The timing of nutrient restriction during rat pregnancy/lactation alters metabolic syndrome phenotype

Nutrigenetic and Epigenetic Mechanisms of Maternal Nutrition-Induced Glucolipid Metabolism Changes in the Offspring

Maternal nutrition during pregnancy regulates the offspring's metabolic homeostasis, including insulin sensitivity and the metabolism of glucose and lipids. The fetus undergoes a crucial period of plasticity in the uterus; metabolic changes in the fetus during pregnancy caused by maternal nutrition not only influence fetal growth and development but also have a long-term or even life-long impact for the offspring. Epigenetic modifications, such as DNA methylation, histone modification, and non-coding RNAs, play important roles in intergenerational and transgenerational effects. In this context, this narrative review comprehensively summarizes and analyzes the molecular mechanisms underlying how maternal nutrition, including a high-fat diet, polyunsaturated fatty acid diet, methyl donor nutrient supplementation, feed restriction, and protein restriction during pregnancy, impacts the genes involved in glucolipid metabolism in the liver, adipose tissue, hypothalamus, muscle, and oocytes of the offspring in terms of the epigenetic modifications. This will provide a foundation for the further exploration of nutrigenetic and epigenetic mechanisms for integrative mother-child nutrition and promotion of the offspring's health through the regulation of maternal nutrition during pregnancy. Note: This paper is part of the Nutrition Reviews Special Collection on Precision Nutrition.

Genomic imprinting and environmental epigenetics: Their influence on sheep reproductive traits across parities

This study aimed to explore the impact of genomic imprinting on the genetic variance of composite reproductive traits across three parities in Baluchi sheep. The traits analyzed included litter mean weight per lamb born (LMWLB), litter mean weight per lamb weaned (LMWLW), total litter weight at birth (TLWB), and total litter weight at weaning (TLWW). We employed a univariate linear animal model for each trait, treating performance across parities as separate traits. Twenty-four animal models were assessed, incorporating direct additive genetic effects, maternal genetic effects, maternal permanent environmental effects, direct and maternal genetic covariances, as well as maternal and paternal imprinting. Model selection was based on Akaike's Information Criterion (AIC). Direct heritability estimates for the traits were generally low, ranging from 0.039 ± 0.017 for LMWLW to 0.085 ± 0.028 for TLWW. TLWB and TLWW exhibited higher heritability than LMWLB and LMWLW in their respective parities. In the best model (model 24), maternal imprinting heritability estimates from the first to third parity were 0.059 ± 0.016, 0.060 ± 0.013, and 0.085 ± 0.021 for TLWB, 0.075 ± 0.021, 0.068 ± 0.025, and 0.048 ± 0.016 for LMWLB, 0.051 ± 0.013, 0.065 ± 0.019, and 0.068 ± 0.020 for TLWW, and, 0.072 ± 0.012, 0.057 ± 0.018 and 0.054 ± 0.011 for LMWLW, respectively. Paternal imprinting heritability estimates were consistently lower than maternal imprinting estimates, with values across parities ranging from 0.001 ± 0.024 to 0.019 ± 0.032 for TLWB, 0.005 ± 0.022-0.010 ± 0.019 for LMWLB, 0.012 ± 0.05-0.017 ± 0.05 for TLWW and, 0.013 ± 0.01-0.016 ± 0.01 for LMWLW. In conclusion, imprinting effects should be included in breeding programs to increase the accuracy of genetic evaluation.

Neurodevelopmental Programming of Adiposity: Contributions to Obesity Risk

This review analyzes the published evidence regarding maternal factors that influence the developmental programming of long-term adiposity in humans and animals via the central nervous system (CNS). We describe the physiological outcomes of perinatal underfeeding and overfeeding and explore potential mechanisms that may mediate the impact of such exposures on the development of feeding circuits within the CNS-including the influences of metabolic hormones and epigenetic changes. The perinatal environment, reflective of maternal nutritional status, contributes to the programming of offspring adiposity. The in utero and early postnatal periods represent critically sensitive developmental windows during which the hormonal and metabolic milieu affects the maturation of the hypothalamus. Maternal hyperglycemia is associated with increased transfer of glucose to the fetus driving fetal hyperinsulinemia. Elevated fetal insulin causes increased adiposity and consequently higher fetal circulating leptin concentration. Mechanistic studies in animal models indicate important roles of leptin and insulin in central and peripheral programming of adiposity, and suggest that optimal concentrations of these hormones are critical during early life. Additionally, the environmental milieu during development may be conveyed to progeny through epigenetic marks and these can potentially be vertically transmitted to subsequent generations. Thus, nutritional and metabolic/endocrine signals during perinatal development can have lifelong (and possibly multigenerational) impacts on offspring body weight regulation.

