Exposure to undernutrition in fetal life determines fat distribution, locomotor activity and food intake in ageing rats

Effects of dietary protein level on nutrients digestibility and reproductive performance of female mink (Neovison vison) during gestation

The objective of this study was to determine whether nutrient digestibility and reproductive performance of pregnant mink (Neovison vison) were affected by different dietary protein levels. One hundred and twenty female mink were randomly assigned to four groups, receiving diets of fresh material with different protein levels. The dietary protein levels, expressed as percentage of dry matter (DM), were 32, 36, 40 and 44% respectively. These values corresponded to average 320, 360, 400 and 440 g protein/kg DM, respectively. Results were as follows. All of crude protein digestibility, nitrogen (N) intake, N retention increased along with dietary protein level increasing. Low protein level (32%) significantly reduced the above indicators (P < 0.05). DM digestibility and ether extract digestibility were not affected by dietary protein level. Results of mated females, barren females, kids per litter, live born kids per mated female, birth survival rate, and birth weight showed that mink achieved optimal reproductive performance when dietary protein level was 36%. In conclusion, dietary protein was anticipated to significantly influence some nutrients' utilization. Adopting the appropriate dietary protein level allow better reproduction performance. The most preferable reproductive performance was achieved when diet contained 275.5 g digestible protein per kg DM for female mink in gestation.

Association between birth weight and objectively measured sedentary time is mediated by central adiposity: data in 10,793 youth from the International Children's Accelerometry Database

BACKGROUND

Birth weight is an early correlate of disease later in life, and animal studies suggest that low birth weight is associated with reduced activity and increased sedentary time. Whether birth weight predicts later sedentary time in humans is uncertain.

OBJECTIVES

We examined the relation between birth weight and sedentary time in youth and examined whether this association was mediated by central adiposity.

DESIGN

We used pooled cross-sectional data from 8 observational studies conducted between 1997 and 2007 that consisted of 10,793 youth (boys: 47%) aged 6-18 y from the International Children's Accelerometry Database. Birth weight was measured in hospitals or maternally reported, sedentary time was assessed by using accelerometry (<100 counts/min), and abdominal adiposity (waist circumference) was measured according to WHO procedures. A mediation analysis with bootstrapping was used to analyze data.

RESULTS

The mean (±SD) time spent sedentary was 370 ± 91 min/d. Birth weight was positively associated with sedentary time (B = 4.04, P = 0.006) and waist circumference (B = 1.59, P < 0.001), whereas waist circumference was positively associated with sedentary time (B = 0.82, P < 0.001). Results of the mediation analysis showed a significant indirect effect of birth weight on sedentary time through waist circumference (B: 1.30; 95% bias-corrected CI: 0.94, 1.72), and when waist circumference was controlled for, the effect of birth weight on sedentary time was attenuated by 32% (B = 2.74, P = 0.06).

CONCLUSION

The association between birth weight and sedentary time appears partially mediated by central adiposity, suggesting that both birth weight and abdominal adiposity may be correlates of sedentary time in youth.

Perinatal malnutrition stimulates motivation through reward and enhances drd(1a) receptor expression in the ventral striatum of adult mice

AIM

The aim of this study was to analyze the effects of protein perinatal malnutrition on the function of dopamine DRD1 and DRD2 receptors in regards to motivation and food consumption in adult mice. The study also analyzed the effect of protein perinatal malnutrition on the gene expression of these receptors in the ventral striatum.

METHODS

Wistar lineage mice were divided into two groups according to maternal diet: control (17% casein), n=30 and low protein (8% casein), n=30. Between 30 and 120days of life, the following factors were measured: body weight; the effect of dopamine D1 and D2 agonists on the ingestion of palatable food; the motivational aspect under the action of the D1 (SKF 38393) and D2 Quinpirole dopaminergic agonists; and the gene expression of DRD1 and DRD2 receptors in the ventral striatum.

RESULTS

The body weights of the malnourished animals remained significantly lower than those of the control group from 30 to 120days of life. Malnourished animals ingested a greater quantity of palatable food. There was a decrease in palatable diet consumption in both the control and malnourished groups after the application of D1 and D2 agonists; however, the anorexic effect of the D1 agonist was understated in malnourished animals. Perinatal malnutrition increases the motivational behavior of the animal when food reward is used. There was an increase in gene expression of the DRD1a receptor in the ventral striatum of malnourished animals, and there were no significant changes concerning the DRD2 receptor.

CONCLUSIONS

Perinatal protein malnutrition stimulates hedonic control of eating behavior by promoting increased intake of palatable foods, possibly due to increased expression of dopamine receptor DRD1a in the ventral striatum.

Maternal diet as a modifier of offspring epigenetics

There has been a substantial body of evidence, which has shown that genetic variation is an important determinant of disease risk. However, there is now increasing evidence that alterations in epigenetic processes also play a role in determining susceptibility to disease. Epigenetic processes, which include DNA methylation, histone modifications and non-coding RNAs play a central role in regulating gene expression, determining when and where a gene is expressed as well as the level of gene expression. The epigenome is highly sensitive to a variety of environmental factors, especially in early life. One factor that has been shown consistently to alter the epigenome is maternal diet. This review will focus on how maternal diet can modify the epigenome of the offspring, producing different phenotypes and altered disease susceptibilities.

Increased palatable food intake and response to food cues in intrauterine growth-restricted rats are related to tyrosine hydroxylase content in the orbitofrontal cortex and nucleus accumbens

Intrauterine growth restriction (IUGR) is associated with altered food preferences, which may contribute to increased risk of obesity. We evaluated the effects of IUGR on attention to a palatable food cue, as well as tyrosine hydroxylase (TH) content in the orbitofrontal cortex (OFC) and nucleus accumbens (NAcc) in response to sweet food intake. From day 10 of gestation and through lactation, Sprague-Dawley rats received either an ad libitum (Adlib) or a 50% food-restricted (FR) diet. At birth, pups were cross-fostered, generating four groups (gestation/lactation): Adlib/Adlib (control), FR/Adlib (intrauterine growth-restricted), Adlib/FR, and FR/FR. Adult attention to palatable food cues was measured using the Attentional Set-Shifting Task (ASST), which uses a sweet pellet as reward. TH content in the OFC and NAcc was measured at baseline and in response to palatable food intake. At 90 days of age, FR/Adlib males ate more sweet food than controls, without differences in females. However, when compared to Controls, FR/Adlib females needed fewer trials to reach criterion in the ASST (p=0.04) and exhibited increased TH content in the OFC in response to sweet food (p=0.03). In the NAcc, there was a differential response of TH content after sweet food intake in both FR/Adlib males and females (p<0.05). Fetal programming of adult food preferences involves the central response to palatable food cues and intake, affecting dopamine release in select structures of the brain reward system.

