behavioral defects in offspring. The present findings indicate that prenatal exposure to cocaine may also have long term consequences to the skeleton.     

Prenatal Exposure to Nicotine Causes Postnatal Obesity and Altered Perivascular Adipose Tissue Function

Objective: Recent epidemiological studies have shown that there is an increased risk of obesity and hypertension in children born to women who smoked during pregnancy. The aim of this study was to examine the effect of fetal and neonatal exposure to nicotine, the major addictive component of cigarette smoke, on postnatal adiposity and blood vessel function. Research Methods and Procedures: Female Wistar rats were given nicotine or saline (vehicle) during pregnancy and lactation. Postnatal growth was determined in the male offspring from weaning until 26 weeks of age. At 26 weeks of age, fat pad weight and the function of the perivascular adipose tissue (PVAT) in the thoracic aorta and mesenteric arteries were examined. Results: Exposure to nicotine resulted in increased postnatal body weight and fat pad weight and an increased amount of PVAT in the offspring. Contraction of the aorta induced by phenylephrine was significantly attenuated in the presence of PVAT, whereas this effect was not observed in the aortic rings from the offspring of nicotine‐exposed dams. Phenylephrine‐induced contraction without PVAT was not different between saline‐ and nicotine‐exposed rats. Transfer of solution incubated with PVAT‐intact aorta to PVAT‐free aorta induced a marked relaxation response in the rats from saline‐exposed dams, but this relaxation response was significantly impaired in the rats from nicotine‐exposed dams. Discussion: Our results showed that prenatal nicotine exposure increased adiposity and caused an alteration in the modulatory function of PVAT on vascular relaxation response, thus providing insight into the mechanisms underlying the increased prevalence of obesity and hypertension in children exposed to cigarette smoke in utero.     

Multiple exposures to environmental pollutants and oxidative stress: Is there a sex specific risk of developmental complications for fetuses?

Medically assisted procreation significantly contributes to an increase in twin pregnancies. One of the major factors contributing to more twin births is the use of fertility treatments. Twin pregnancy is not without a risk for fetal organ development and the health outcome of new‐borns, children, and adults. Multiple pregnancies are associated with an increased risk of developmental complications, such as perinatal mortality, premature births, and low birth weight. Oxidative stress is involved in pregnancy disorders such as abortion, intrauterine growth retardation, and prenatal mortality. The link between oxidative stress and prenatal development, poorly perceived in the medical community, is a major problem in human reproductive medicine and health outcomes. The sex‐based considerations and analyses are also, often neglected in biomedical research. In addition, fetal sexual dimorphism in antioxidant pathways following intrauterine exposure to environmental pollutants has not been explored. This is an important area of research because sexually dimorphic antioxidant adaptive responses to early life exposure‐induced oxidative stress may have long‐term effects on offspring health outcome and increase the risk of non‐communicable diseases in men and women. This concept is useful, since it may open the avenue to develop antenatal antioxidant therapeutic strategies to developmental disorders and complications related to multiple pregnancies, and in association with acute or chronic environmental exposure. This article reviews the status of research, supporting data, possible pathogenic mechanisms, and future perspectives in the proposed area. Birth Defects Research (Part C) 108:351–364, 2016. © 2016 Wiley Periodicals, Inc.     

Impact of Low Dose Prenatal Ethanol Exposure on Glucose Homeostasis in Sprague-Dawley Rats Aged up to Eight Months

Excessive exposure to alcohol prenatally has a myriad of detrimental effects on the health and well-being of the offspring. It is unknown whether chronic low-moderate exposure of alcohol prenatally has similar and lasting effects on the adult offspring’s health. Using our recently developed Sprague-Dawley rat model of 6% chronic prenatal ethanol exposure, this study aimed to determine if this modest level of exposure adversely affects glucose homeostasis in male and female offspring aged up to eight months. Plasma glucose concentrations were measured in late fetal and postnatal life. The pancreas of 30 day old offspring was analysed for β-cell mass. Glucose handling and insulin action was measured at four months using an intraperitoneal glucose tolerance test and insulin challenge, respectively. Body composition and metabolic gene expression were measured at eight months. Despite normoglycaemia in ethanol consuming dams, ethanol-exposed fetuses were hypoglycaemic at embryonic day 20. Ethanol-exposed offspring were normoglycaemic and normoinsulinaemic under basal fasting conditions and had normal pancreatic β-cell mass at postnatal day 30. However, during a glucose tolerance test, male ethanol-exposed offspring were hyperinsulinaemic with increased first phase insulin secretion. Female ethanol-exposed offspring displayed enhanced glucose clearance during an insulin challenge. Body composition and hepatic, muscle and adipose tissue metabolic gene expression levels at eight months were not altered by prenatal ethanol exposure. Low-moderate chronic prenatal ethanol exposure has subtle, sex specific effects on glucose homeostasis in the young adult rat. As aging is associated with glucose dysregulation, further studies will clarify the long lasting effects of prenatal ethanol exposure.