Accumbal μ-opioid receptors and salt taste-elicited hedonic responses in a rodent model of prenatal adversity, and their correlates using human functional genomics

Prenatal adversity is associated with behavioral obesogenic features such as preference for palatable foods. Salt appetite may play a role in the development of adiposity and its consequences in individuals exposed to prenatal adversity, and sodium consumption involves individual differences in accumbal µ-opioid receptors function. We investigated the hedonic responses to salt and the levels of µ-opioid receptors and tyrosine hydroxylase in the nucleus accumbens (Nacc) of pups from an animal model of prenatal dietary restriction. In children, we evaluated the interaction between fetal growth and the genetic background associated with the accumbal µ-opioid receptor gene (OPRM1) expression on sodium consumption during a snack test. Sprague-Dawley dams were randomly allocated from pregnancy day 10 to receive an ad libitum (Adlib) or a 50% restricted (FR) diet. The pups' hedonic responses to a salt solution (NaCl 2%) or water were evaluated on the first day of life. FR and Adlib pups differ in their hedonic responses to salt, and there were decreased levels of accumbal µ-opioid and p-µ-opioid receptors in FR pups. In humans, a test meal and genotyping from buccal epithelial cells were performed in 270 children (38 intrauterine growth restricted-IUGR) at 4 years old from a Canadian prospective cohort (MAVAN). The OPRM1 genetic score predicted the sodium intake in IUGR children, but not in controls. The identification of mechanisms involved in the brain response to prenatal adversity and its consequences in behavioral phenotypes and risk for chronic diseases later in life is important for preventive and therapeutic purposes.

Zinc-nanoparticles alleviate the ovarian damage induced by bacterial lipopolysaccharide (LPS) in pregnant rats and their fetuses

Lipopolysaccharide (LPS) is an endotoxin derived from the cell wall of Gram-negative bacteria. LPS exposure during early gestation is associated with adverse effects on the placenta as well as on developmental outcomes, including embryonic resorption, fetal death, congenital teratogenesis, and fetal growth retardation. This work aimed to explore the adverse effects of LPS injected at an early stage of gestation on the gonads of pregnant rats and the ovaries of their pups and the role of zinc nanoparticles (Zn-NPs) against these adverse effects. Twenty-four pregnant rats were used in this study. They were divided at gestation day 4 into four groups (n = 6): control, Zn-NPs (20 mg/kg orally from gestation day E14 till the end of weaning), LPS (50 µg/kg at gestation days E7 and E9), and LPS + Zn-NPs group. The body weight and placenta weight were recorded at gestational day 16. At postnatal day 21 (weaning), the mothers rats and their offspring were sacrificed and immediately dissected to remove the ovaries and uteri from the mothers and the ovaries from their offspring for subsequent biochemical, histological, and immunohistochemical investigations. The obtained results revealed that LPS exposure during early gestation caused severe histopathological alterations in the placenta, uterus, and ovaries of mothers, as well as in the ovaries of their pups. Also, the uterine and ovarian sections displayed a positive reaction for caspase-3 antibody and a negative reaction for Bcl-2 antibody, which reflects the apoptotic effect of LPS. Additionally, remarkable reductions in the levels of antioxidants (superoxide dismutase and catalase) and significant increases in malondialdehyde (MDA) levels were recorded in the serum of LPS-treated mothers and in the ovarian tissues of their offspring. Further biochemical analysis of the ovarian tissues from LPS-maternally treated offspring showed a significant increase in the levels of caspase-3, TNF-α, and TGF-β1, but a significant decrease in the level of IGF-1. On the other hand, treatment of mothers with Zn-NPs from day 14 of gestation until the weaning day (21st day postnatal) successfully ameliorated most of the deleterious histopathological, immunohistochemical, and biochemical changes induced by LPS.