Leptin intake in suckling rats restores altered T3 levels and markers of adipose tissue sympathetic drive and function caused by gestational calorie restriction

BACKGROUND

Maternal calorie restriction during gestation in rats has been associated with altered white adipose tissue (WAT) sympathetic innervation and function in offspring. Here, we aimed to investigate whether supplementation with oral leptin (a breast milk component) throughout the lactation period may revert the aforementioned adverse programming effects.

METHODS

Three groups of male and female rats were studied at the postnatal day 25: the offspring of control dams, the offspring of 20% calorie-restricted dams during pregnancy (CR) and CR rats supplemented with physiological doses of leptin throughout lactation (CR-Leptin). Tyrosine hydroxylase (TH) levels and its immunoreactive area, and mRNA expression levels of lipid metabolism-related genes and of deiodinase iodothyronine type II (Dio2) were determined in WAT. Triiodothyronine (T3) levels were determined in the blood.

RESULTS

In CR males, leptin treatment restored the decreased TH levels and its immunoreactive area in WAT, and partially normalized expression levels of genes related to lipolysis and fatty acid oxidation (adipose triglyceride lipase, hormone-sensitive lipase, carnitine palmitoyltransferase 1b and peroxisome proliferator-activated receptor gamma coactivator 1-alpha). Leptin treatment also reverted the decreased T3 plasma levels and WAT lipoprotein lipase mRNA levels occurring in CR males and females, and the decreased Dio2 mRNA levels in CR females.

CONCLUSIONS

Leptin supplementation throughout the lactation period reverts the malprogrammed effects on WAT structure and function induced by undernutrition during pregnancy. These findings support the relevance of the intake of leptin during lactation, bearing clear characteristics of essential nutrient, and provide a strategy to treat and/or prevent the programmed trend to obesity acquired by inadequate fetal nutrition.

Offspring subcutaneous adipose markers are sensitive to the timing of maternal gestational weight gain

BACKGROUND

Excessive maternal weight gain during pregnancy impacts on offspring health. This study focused on the timing of maternal gestational weight gain, using a porcine model with mothers of normal pre-pregnancy weight.

METHODS

Trial design ensured the trajectory of maternal gestational weight gain differed across treatments in early, mid and late gestation. Diet composition did not differ. On day 25 gestation, sows were assigned to one of five treatments: Control sows received a standard gestation diet of 2.3 kg/day (30 MJ DE/day) from early to late gestation (day 25-110 gestation). E sows received 4.6 kg food/day in early gestation (day 25-50 gestation). M sows doubled their food intake in mid gestation (day 50-80 gestation). EM sows doubled their food intake during both early and mid gestation (day 25-80 gestation). L sows consumed 3.5 kg food/day in late gestation (day 80-110 gestation). Offspring body weight and food intake levels were measured from birth to adolescence. Markers of lipid metabolism, hypertrophy and inflammation were investigated in subcutaneous adipose tissue of adolescent offspring.

RESULTS

The trajectory of gestational weight gain differed across treatments. However total gestational weight gain did not differ except for EM sows who were the heaviest and fattest mothers at parturition. Offspring birth weight did not differ across treatments. Subcutaneous adipose tissue from EM offspring differed significantly from controls, with elevated mRNA levels of lipogenic (CD36, ACACB and LPL), nutrient transporters (FABP4 and GLUT4), lipolysis (HSL and ATGL), adipocyte size (MEST) and inflammation (PAI-1) indicators. The subcutaneous adipose depot from L offspring exhibited elevated levels of CD36, ACACB, LPL, GLUT4 and FABP4 mRNA transcripts compared to control offspring.

CONCLUSIONS

Increasing gestational weight gain in early gestation had the greatest impact on offspring postnatal growth rate. Increasing maternal food allowance in late gestation appeared to shift the offspring adipocyte focus towards accumulation of fat. Mothers who gained the most weight during gestation (EM mothers) gave birth to offspring whose subcutaneous adipose tissue, at adolescence, appeared hyperactive compared to controls. This study concluded that mothers, who gained more than the recommended weight gain in mid and late gestation, put their offspring adipose tissue at risk of dysfunction.

Body composition and behaviour in adult rats are influenced by maternal diet, maternal age and high-fat feeding

Fetal exposure to maternal undernutrition has lifelong consequences for physiological and metabolic function. Maternal low-protein diet is associated with an age-related phenotype in rats, characterised by a period of resistance to development of obesity in early adulthood, giving way to an obesity-prone, insulin-resistant state in later adulthood. Offspring of rats fed a control (18 % casein) or low-protein (9 % casein; LP) diet in pregnancy were challenged with a high-fat diet at 9 months of age. To assess whether other maternal factors modulated the programming effects of nutrition, offspring were studied from young (2–4 months old) and older (6–9 months old) mothers. Weight gain with a high-fat diet was attenuated in male offspring of older mothers fed LP (interaction of maternal age and diet; P = 0·011) and adipose tissue deposition was lower with LP feeding in both males and females (P < 0·05). Although the resistance to weight gain and adiposity was partially explained by lower energy intake in offspring of LP mothers (P < 0·001 males only), it was apparent that energy expenditure must be influenced by maternal diet and age. Assessment of locomotor activity indicated that energy expenditure associated with physical activity was unlikely to explain resistance to weight gain, but showed that offspring of older mothers were more anxious than those of younger mothers, with more rearing observed in a novel environment and on the elevated plus-maze. The data showed that in addition to maternal undernutrition, greater maternal age may influence development and long-term body composition in the rat.

Developmental programming of cardiovascular disease following intrauterine growth restriction: findings utilising a rat model of maternal protein restriction

Over recent years, studies have demonstrated links between risk of cardiovascular disease in adulthood and adverse events that occurred very early in life during fetal development. The concept that there are embryonic and fetal adaptive responses to a sub-optimal intrauterine environment often brought about by poor maternal diet that result in permanent adverse consequences to life-long health is consistent with the definition of "programming". The purpose of this review is to provide an overview of the current knowledge of the effects of intrauterine growth restriction (IUGR) on long-term cardiac structure and function, with particular emphasis on the effects of maternal protein restriction. Much of our recent knowledge has been derived from animal models. We review the current literature of one of the most commonly used models of IUGR (maternal protein restriction in rats), in relation to birth weight and postnatal growth, blood pressure and cardiac structure and function. In doing so, we highlight the complexity of developmental programming, with regards to timing, degree of severity of the insult, genotype and the subsequent postnatal phenotype.