Relationship between insulin and Netrin-1/DCC guidance cue pathway regulation in the prefrontal cortex of rodents exposed to prenatal dietary restriction

Fetal restriction (FR) alters insulin sensitivity, but it is unknown how the metabolic profile associated with restriction affects development of the dopamine (DA) system and DA-related behaviors. The Netrin-1/DCC guidance cue system participates in maturation of the mesocorticolimbic DA circuitry. Therefore, our objective was to identify if FR modifies Netrin-1/DCC receptor protein expression in the prefrontal cortex (PFC) at birth and mRNA in adulthood in rodent males. We used cultured HEK293 cells to assess if levels of miR-218, microRNA regulator of DCC, are sensitive to insulin. To assess this, pregnant dams were subjected to a 50% FR diet from gestational day 10 until birth. Medial PFC (mPFC) DCC/Netrin-1 protein expression was measured at P0 at baseline and Dcc/Netrin-1 mRNA levels were quantified in adults 15 min after a saline/insulin injection. miR-218 levels in HEK-293 cells were measured in response to insulin exposure. At P0, Netrin-1 levels are downregulated in FR animals in comparison to controls. In adult rodents, insulin administration results in an increase in Dcc mRNA levels in control but not FR rats. In HEK293 cells, there is a positive correlation between insulin concentration and miR-218 levels. Since miR-218 is a Dcc gene expression regulator and our in vitro results show that insulin regulates miR-218 levels, we suggest that FR-induced changes in insulin sensitivity could be affecting Dcc expression via miR-218, impacting DA system maturation and organization. As fetal adversity is linked to nonadaptive behaviors later in life, this may contribute to early identification of vulnerability to chronic diseases associated with fetal adversity.

Thermoneutrality effects on developmental programming of obesity

Developmental programming studies using mouse models have housed the animals at human thermoneutral temperatures (22°C) which imposes constant cold stress. As this impacts energy homeostasis, we investigated the effects of two housing temperatures (22°C and 30°C) on obesity development in male and female offspring of Control and FR dams. Pregnant mice were housed at 22°C (cold-exposed, CE) or 30°C (thermoneutrality, TN) room temperature. At gestational age e10, mice were fed either an ad libitum diet (Control) or were 30% food-restricted (FR) to produce low birth weight newborns. Following delivery, all dams were fed an ad libitum diet and maternal mice continued to nurse their own pups. At 3 weeks of age, offspring were weaned to an ad libitum diet and housed at similar temperatures as their mothers. Body weights and food intake were monitored. At 6 months of age, body composition and glucose tolerance test were determined, after which, brain and adipose tissue were collected for analysis. FR/CE and FR/TN offspring exhibited hyperphagia and were significantly heavier with increased adiposity as compared to their respective Controls. There was sex-specific effects of temperature in both groups. Male offspring at TN were heavier with increased body fat, though the food intake was decreased as compared to CE males. This was reflected by hypertrophic adipocytes and increased arcuate nucleus satiety/appetite ratio. In contrast, female offspring were not impacted by housing temperature. Thus, unlike female offspring, there was a significant interaction of diet and temperature evident in the male offspring with accentuated adverse effects evident in FR/TN males.

Novel intrauterine growth retardation model: effects of maternal subtotal nephrectomy on neonates

Changes in body weight (BW), systolic blood pressure (SBP), and localization of renin in the kidneys of neonates born to normal mothers (C neonates) or to five-sixths (5/6) nephrectomized (2/3 left kidney and right kidney) mothers (Nx neonates) were studied. Maternal 5/6 nephrectomy caused weight loss in neonates but no differences in SBP or renin localization. Culling Nx neonates to a litter of 3 at 1 day after birth resulted in growth catching up with C neonates from 3 weeks old and increases in both SBP and renin-positive cells in neonatal kidney. These findings revealed that maternal 5/6 nephrectomy results in low-birth-weight neonates and that these neonates are at increased risk of metabolic syndrome by catch-up growth.

Hypothalamic Nesfatin-1 Resistance May Underlie the Development of Type 2 Diabetes Mellitus in Maternally Undernourished Non-obese Rats

Intrauterine growth retardation (IUGR) poses a high risk for developing late-onset, non-obese type 2 diabetes (T2DM). The exact mechanism underlying this phenomenon is unknown, although the contribution of the central nervous system is recognized. The main hypothalamic nuclei involved in the homeostatic regulation express nesfatin-1, an anorexigenic neuropeptide and identified regulator of blood glucose level. Using intrauterine protein restricted rat model (PR) of IUGR, we investigated, whether IUGR alters the function of nesfatin-1. We show that PR rats develop fat preference and impaired glucose homeostasis by adulthood, while the body composition and caloric intake of normal nourished (NN) and PR rats are similar. Plasma nesfatin-1 levels are unaffected by IUGR in both neonates and adults, but pro-nesfatin-1 mRNA expression is upregulated in the hypothalamus of adult PR animals. We find that centrally injected nesfatin-1 inhibits the fasting induced neuronal activation in the hypothalamic arcuate nucleus in adult NN rats. This effect of nesfatin-1 is not seen in PR rats. The anorexigenic effect of centrally injected nesfatin-1 is also reduced in adult PR rats. Moreover, chronic central nesfatin-1 administration improves the glucose tolerance and insulin sensitivity in NN rats but not in PR animals. Birth dating of nesfatin-1 cells by bromodeoxyuridine (BrDU) reveals that formation of nesfatin-1 cells in the hypothalamus of PR rats is disturbed. Our results suggest that adult PR rats acquire hypothalamic nesfatin-1-resistance, probably due to the altered development of the hypothalamic nesfatin-1 cells. Hypothalamic nesfatin-1-resistance, in turn, may contribute to the development of non-obese type T2DM.

Effects of Glucagon-like peptide 1 (GLP-1) analogs in the hippocampus

The glucagon-like peptide-1 (GLP-1) is a pleiotropic hormone very well known for its incretin effect in the glucose-dependent stimulation of insulin secretion. However, GLP-1 is also produced in the brain, and it displays critical roles in neuroprotection by activating the GLP-1 receptor signaling pathways. GLP-1 enhances learning and memory in the hippocampus, promotes neurogenesis, decreases inflammation and apoptosis, modulates reward behavior, and reduces food intake. Its pharmacokinetics have been improved to enhance the peptide's half-life, enhancing exposure and time of action. The GLP-1 agonists are successfully in clinical use for the treatment of type-2 diabetes, obesity, and clinical evaluation for the treatment of neurodegenerative diseases.

Early adversity and insulin: neuroendocrine programming beyond glucocorticoids

Exposure to direct or contextual adversities during early life programs the functioning of the brain and other biological systems, contributing to the development of physical as well as mental health issues in the long term. While the role of glucocorticoids in mediating the outcomes of early adversity has been explored for many years, less attention has been given to insulin. Beyond its metabolic effects in the periphery, central insulin action affects synaptic plasticity, brain neurotransmission, and executive functions. Knowledge about the interactions between the peripheral metabolism and brain function from a developmental perspective can contribute to prevention and diagnosis programs, as well as early interventions for vulnerable populations.

Links Between Maternal Cardiovascular Disease and the Health of Offspring

Maternal cardiovascular disease (CVD) during pregnancy is on the rise worldwide, as both more women with congenital heart disease are reaching childbearing age, and conditions such as diabetes, hypertension, and obesity are becoming more prevalent. However, the extent to which maternal CVD influences offspring health, as a neonate and later in childhood and adolescence, remains to be fully understood. The thrifty phenotype hypothesis, by which a fetus adapts to maternal and placental changes to survive a nutrient-starved environment, may provide an answer to the mechanism of maternal CVD and its impact on the offspring. In this narrative review, we aim to provide a review of the literature pertaining to the impact of maternal cardiovascular and hypertensive disease on the health of neonates, children, and adolescents. This review demonstrates that maternal CVD leads to higher rates of complications among neonates. Ultimately, our review supports the hypothesis that maternal CVD leads to intrauterine growth restriction (IUGR), which, through the thrifty phenotype hypothesis and vascular remodelling, can have health repercussions, including an impact on CVD risk, both in the immediate newborn period as well as later throughout the life of the offspring. Further research remains crucial in elucidating the mechanism of maternal CVD long-term effects on offspring, as further understanding could lead to preventive measures to optimise offspring health, including modifiable lifestyle changes. Potential treatments for this at-risk offspring group could mitigate risk, but further studies to provide evidence are needed.