Proteinuria in aging rats due to low-protein diet during mid-gestation

Nephrogenesis in the rat starts mid-gestation and continues into lactation. Maternal low protein (LP) intake leads to renal injury in rats and associates with mild renal injury in humans. We hypothesized that LP during early nephrogenesis or throughout gestation would induce more renal injury in rat offspring than when LP was only present before nephrogenesis. Pregnant rats were fed LP diet (9% casein) at early gestation (LPE, day 0-7), mid (LPM, day 8-14), late (LPL, day 15-22) or throughout gestation (LPA, day 0-22) and compared to controls on 18% casein diet. Offspring were studied at 18 months. Renal injury was assessed by 24 h proteinuria, plasma urea, antioxidant enzyme activities, and apoptosis (Bax/Bcl2). Proteinuria was higher in LPM males and LPE and LPM females. In LPM males glutathione peroxidase activity was lower, while in LPE males catalase activity was higher. Antioxidants were not much affected in females. Bax expression was higher in LPM males and females, while Bcl2 expression was higher in LPA females. Thus even before nephrogenesis (day 0-7), LP impacted on renal integrity in adult life, while LP during a later phase (day 15-22) or throughout gestation had less effect. In summary, for aging rat kidney LP poses the greatest threat when restricted to early nephrogenesis.

Maternal undernutrition and fetal developmental programming of obesity: the glucocorticoid connection

An adequate maternal nutrition during pregnancy is crucial for the health outcome of offspring in adulthood. Maternal undernutrition during critical periods of fetal development can program the fetus for metabolic syndrome (MetS) later in life, especially when postnatally challenged with a hypernutritive diet. Adipogenesis, which begins in utero and accelerates in neonatal life, is a major candidate for developmental programming. During fetal development, the hypothalamic-pituitary-adrenal (HPA) axis is extremely susceptible to programming, and the HPA tone is increased throughout life in undernourished conditions. As a consequence, an alteration in the expression and function of glucocorticoid (GC) receptors and of the major GC regulatory enzymes (11β-hydroxysteroid dehydrogenase 1 and -2) occurs. In this review, we will give insights into the role of maternoplacental adverse interactions under the specific context of maternal undernutrition, for later-in-life MetS development, with a special emphasis on the role of GCs.

Epigenetic inheritance of metabolic state

As the incidence of complex metabolic disease increases in developed countries, so too does the need to understand the causes and risk factors for these disorders. In addition to the well-known contribution of genetics and environment to metabolic dysfunction, many studies have demonstrated that a significant degree of non-genetic heritable risk can be transmitted from parents to offspring over multiple generations. Understanding the mechanisms by which this occurs could change how we study and treat complex metabolic disorders. In this review, we summarize recent advances in this field utilizing Drosophila, mice, and humans, and propose potential molecular mechanisms that underlie the transgenerational inheritance of metabolic state.

Epigenetic mechanisms affecting regulation of energy balance: many questions, few answers

Extensive human and animal model data show that nutrition and other environmental influences during critical periods of embryonic, fetal, and early postnatal life can affect the development of body weight regulatory pathways, with permanent consequences for risk of obesity. Epigenetic processes are widely viewed as a leading mechanism to explain the lifelong persistence of such "developmental programming" of energy balance. Despite meaningful progress in recent years, however, significant research obstacles impede our ability to test this hypothesis. Accordingly, this review attempts to summarize progress toward answering the following outstanding questions: Is epigenetic dysregulation a major cause of human obesity? In what cells/tissues is epigenetic regulation most important for energy balance? Does developmental programming of human body weight regulation occur via epigenetic mechanisms? Do epigenetic mechanisms have a greater impact on food intake or energy expenditure? Does epigenetic inheritance contribute to transgenerational patterns of obesity? In each case, significant obstacles and suggested approaches to surmounting them are elaborated.

Effect of maternal protein restriction during pregnancy and postweaning high-fat feeding on diet-induced thermogenesis in adult mouse offspring

PURPOSE

Prenatal undernutrition followed by postweaning feeding of a high-fat diet results in obesity in the adult offspring. In this study, we investigated whether diet-induced thermogenesis is altered as a result of such nutritional mismatch.

METHODS

Female MF-1 mice were fed a normal protein (NP, 18% casein) or a protein-restricted (PR, 9% casein) diet throughout pregnancy and lactation. After weaning, male offspring of both groups were fed either a high-fat diet (HF; 45% kcal fat) or standard chow (C, 7% kcal fat) to generate the NP/C, NP/HF, PR/C and PR/HF adult offspring groups (n = 7-11 per group).

RESULTS

PR/C and NP/C offspring have similar body weights at 30 weeks of age. Postweaning HF feeding resulted in significantly heavier NP/HF offspring (P < 0.01), but not in PR/HF offspring, compared with their chow-fed counterparts. However, the PR/HF offspring exhibited greater adiposity (P < 0.01) v the NP/HF group. The NP/HF offspring had increased energy expenditure and increased mRNA expression of uncoupling protein-1 and β-3 adrenergic receptor in the interscapular brown adipose tissue (iBAT) compared with the NP/C mice (both at P < 0.01). No such differences in energy expenditure and iBAT gene expression were observed between the PR/HF and PR/C offspring.

CONCLUSIONS

These data suggest that a mismatch between maternal diet during pregnancy and lactation, and the postweaning diet of the offspring, can attenuate diet-induced thermogenesis in the iBAT, resulting in the development of obesity in adulthood.

Genome-wide methylation and gene expression changes in newborn rats following maternal protein restriction and reversal by folic acid

A large body of evidence from human and animal studies demonstrates that the maternal diet during pregnancy can programme physiological and metabolic functions in the developing fetus, effectively determining susceptibility to later disease. The mechanistic basis of such programming is unclear but may involve resetting of epigenetic marks and fetal gene expression. The aim of this study was to evaluate genome-wide DNA methylation and gene expression in the livers of newborn rats exposed to maternal protein restriction. On day one postnatally, there were 618 differentially expressed genes and 1183 differentially methylated regions (FDR 5%). The functional analysis of differentially expressed genes indicated a significant effect on DNA repair/cycle/maintenance functions and of lipid, amino acid metabolism and circadian functions. Enrichment for known biological functions was found to be associated with differentially methylated regions. Moreover, these epigenetically altered regions overlapped genetic loci associated with metabolic and cardiovascular diseases. Both expression changes and DNA methylation changes were largely reversed by supplementing the protein restricted diet with folic acid. Although the epigenetic and gene expression signatures appeared to underpin largely different biological processes, the gene expression profile of DNA methyl transferases was altered, providing a potential link between the two molecular signatures. The data showed that maternal protein restriction is associated with widespread differential gene expression and DNA methylation across the genome, and that folic acid is able to reset both molecular signatures.

Fetal growth restriction promotes physical inactivity and obesity in female mice

BACKGROUND

Environmental exposures during critical periods of prenatal and early postnatal life affect the development of mammalian body weight regulatory mechanisms, influencing lifelong risk of obesity. The specific biological processes that mediate the persistence of such effects, however, remain poorly understood.

OBJECTIVE

The objectives of this study were to determine the developmental timing and physiological basis of the obesity-promoting effect previously reported in offspring of obese agouti viable yellow (A(vy)/a) mothers.