Leptin Chronic Effect on Differentiation, Ion Currents and Protein Expression in N1E-115 Neuroblastoma Cells

<b>Background and Objective:</b> Arcuate nucleus (ARC), a component of appetite-regulatory factors, contains populations of both orexigenic and anorexigenic neurons and one of the fundamental components of its system is leptin. Studies have evidenced the critical neurotrophic role in the development of ARC. To determine such effects on neuron development, N1E-115 neuroblastoma cells were used as an ARC model. <b>Materials and Methods:</b> N1E-115 neuroblastoma cells were treated with leptin [10 nM] for 24, 48 and 72 hrs. Dimethyl sulfoxide (DMSO) 1.5% was used as a known drug that promotes neurite expression. Cells percentage (%) that developed neurites was evaluated by bright field microscopy. Patch-clamp electrophysiology was used to analyze membrane ion currents, RT-PCR for quantifying changes in mRNA expression of anorexic peptides, proopiomelanocortin (POMC) and cocaine and amphetamine-related transcript (CART), in addition to principal Na<sub>v</sub>, Ca<sub>v</sub> ion channel subunits. <b>Results:</b> N1E-115 cells treated with leptin show neurite expression after 24 hrs of treatment, similar effects were obtained with DMSO. Leptin (time-dependent) increases the inward current in comparison with the control value at 72 hrs. Outward currents were not affected by leptin. Leptin and DMSO increased Na<sup>+</sup> and Ca<sup>2+</sup> current without changes in the kinetic properties. Lastly, leptin promotes an increase in mRNA level expression of transcripts to POMC, CART, Na<sub>v</sub>1.2 and Ca<sub>v</sub>1.3. <b>Conclusion:</b> Leptin chronic treatment promotes neurite expression, Up-regulation of Na<sup>+</sup> and Ca<sup>2+</sup> ion channels determining neuronal excitability, besides increasing the mRNA level expression of anorexic peptides POMC and CART in neuroblastoma N1E-115.

Environmental mismatch and obesity in humans: The Jerusalem Perinatal Family Follow-Up Study

BACKGROUND

According to the hypothesis of Gluckman and Hanson, mismatch between the developmental and postdevelopmental environments may lead to detrimental health impacts such as obesity. While several animal studies support the mismatch theory, there is a scarcity of evidence from human-based studies.

OBJECTIVES

Our study aims to examine whether a mismatch between the developmental and young-adult environments affect obesity in young adults of the Jerusalem Perinatal Family Follow-Up Study.

METHODS

Data from The Jerusalem Perinatal Family Follow-Up Study birth cohort was used to characterize early and late environments using offspring and parental sociodemographic and lifestyle information at birth, age 32 (n = 1140) and 42 (n = 404). Scores characterizing the early and late environments were constructed using factor analysis. To assess associations of mismatch with obesity, regression models were fitted using the first factor of each environment and adiposity measures at age 32 and 42.

RESULTS

Having a stable non-beneficial environment at birth and young-adulthood was most strongly associated with increased adiposity, while a stable beneficial environment was most favorable. The transition from a beneficial environment at birth to a less beneficial environment at young-adulthood was associated with higher obesity measures, including higher BMI (β = 0.979; 95% CI: 0.029, 1.929), waist circumference (β = 2.729; 95% CI: 0.317, 5.140) and waist-hip ratio (β = 0.017; 95% CI: 0.004, 0.029) compared with those experiencing a beneficial environment at both time points. Transition from a less beneficial environment at birth to a beneficial environment at adulthood was also associated with higher obesity measurements (BMI -β = 1.116; 95% CI: 0.085, 2.148; waist circumference -β = 2.736; 95% CI: 0.215, 5.256).

CONCLUSIONS

This study provides some support for the mismatch hypothesis. While there is indication that an accumulation of the effects of the non-beneficial environment has the strongest detrimental impact on obesity outcomes, our results also indicate that a mismatch between the developmental and later environments may result in maladaptation of the individual leading to obesity.

Maternal food restriction-induced intrauterine growth restriction in a rat model leads to sex-specific adipogenic programming

Intrauterine growth restriction (IUGR) leads to offspring obesity. In a maternal food restriction (MFR) during pregnancy-related IUGR rat model, bone marrow stem cells showed enhanced adipogenic programming; however, the effect of IUGR on white adipose tissue (WAT) progenitors is unknown. Here, by mRNA and functional profiling, we determined sex-specific adipogenic programming of WAT progenitors isolated from pups on the postnatal day (PND) 1 and 21. On PND1, PPARγ and Pref-1 expression was significantly downregulated in preadipocytes of both MFR males and females; however, at PND21, preadipocytes of MFR males showed upregulation in these genes. Even following adipogenic induction, both male and female MFR adipocytes exhibited lower PPARγ, ADRP, and adiponectin levels at PND1; however, at PND21 MFR male adipocytes showed an upward trend in the expression of these genes. An adipogenesis-specific RT-PCR array showed that male MFR adipocytes were programmed to exhibit stronger adipogenic propensity than females. Last, serum sex hormone and adipocyte estrogen/testosterone receptor expression profiles provide preliminary insights into the possible mechanism underlying sex-specific adipogenic programming in the IUGR offspring. In summary, IUGR programs WAT preadipocytes to greater adipogenic potential in males. Although the altered adipogenic programming following MFR was detectable at PND1, the changes were more pronounced at PND21, suggesting a potential role of postnatal nutrition in facilitating the sex-specific adipogenic programming in the IUGR offspring.

Maternal Malnutrition Affects Hepatic Metabolism through Decreased Hepatic Taurine Levels and Changes in HNF4A Methylation

Fetal programming implies that the maternal diet during pregnancy affects the long-term health of offspring. Although maternal diet influences metabolic disorders and non-alcoholic fatty liver disease in offspring, the hepatic mechanisms related to metabolites are still unknown. Here, we investigated the maternal diet-related alterations in metabolites and the biological pathway in male offspring at three months of age. Pregnant rats were exposed to 50% food restriction during the prenatal period or a 45% high-fat diet during the prenatal and postnatal periods. The male offspring exposed to food restriction and high-fat diets had lower birth weights than controls, but had a catch-up growth spurt at three months of age. Hepatic taurine levels decreased in both groups compared to controls. The decreased hepatic taurine levels in offspring affected excessive lipid accumulation through changes in hepatocyte nuclear factor 4 A methylation. Moreover, the alteration of gluconeogenesis in offspring exposed to food restriction was observed to a similar extent as that of offspring exposed to a high fat diet. These results indicate that maternal diet affects the dysregulation in hepatic metabolism through changes in taurine levels and HNF4A methylation, and predisposes the offspring to Type 2 diabetes and non-alcoholic fatty liver disease in later life.

Long-term effects of pro-opiomelanocortin methylation induced in food-restricted dams on metabolic phenotypes in male rat offspring

Objective

Maternal malnutrition affects the growth and metabolic health of the offspring. Little is known about the long-term effect on metabolic indices of epigenetic changes in the brain caused by maternal diet. Thus, we explored the effect of maternal food restriction during pregnancy on metabolic profiles of the offspring, by evaluating the DNA methylation of hypothalamic appetite regulators at 3 weeks of age.

Methods

Sprague-Dawley rats were divided into 2 groups: a control group and a group with a 50% food-restricted (FR) diet during pregnancy. Methylation and expression of appetite regulator genes were measured in 3-week-old offspring using pyrosequencing, real-time polymerase chain reaction, and western blotting analyses. We analyzed the relationship between DNA methylation and metabolic profiles by Pearson's correlation analysis.

Results

The expression of pro-opiomelanocortin (POMC) decreased, whereas DNA methylation significantly increased in male offspring of the FR dams, compared to the male offspring of control dams. Hypermethylation of POMC was positively correlated with the levels of high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol in 3-week-old male offspring. In addition, there were significant positive correlations between hypermethylation of POMC and the levels of triglycerides, HDL-C, and leptin in 6-month-old male offspring.