DESIGN

Newborn offspring of obese A(vy)/a and lean (a/a) mothers were cross-fostered shortly after birth to study separately the effects of in utero or suckling period exposure to A(vy)/a dams. Body composition, food intake, physical activity and energy expenditure were measured in offspring shortly after weaning and in adulthood.

RESULTS

Offspring of obese A(vy)/a dams paradoxically experienced fetal growth restriction, which was followed by adult-onset obesity specifically in females. Our main analyses focused on wild-type (a/a) offspring, because a subset of adult A(vy)/a offspring contracted a kidney disease resembling diabetic nephropathy. Detailed physiological characterization demonstrated that, both shortly after weaning and in adulthood, female wild-type mice born to A(vy)/a mothers are not hyperphagic but have reduced physical activity and energy expenditure. No such coordinated changes were detected in male offspring. Mediational regression analysis of our longitudinal data supported a causal pathway in which fetal growth restriction persistently reduces physical activity, leading to adult obesity.

CONCLUSIONS

Our data are consistent with several recent human epidemiological studies showing female-specific effects of perinatal nutritional restriction on later obesity, and provide the novel mechanistic insight that this may occur via permanent and sex-specific changes in one's inherent propensity for physical activity.

Study protocol: the relation of birth weight and infant growth trajectories with physical fitness, physical activity and sedentary behavior at 8-9 years of age - the ABCD study

BACKGROUND

Low birth weight and accelerated infant growth have been identified as independent risk factors for childhood and adult obesity and cardiovascular disease. This led to the 'Developmental Origins of Health and Disease' (DOHaD) hypothesis, stating that environmental factors during pregnancy and early postnatal life affect disease risk in later life. There is growing evidence that perinatal factors may influence adult health through the programming of energy balance regulation, including sedentary behavior and physical activity. The present study focuses on the influence of birth weight and infant growth on physical fitness, physical activity and sedentary behavior in 8-9 year old children, as this might partly explain the higher obesity and cardiovascular risk associated with low birth weight and accelerated infant growth. In addition, this study provides the opportunity for a validation study of a linguistic and cross-cultural translated physical activity questionnaire compared to accelerometer data. This article describes the study protocol for this study.

METHODS/DESIGN

This is a study embedded in the Amsterdam Born Children and their Development (ABCD) birth cohort. In 200 children of Dutch ethnicity, physical fitness, physical activity and sedentary behavior were assessed at age 8-9. We measured aerobic fitness using the 20 meter multistage shuttle run test, and neuromuscular fitness using the standing broad jump and handgrip strength test. Sedentary behavior and physical activity levels were measured using accelerometry. All children also completed a translated physical activity questionnaire, the scores of which will be compared to accelerometry data to assess the construct validity of the questionnaire in Dutch school-aged children.

DISCUSSION

This study will be the first population-based prospective cohort study to address the association of both prenatal and postnatal growth with physical fitness and objectively-assessed physical activity and sedentary behavior. This will contribute to a better understanding of the way perinatal growth relate to lifestyle and obesity in later life. The results may guide both future studies in the field of DOHaD, and public health strategies in the prevention of childhood obesity.

Intergenerational programming of metabolic disease: evidence from human populations and experimental animal models

We are in the midst of unparalleled epidemics of obesity and type 2 diabetes-complex phenotypes originating at the intersection of genetic and environmental risk. As detailed in other chapters, evidence indicates that non-genetic, or environmental, risk may initiate during prenatal and early postnatal life [1]. Striking examples in humans include the association of low birth weight (LBW) and/or accelerated early growth with increased risk of insulin resistance, obesity, type 2 diabetes (T2DM), and cardiovascular disease (CVD), and the close relationship between maternal obesity or diabetes with childhood obesity. In this chapter, we will focus on the intriguing emerging data from both human and animal models that indicate that intrauterine and childhood exposures can also influence risk for diabetes and cardiovascular disease in subsequent generations. Understanding the mechanisms responsible for these effects is critical in order to develop effective metabolic and nutritional interventions to interrupt such vicious intergenerational cycles potentiating risk for metabolic disorders.

Influence of maternal low protein diet during pregnancy on hepatic gene expression signature in juvenile female porcine offspring

SCOPE

Epidemiological and experimental evidence indicates that maternal nutrition status contributes to long-term changes in the metabolic phenotype of the offspring, a process known as fetal programming.

METHODS AND RESULTS

We have used a swine model (Sus scrofa) to analyze consequences of a maternal low protein diet (about 50% of control) during pregnancy on hepatic lipid metabolism and genome-wide hepatic gene expression profile of juvenile female offspring (mean age 85 days). We found 318 S. scrofa genes to be differentially expressed in the liver at age 85 days. In the low protein offspring group key genes of fatty acid de novo synthesis were downregulated whereas several genes of lipolysis and phospholipid biosynthesis were upregulated. qRT-PCR analysis of selected genes verified microarray data and revealed linear correlations between gene expression levels and slaughter weight. Hepatic cholesterol 7α hydroxylase protein expression tended to be lower in the low protein group. Total lipid and triglyceride content and fatty acid composition of total lipids were not different between groups.

CONCLUSION

A maternal low protein diet during pregnancy induces a distinct hepatic gene expression signature in juvenile female pigs which was not translated into phenotypical changes of liver lipid metabolism.

Behavior genetics and postgenomics

The science of genetics is undergoing a paradigm shift. Recent discoveries, including the activity of retrotransposons, the extent of copy number variations, somatic and chromosomal mosaicism, and the nature of the epigenome as a regulator of DNA expressivity, are challenging a series of dogmas concerning the nature of the genome and the relationship between genotype and phenotype. According to three widely held dogmas, DNA is the unchanging template of heredity, is identical in all the cells and tissues of the body, and is the sole agent of inheritance. Rather than being an unchanging template, DNA appears subject to a good deal of environmentally induced change. Instead of identical DNA in all the cells of the body, somatic mosaicism appears to be the normal human condition. And DNA can no longer be considered the sole agent of inheritance. We now know that the epigenome, which regulates gene expressivity, can be inherited via the germline. These developments are particularly significant for behavior genetics for at least three reasons: First, epigenetic regulation, DNA variability, and somatic mosaicism appear to be particularly prevalent in the human brain and probably are involved in much of human behavior; second, they have important implications for the validity of heritability and gene association studies, the methodologies that largely define the discipline of behavior genetics; and third, they appear to play a critical role in development during the perinatal period and, in particular, in enabling phenotypic plasticity in offspring. I examine one of the central claims to emerge from the use of heritability studies in the behavioral sciences, the principle of minimal shared maternal effects, in light of the growing awareness that the maternal perinatal environment is a critical venue for the exercise of adaptive phenotypic plasticity. This consideration has important implications for both developmental and evolutionary biology.