Conclusion

Our findings suggest that maternal food restriction during pregnancy influences the expression of hypothalamic appetite regulators via epigenetic changes, leading to the development of metabolic disorders in the offspring.

Nutrition and its role in epigenetic inheritance of obesity and diabetes across generations

Nutritional constraints including not only caloric restriction or protein deficiency, but also energy-dense diets affect metabolic health and frequently lead to obesity and insulin resistance, as well as glucose intolerance and type 2 diabetes. The effects of these environmental factors are often mediated via epigenetic modifiers that target the expression of metabolic genes. More recently, it was discovered that such parentally acquired metabolic changes can alter the metabolic health of the filial and grand-filial generations. In mammals, this epigenetic inheritance can either follow an intergenerational or transgenerational mode of inheritance. In the case of intergenerational inheritance, epimutations established in gametes persist through the first round of epigenetic reprogramming occurring during preimplantation development. For transgenerational inheritance, epimutations persist additionally throughout the reprogramming that occurs during germ cell development later in embryogenesis. Differentially expressed transcripts, genomic cytosine methylations, and several chemical modifications of histones are prime candidates for tangible marks which may serve as epimutations in inter- and transgenerational inheritance and which are currently being investigated experimentally. We review, here, the current literature in support of epigenetic inheritance of metabolic traits caused by nutritional constraints and potential mechanisms in man and in rodent model systems.

Role of miR-29 in mediating offspring lung phenotype in a rodent model of intrauterine growth restriction

Considerable epidemiological and experimental evidence supports the concept that the adult chronic lung disease (CLD), is due, at least in part, to aberrations in early lung development in response to an abnormal intrauterine environment; however, the underlying molecular mechanisms remain unknown. We used a well-established rat model of maternal undernutrition (MUN) during pregnancy that results in offspring intrauterine growth restriction (IUGR) and adult CLD to test the hypothesis that in response to MUN, excess maternal glucocorticoids (GCs) program offspring lung development to a CLD phenotype by altering microRNA (miR)-29 expression, which is a key miR in regulating extracellular matrix (ECM) deposition during development and injury-repair. At postnatal day 21 and 5 mo, compared with the control offspring lung, MUN offspring lung miR-29 expression was significantly decreased in conjunction with an elevated expression of multiple downstream target ECM proteins [collagen (COL)1A1, COL3A1, COL4A5, and elastin], at both mRNA and protein levels. Importantly, MUN-induced changes in miR-29 and target gene expressions were at least partially blocked in the lungs of offspring of MUN dams treated with metyrapone, a selective GC synthesis inhibitor. Furthermore, dexamethasone treatment of cultured fetal rat lung fibroblasts significantly induced miR-29 expression along with the suppression of target ECM proteins. These data, along with the previously known role of miR-29 in regulating ECM deposition in vascular tissue in the MUN offspring, suggest miR-29 to be a common mechanistic denominator for the vascular and pulmonary phenotypes in the IUGR offspring, providing a novel potential therapeutic target.

The effects of sildenafil citrate on feto-placental development and haemodynamics in a rabbit model of intrauterine growth restriction

The present study evaluated the effectiveness of sildenafil citrate (SC) to improve placental and fetal growth in a diet-induced rabbit model of intrauterine growth restriction (IUGR). Pregnant rabbits were fed either ad libitum (Group C) or restricted to 50% of dietary requirements (Group R) or restricted and treated with SC (Group SC). The treatment with SC improved placental development by increasing vascularity and vessel hypertrophy in the decidua. The assessment of feto-placental haemodynamics showed higher resistance and pulsatility indices at the middle cerebral artery (MCA) in fetuses treated with SC when compared with Group R, which had increased systolic peak and time-averaged mean velocities at the MCA. Furthermore, fetuses in the SC group had significantly higher biparietal and thoracic diameters and longer crown-rump lengths than fetuses in Group R. Hence, the SC group had a reduced IUGR rate and a higher kit size at birth compared with Group R. In conclusion, SC may provide potential benefits in pregnancies with placental insufficiency and IUGR, partially counteracting the negative effects of food restriction on placental development and fetal growth. However, the present study also found evidence of a possible blood overflow in the brain that warrants further investigation.