Late gestation undernutrition can predispose for visceral adiposity by altering fat distribution patterns and increasing the preference for a high-fat diet in early postnatal life

We have developed a sheep model to facilitate studies of the fetal programming effects of mismatched perinatal and postnatal nutrition. During the last trimester of gestation, twenty-one twin-bearing ewes were fed a normal diet fulfilling norms for energy and protein (NORM) or 50 % of a normal diet (LOW). From day 3 postpartum to 6 months (around puberty) of age, one twin lamb was fed a conventional (CONV) diet and the other a high-carbohydrate–high-fat (HCHF) diet, resulting in four groups of offspring: NORM-CONV; NORM-HCHF; LOW-CONV; LOW-HCHF. At 6 months of age, half of the lambs (all males and three females) were slaughtered for further examination and the other half (females only) were transferred to a moderate sheep diet until slaughtered at 24 months of age (adulthood). Maternal undernutrition during late gestation reduced the birth weight of LOW offspring (P< 0·05), and its long-term effects were increased adrenal size in male lambs and adult females (P< 0·05), increased neonatal appetite for fat-(P= 0·004) rather than carbohydrate-rich feeds (P< 0·001) and reduced deposition of subcutaneous fat in both sexes (P< 0·05). Furthermore, LOW-HCHF female lambs had markedly higher visceral:subcutaneous fat ratios compared with the other groups (P< 0·001). Postnatal overfeeding (HCHF) resulted in obesity (>30 % fat in soft tissue) and widespread ectopic lipid deposition. In conclusion, our sheep model revealed strong pre- and postnatal impacts on growth, food preferences and fat deposition patterns. The present findings support a role for subcutaneous adipose tissue in the development of visceral adiposity, which in humans is known to precede the development of the metabolic syndrome in human adults.

Epigenetic mechanisms linking early nutrition to long term health

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

Effect of food restriction and leptin supplementation on fetal programming in mice

Metabolic disease is a significant global health and economic problem. In a phenomenon referred to as fetal programming, offspring of underweight or overweight mothers have an increased incidence of adulthood obesity and metabolic disease. Undernourished individuals have decreased levels of leptin, a regulator of energy balance, whereas obese people develop hyperleptinemia and leptin resistance. We hypothesize that alterations in circulating leptin during pregnancy contribute to programming events caused by maternal nutritional status. To test this hypothesis, pregnant mice were randomly placed in one of three treatment groups: ad libitum feed plus saline injection (control, n = 5), 50% food restriction plus saline injection (restricted, n = 4), or 50% food restriction plus 1 mg/kg · d leptin injection (restricted, leptin treated, n = 4). Mice were treated from 1.5 to 11.5 d after conception and then returned to ad libitum feeding until weaning. At 19 wk after weaning, offspring were placed on a 45% fat diet and then followed up until 26 wk after weaning, at which time they were killed, and samples were collected for further analysis. Our results demonstrate that males are more negatively impacted by high-fat diet than females, regardless of maternal treatment. We provide evidence that differential response to leptin may mediate the sexual dimorphism observed in fetal programming in which male offspring are more affected by maternal undernutrition and female offspring by maternal overnutrition. We show that female offspring born to food-restricted, leptin-supplemented mothers are obese and insulin resistant. This may mimic fetal programming events seen in offspring of overweight women.

The suckling rat as a model for immunonutrition studies in early life

Diet plays a crucial role in maintaining optimal immune function. Research demonstrates the immunomodulatory properties and mechanisms of particular nutrients; however, these aspects are studied less in early life, when diet may exert an important role in the immune development of the neonate. Besides the limited data from epidemiological and human interventional trials in early life, animal models hold the key to increase the current knowledge about this interaction in this particular period. This paper reports the potential of the suckling rat as a model for immunonutrition studies in early life. In particular, it describes the main changes in the systemic and mucosal immune system development during rat suckling and allows some of these elements to be established as target biomarkers for studying the influence of particular nutrients. Different approaches to evaluate these immune effects, including the manipulation of the maternal diet during gestation and/or lactation or feeding the nutrient directly to the pups, are also described in detail. In summary, this paper provides investigators with useful tools for better designing experimental approaches focused on nutrition in early life for programming and immune development by using the suckling rat as a model.

Strategies for reversing the effects of metabolic disorders induced as a consequence of developmental programming

Obesity and the metabolic syndrome have reached epidemic proportions worldwide with far-reaching health care and economic implications. The rapid increase in the prevalence of these disorders suggests that environmental and behavioral influences, rather than genetic causes, are fueling the epidemic. The developmental origins of health and disease hypothesis has highlighted the link between the periconceptual, fetal, and early infant phases of life and the subsequent development of metabolic disorders in later life. In particular, the impact of poor maternal nutrition on susceptibility to later life metabolic disease in offspring is now well documented. Several studies have now shown, at least in experimental animal models, that some components of the metabolic syndrome, induced as a consequence of developmental programming, are potentially reversible by nutritional or targeted therapeutic interventions during windows of developmental plasticity. This review will focus on critical windows of development and possible therapeutic avenues that may reduce metabolic and obesogenic risk following an adverse early life environment.

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

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

Early maternal undernutrition programs increased feed intake, altered glucose metabolism and insulin secretion, and liver function in aged female offspring

Insulin resistance and obesity are components of the metabolic syndrome that includes development of cardiovascular disease and diabetes with advancing age. The thrifty phenotype hypothesis suggests that offspring of poorly nourished mothers are predisposed to the various components of the metabolic syndrome due to adaptations made during fetal development. We assessed the effects of maternal nutrient restriction in early gestation on feeding behavior, insulin and glucose dynamics, body composition, and liver function in aged female offspring of ewes fed either a nutrient-restricted [NR 50% National Research Council (NRC) recommendations] or control (C: 100% NRC) diet from 28 to 78 days of gestation, after which both groups were fed at 100% of NRC from day 79 to lambing and through lactation. Female lambs born to NR and C dams were reared as a single group from weaning, and thereafter, they were fed 100% NRC recommendations until assigned to this study at 6 yr of age. These female offspring were evaluated by a frequently sampled intravenous glucose tolerance test, followed by dual-energy X-ray absorptiometry for body composition analysis prior to and after ad libitum feeding of a highly palatable pelleted diet for 11 wk with automated monitoring of feed intake (GrowSafe Systems). Aged female offspring born to NR ewes demonstrated greater and more rapid feed intake, greater body weight gain, and efficiency of gain, lower insulin sensitivity, higher insulin secretion, and greater hepatic lipid and glycogen content than offspring from C ewes. These data confirm an increased metabolic "thriftiness" of offspring born to NR mothers, which continues into advanced age, possibly predisposing these offspring to metabolic disease.

Elucidation of thrifty features in adult rats exposed to protein restriction during gestation and lactation

Since the introduction of the thrifty phenotype hypothesis, the potential traits of thrift have been described in increasingly broad terms but biochemical and behavioral evidence of thrift has not been well demonstrated. The objective of our studies was to use a rodent model to identify features of thrift programmed by early life protein restriction. Robust programming of thrifty features requires a thrifty nutritional environment during the entire window of developmental plasticity. Therefore, pregnant rats were exposed to a low protein diet throughout the window of developmental plasticity spanning the period of gestation and lactation and its effects on energy acquisition, storage and expenditure in the adult offspring were examined. Maternal protein restriction reduced birth weight and produced long term reductions in body and organ weights in the offspring. Low protein offspring demonstrated an increased drive to seek food as evidenced by hyperphagia that was mediated by changes in plasma leptin and ghrelin levels. Hyperphagia was accompanied by increased efficiency in converting caloric intake into body mass. The higher feed efficiency was mediated by greater insulin sensitivity. Energy expenditure of low protein offspring in locomotion was not affected either in the light or dark phase. However, low protein offspring exhibited higher resting and basal metabolic rates as evidenced by higher core body temperature in the fed and fasted states. The increased thermogenesis was not mediated by thyroid hormones but by an increased sympathetic nervous system drive as reflected by a lower areal bone mineral density and bone mineral content and lower plasma adiponectin and triglyceride levels. Elevated thermogenesis in the low protein offspring possibly offsets the effects of hyperphagia, minimizes their chances of weight gain, and improves survivability. This constellation of metabolic features in the low protein offspring will maximize survival potential in a post natal environment of nutritional scarcity and constitute a thrifty phenotype.

Maternal obesity and developmental programming of metabolic disorders in offspring: evidence from animal models

The incidence of obesity and overweight has reached epidemic proportions in the developed world as well as in those countries transitioning to first world economies, and this represents a major global health problem. Concern is rising over the rapid increases in childhood obesity and metabolic disease that will translate into later adult obesity. Although an obesogenic nutritional environment and increasingly sedentary lifestyle contribute to our risk of developing obesity, a growing body of evidence links early life nutritional adversity to the development of long-term metabolic disorders. In particular, the increasing prevalence of maternal obesity and excess maternal weight gain has been associated with a heightened risk of obesity development in offspring in addition to an increased risk of pregnancy-related complications. The mechanisms that link maternal obesity to obesity in offspring and the level of gene-environment interactions are not well understood, but the early life environment may represent a critical window for which intervention strategies could be developed to curb the current obesity epidemic. This paper will discuss the various animal models of maternal overnutrition and their importance in our understanding of the mechanisms underlying altered obesity risk in offspring.

Glucose intolerance associated with early-life exposure to maternal cafeteria feeding is dependent upon post-weaning diet

In addition to being a risk factor for adverse outcomes of pregnancy, maternal obesity may play a role in determining the long-term disease patterns observed in the resulting offspring, with metabolic and dietary factors directly programming fetal development. The present study evaluated the potential for feeding rats an obesogenic cafeteria diet (O) pre-pregnancy, during pregnancy, during lactation and for the offspring post-weaning, to programme glucose tolerance. Early-life exposure to an O diet had no significant effect on offspring food intake. Early-life programming associated with O feeding to induce maternal obesity was associated with reduced adiposity in offspring weaned onto low-fat chow. Adult offspring exposed to an O diet in early life and weaned on a chow diet had low fasting glucose and insulin concentrations and appeared to be more sensitive to insulin during an intraperitoneal glucose tolerance test. When weaned on an O diet, male offspring were more prone to glucose intolerance than females. On the basis of the area under the glucose curve, maternal O feeding at any point from pre-mating to lactation was associated with impaired glucose tolerance. The mechanism for this was not identified, although increased hepatic expression of Akt2 may have indicated disturbance of insulin signalling pathways. The observations in the present study confirm that maternal overnutrition and obesity during pregnancy are risk factors for metabolic disturbance in the resulting offspring. Although the effects on glucose homeostasis were independent of offspring adiposity, the programming of a glucose-intolerant phenotype was only observed when offspring were weaned on a diet that induced greater fat deposition.

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

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

Developmental programming of energy balance and its hypothalamic regulation

Developmental programming is an important physiological process that allows different phenotypes to originate from a single genotype. Through plasticity in early life, the developing organism can adopt a phenotype (within the limits of its genetic background) that is best suited to its expected environment. In humans, together with the relative irreversibility of the phenomenon, the low predictive value of the fetal environment for later conditions in affluent countries makes it a potential contributor to the obesity epidemic of recent decades. Here, we review the current evidence for developmental programming of energy balance. For a proper understanding of the subject, knowledge about energy balance is indispensable. Therefore, we first present an overview of the major hypothalamic routes through which energy balance is regulated and their ontogeny. With this background, we then turn to the available evidence for programming of energy balance by the early nutritional environment, in both man and rodent models. A wealth of studies suggest that energy balance can indeed be permanently affected by the early-life environment. However, the direction of the effects of programming appears to vary considerably, both between and within different animal models. Because of these inconsistencies, a comprehensive picture is still elusive. More standardization between studies seems essential to reach veritable conclusions about the role of developmental programming in adult energy balance and obesity.

The effect of gestational undernutrition on maternal weight change and fetal weight in lines of mice selected for different growth characteristics

The present study investigated whether the genetic growth characteristics (fast or slow growing, lean or fat) of a mother influences her ability to partition nutrients to developing offspring. A total of sixty-one pregnant mice of three selected lines were used: fast-growing, relatively fat (FF, n 19); fast-growing, relatively lean (FL, n 23); and normal growth, relatively lean (NL, n 19). On day 1 of pregnancy, mice were given either ad libitum access to food (control (C): n 32) or pair-fed at 80 % of C intake (restricted (R): n 29). Feed intake and dam weight were measured daily. The weight of the mouse, organs, mammary tissue and the weight of fetuses and placentas were determined at day 18 of gestation. Overall, R dams gained less than half the weight of C dams during gestation. NL dams gained the most weight, and FF dams gained the least weight (P < 0·001). R dams in the fast-growing lines mobilised significantly more body fat during gestation than the NL line (P < 0·001) and had a greater reduction in mammary tissue growth. The relative weight of the litter increased in R dams of the FF line but was reduced in both the lean lines. Undernutrition reduced fetal and placental weight, and reduced placental efficiency in all the lines. The reduction was least in the FF line and greatest in the FL line. The data suggest that selection of animals for different growth characteristics alters their response to undernutrition during pregnancy, the relatively fat line was better able to buffer its offspring from the effects of undernutrition than the lean lines, regardless of their underlying rate of growth.

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

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

Does birth weight influence physical activity in youth? A combined analysis of four studies using objectively measured physical activity

Animal models suggest growth restriction in utero leads to lower levels of motor activity. Furthermore, individuals with very low birth weight report lower levels of physical activity as adults. The aim of this study was to examine whether birth weight acts as a biological determinant of physical activity and sedentary time. This study uses combined analysis of three European cohorts and one from South America (n = 4,170). Birth weight was measured or parentally reported. Height and weight were measured and used to calculate Body Mass Index (BMI). PA was objectively measured using accelerometry for ≥3 days, ≥10 hours day. Data was standardized to allow comparisons between different monitors. Total physical activity was assessed as counts per minute (cpm), with time spent above moderate activity (MVPA) >2,000 counts and time spent sedentary (<100 counts). There was no evidence for an association between birth weight and total physical activity (p = 0.9) or MVPA (p = 0.7). Overall there was no evidence for an association between birth weight and sedentary time (p = 0.8). However in the Pelotas study we did find an association between higher birth weight (kg) and lower overall physical activity (cpm) (β = -31, 95%CI: -58, -46, p = 0.03) and higher birth weight and greater sedentary time (mins/day) (β = 16.4, 95%CI: 5.3, 27.5, p = 0.004), although this was attenuated and no longer significant with further adjustment for gestational age. Overall this combined analysis suggests that birth weight may not be an important biological determinant of habitual physical activity or sedentary behaviour in children and adolescents.

Perinatal nutrient restriction induces long-lasting alterations in the circadian expression pattern of genes regulating food intake and energy metabolism

OBJECTIVE

Several lines of evidence indicate that nutrient restriction during perinatal development sensitizes the offspring to the development of obesity, insulin resistance and cardiovascular disease in adulthood via the programming of hyperphagia and reduced energy expenditure. Given the link between the circadian clock and energy metabolism, and the resetting action of food on the circadian clock, in this study, we have investigated whether perinatal undernutrition affects the circadian expression rhythms of genes regulating food intake in the hypothalamus and energy metabolism in the liver.

DESIGN

Pregnant Sprague-Dawley rats were fed ad libitum either a control (20% protein) or a low-protein (8% protein) diet throughout pregnancy and lactation. At weaning, pups received a standard diet and at 17 and 35 days of age, their daily patterns of gene expression were analyzed by real-time quantitative PCR experiments.

RESULTS

17-day-old pups exposed to perinatal undernutrition exhibited significant alterations in the circadian expression profile of the transcripts encoding diverse genes regulating food intake, the metabolic enzymes fatty acid synthase and glucokinase as well as the clock genes BMAL1 and Period1. These effects persisted after weaning, were associated with hyperphagia and mirrored the results of the behavioral analysis of feeding. Thus, perinatally undernourished rats exhibited an increased hypothalamic expression of the orexigenic peptides agouti-related protein and neuropeptide Y. Conversely, the mRNA levels of the anorexigenic peptides pro-opiomelanocortin and cocaine and amphetamine-related transcripts were decreased.

CONCLUSION

These observations indicate that the circadian clock undergoes nutritional programming. The programming of the circadian clock may contribute to the alterations in feeding and energy metabolism associated with malnutrition in early life, which might promote the development of metabolic disorders in adulthood.

Nutrition, epigenetics, and developmental plasticity: implications for understanding human disease

There is considerable evidence for induction of differential risk of noncommunicable diseases in humans by variation in the quality of the early life environment. Studies in animal models show that induction and stability of induced changes in the phenotype of the offspring involve altered epigenetic regulation by DNA methylation and covalent modifications of histones. These findings indicate that such epigenetic changes are highly gene specific and function at the level of individual CpG dinucleotides. Interventions using supplementation with folic acid or methyl donors during pregnancy, or folic acid after weaning, alter the phenotype and epigenotype induced by maternal dietary constraint during gestation. This suggests a possible means for reducing risk of induced noncommunicable disease, although the design and conduct of such interventions may require caution. The purpose of this review is to discuss recent advances in understanding the mechanism that underlies the early life origins of disease and to place these studies in a broader life-course context.

Protein restriction in the pregnant mouse modifies fetal growth and pulmonary development: role of fetal exposure to {beta}-hydroxybutyrate

Maternal undernutrition during sensitive periods of pregnancy results in offspring predisposed towards the development of a number of diseases of adulthood, including hypertension and diabetes. In order to determine the nature of any gross alterations in fetal growth during early organogenesis, we supplied timed-mated pregnant mice with diets containing 6% protein (6%P), 9% protein (9%P) or 18% protein (18%P; control) from day 0 of pregnancy. At embryonic days 11 (E11), 12 (E12) and 13 (E13), females were killed and fetuses removed. Gross morphological analysis revealed that fetal limb growth was impaired between E11 and E12 in 6%P animals, but this recovered by E13. Likewise, fetal liver growth and lung branching morphogenesis were seen to exhibit an initial growth impairment at E12 followed by a rapid recovery by E13. Coincident with the observed changes in fetal growth, we noted an elevation in maternal hepatic triglyceride content, expression of the ketogenic 3-hydroxy-3-methylglutaryl-CoA synthase 2 (Hmgcs2) and circulating plasma β-hydroxybutyrate (BOHB). In addition, fetal liver Hmgcs2 expression was switched on by E13 in both 6%P- and 9%P-exposed animals. Exogenous BOHB did not influence branching morphogenesis in fetal lung explant cultures; however, we cannot rule out the possibility that this may occur in vivo. In conclusion, we find that disturbance of fetal growth by maternal dietary protein restriction is associated and therefore potentially indicated by changes in maternal and fetal ketone body metabolism.

Epigenetic changes in early life and future risk of obesity

The rapid increase in incidence of obesity over the past two decades cannot be explained solely by genetic and adult lifestyle factors. There is now considerable evidence that the fetal and early postnatal environments also strongly influence the risk of developing obesity in later life. Initially, human studies showed that low birth weight was associated with an increased risk of obesity but increasingly there is evidence that overnutrition in the early life can also increase susceptibility to future obesity. These findings have now been replicated in animal models, which have shown that both maternal under- and overnutrition can induce persistent changes in gene expression and metabolism. The mechanism by which the maternal nutritional environment induces such changes is beginning to be understood and involves the altered epigenetic regulation of specific genes. In this review, we discuss the recent evidence that shows that early-life environment can induce altered epigenetic regulation leading to the induction of an altered phenotype. The demonstration of a role for altered epigenetic regulation of genes in the developmental induction of obesity opens the possibility that interventions, either through nutrition or specific drugs, may modify long-term obesity risk and combat this rapid rise in obesity.

Effect of late gestation low protein supply to mink (Mustela vison) dams on reproductive performance and metabolism of dam and offspring

Protein malnutrition in utero that induces permanent changes in metabolism has been investigated intensively in various animals in recent years, but to the best of our knowledge, not yet in the mink, a strict carnivore. In the present study, minks were fed either a low-protein (LP) diet, i.e., with a protein:fat:carbohydrate ratio of 14:51:35% of metabolisable energy (ME), or an adequate-protein diet (AP), i.e. 29:56:15% of ME, from when implantation was completed until parturition (17.9 +/- 3.6 days). Respiration and balance experiments were performed during both gestation and lactation. Plasma concentrations of leptin, IGF-1, and insulin were determined by radioimmunoassay; the relative abundances of glucose-6-phosphatase (G-6-Pase), fructose-1,6-bisphosphatase (Fru-1,6-P2ase), phosphoenol-pyruvate carboxykinase (PEPCK), and pyruvate kinase (PKM2) were determined in liver, and abundances of adiponectin and leptin in adipose tissue were determined by real-time quantitative PCR (q PCR). The protein supply only affected quantitative metabolism traits during the period of differentiated feeding. The dietary composition was reflected in the nitrogen metabolism and substrate oxidation, but no effects remained during lactation. The LP dams tended to have a smaller liver mass in relation to body weight than did AP dams (2.5% vs. 2.9%; p = 0.09), significantly less leptin mRNA (p < 0.05), and 30.6% fewer kits per mated female (p = 0.03). Furthermore, F1-generation kits exposed to protein restriction during foetal life (FLP1; 10.3 g) had a lower birth weight (p = 0.004) than did F1-generation kits exposed to adequate protein (FAP1; 11.3 g). Differences remained significant until 21 days of age (120.4 g vs. 127.6 g; p = 0.005). The FLP1 foetuses displayed a lower abundance of Fru-1,6-P2ase mRNA (p = 0.007) and of PKM2 mRNA (p = 0.002) than did FAP1 foetuses. Whether these changes during foetal life cause permanent changes in the glucose homeostasis of the offspring and result in the transmission of epigenetic phenotypic changes, as seen in the rat, needs further investigation.

Moderate caloric restriction during gestation results in lower arcuate nucleus NPY- and alphaMSH-neurons and impairs hypothalamic response to fed/fasting conditions in weaned rats

AIM

We aimed to characterize the developmental programming effects of moderate caloric restriction during early pregnancy on factors involved in hypothalamic control of energy balance.

METHODS

Twenty-five-days-old offspring Wistar rats from 20% caloric restricted dams (from 1 to 12 days of pregnancy) (CR) and from control dams were studied under fed and 12 h fasting conditions. Morphometric studies on arcuate nucleus (ARC) and determinations of circulating parameters and hypothalamic levels of neuropeptide Y (NPY), proopiomelanocortin (POMC), long-form leptin receptor (ObRb), insulin receptor (InsR) and suppressor of cytokine signalling-3 (SOCS-3) mRNA were performed.

RESULTS

CR animals did not show different body weight with respect to their controls, but presented higher food intake. They exhibited lower neuropeptide Y- and alpha-melanocyte-stimulating hormone-neurons (decreases of 18 and 13% in males, and 10 and 18% in females respectively) and lower total cells (decrease of 3% in males and 18% in females) in ARC. Under fed conditions, CR animals presented lower circulating leptin and ghrelin levels (decreases of 37 and 43% in males, and 15 and 34% in females respectively); furthermore, hypothalamic POMC, NPY (only in females), ObRb and InsR mRNA levels were reduced (39, 16 and 26% in males, and 112, 33, 61 and 56% in females), and those of SOCS-3 were increased (86% in males and 74% in females). Unlike control animals, under fasting conditions, ObRb, InsR and POMC mRNA levels did not decrease in CR females, and NPY mRNA decreased instead of increase in CR males.

CONCLUSIONS

Moderate caloric restriction during gestation affects offspring hypothalamic structure and function, impairing its response to fed/fasting conditions, which suggests a predisposition to insulin and leptin resistance.

Maternal high fat feeding and gestational dietary restriction: effects on offspring body weight, food intake and hypothalamic gene expression over three generations in mice

Excessive gestational weight gain and maternal obesity have both been associated with increased incidence of obesity and metabolic disorder in offspring in both humans and animal models. The objectives of this study were to determine (1) whether mild gestational food restriction during the third trimester (GFR) would alter food intake and growth parameters of offspring, (2) whether effects of GFR depended on diet (high fat [HF] vs chow), (3) whether effects of excessive gestational weight gain (WG) would become magnified across generations, and (4) whether diet and GFR would alter hypothalamic gene expression in adult offspring. Three generations of female C57BL/6 mice were fed chow or HF diet, mated at 11 weeks of age and assigned to ad libitum feeding or 25% GFR. Offspring were fed the same diet as their mothers. Results showed (1) maternal gestational WG was positively correlated with offspring WG. (2) HF offspring weighed less (p<0.01) at weaning (WWT) but gained more during the 8 weeks after weaning than chow-fed offspring (p<0.05), resulting in higher final body weights (BW) (p<0.01). (3) HF males from GFR mothers had higher WWT (p<0.05), but subsequent WG and final BW were less (p<0.05) compared to males from ad lib mothers. (4) In the HF group, GFR also resulted in decreased FI (p<0.05) and FE (p<0.07) in offspring, compared to offspring from ad lib mothers. (5) In generation 3, hypothalamic expression of tyrosine hydroxylase was lower in HF males from GFR mothers compared to HF males from ad lib mothers (p<0.05). In conclusion, gender and maternal GFR had independent effects on growth and FI, and hypothalamic gene expression was dependent on both gender and maternal GFR in HF offspring. Even mild food restriction of obese mothers during pregnancy may have beneficial effects in reducing the risk or degree of obesity in offspring.

Maternal protein restriction with or without folic acid supplementation during pregnancy alters the hepatic transcriptome in adult male rats

Feeding pregnant rats a protein-restricted (PR) diet induces altered expression of candidate genes in the liver of the adult offspring, which can be prevented by supplementation of the PR diet with folic acid (PRF). We investigated the effect of maternal nutrition during pregnancy on the liver transcriptome in their adult male offspring. Pregnant rats were fed control, PR or PRF diets. Male offspring were killed on day 84. The liver transcriptome was analysed by microarray (six livers per maternal dietary group) followed by post hoc analysis of relative mRNA levels and gene ontology. These results were confirmed for selected genes by real-time RT-PCR. There were 311 genes that differed significantly ( >or= 1.5-fold change; P < 0.05) between PR offspring (222 increased) and control offspring, while 191 genes differed significantly between PRF offspring (forty-five increased) compared with offspring of control dams. There were sixteen genes that were significantly altered in both PR and PRF offspring compared with controls. Ion transport, developmental process, and response to reactive oxygen species (RROS) and steroid hormone response (SHR) ontologies were altered in PR offspring. Folic acid supplementation prevented changes within RROS and SHR response pathways, but not in ion transport or developmental process. There was no effect of maternal PR on mRNA expression of imprinted genes. Insulin 1 and Pleckstrin homology-like domain family A member 2 were increased significantly in PRF compared with PR offspring. The present findings show that the pattern of induced changes in the adult liver transcriptome were dependent on maternal protein and folic acid intakes during pregnancy.