Sex-dimorphic acceleration of pericardial, subcutaneous, and plasma lipid increase in offspring of poorly nourished baboons

Developmental programming by reduced maternal nutrition alters function in multiple offspring physiological systems, including lipid metabolism. We have shown that intrauterine growth restriction (IUGR) leads to offspring cardiovascular dysfunction with an accelerated aging phenotype in our nonhuman primate, baboon model. We hypothesized age-advanced pericardial fat and blood lipid changes. In pregnancy and lactation, pregnant baboons ate ad lib (control) or 70% ad lib diet (IUGR). We studied baboon offspring pericardial lipid deposition with magnetic resonance imaging at 5-6 years (human equivalent 20-24 years), skinfold thickness, and serum lipid profile at 8-9 years (human equivalent 32-36 years), comparing values with a normative life-course baboon cohort, 4-23 years. Increased pericardial fat deposition occurred in IUGR males but not females. Female but not male total cholesterol, low-density lipoprotein, and subcutaneous fat were increased with a trend of triglycerides increase. When comparing IUGR changes to values in normal older baboons, the increase in male apical pericardial fat was equivalent to advancing age by 6 years and the increase in female low-density lipoprotein to an increase of 3 years. We conclude that reduced maternal diet accelerates offspring lipid changes in a sex-dimorphic manner. The interaction between programming and accelerated lipogenesis warrants further investigation.

Gestational hypoxia disrupts the neonatal leptin surge and programs hyperphagia and obesity in male offspring in the Sprague-Dawley rat

The effect of gestational hypoxia on the neonatal leptin surge, development of hypothalamic arcuate nuclei (ARH) projections and appetite that could contribute to the programming of offspring obesity is lacking. We examined the effect of 12% O₂ from gestational days 15–19 in the Sprague-Dawley rat on post-weaning appetite, fat deposition by MRI, adipose tissue cytokine expression, the neonatal leptin surge, ARH response to exogenous leptin, and αMSH projections to the paraventricular nucleus (PVN) in response to a high fat (HFD) or control diet (CD) in male offspring. Normoxia (NMX) and Hypoxia (HPX) offspring exhibited increased food intake when fed a HFD from 5–8 weeks post-birth; HPX offspring on the CD had increased food intake from weeks 5–7 vs. NMX offspring on a CD. HPX offspring on a HFD remained hyperphagic through 23 weeks. Body weight were the same between offspring from HPX vs. NMX dams from 4–12 weeks of age fed a CD or HFD. By 14–23 weeks of age, HPX offspring fed the CD or HFD as well as male NMX offspring fed the HFD were heavier vs. NMX offspring fed the CD. HPX offspring fed a CD exhibited increased abdominal adiposity (MRI) that was amplified by a HFD. HPX offspring fed a HFD exhibited the highest abdominal fat cytokine expression. HPX male offspring had higher plasma leptin from postnatal day (PN) 6 through 14 vs. NMX pups. HPX offspring exhibited increased basal c-Fos labeled cells in the ARH vs. NMX pups on PN16. Leptin increased c-Fos staining in the ARH in NMX but not HPX offspring at PN16. HPX offspring had fewer αMSH fibers in the PVN vs. NMX offspring on PN16. In conclusion, gestational hypoxia impacts the developing ARH resulting in hyperphagia contributing to adult obesity on a control diet and exacerbated by a HFD.

Intrauterine growth retardation promotes fetal intestinal autophagy in rats via the mechanistic target of rapamycin pathway

Intrauterine growth retardation (IUGR) impairs fetal intestinal development, and is associated with high perinatal morbidity and mortality. However, the mechanism underlying this intestinal injury is largely unknown. We aimed to investigate this mechanism through analysis of intestinal autophagy and related signaling pathways in a rat model of IUGR. Normal weight (NW) and IUGR fetuses were obtained from primiparous rats via ad libitum food intake and 50% food restriction, respectively. Maternal serum parameters, fetal body weight, organ weights, and fetal blood glucose were determined. Intestinal apoptosis, autophagy, and the mechanistic target of rapamycin (mTOR) signaling pathway were analyzed. The results indicated that maternal 50% food restriction reduced maternal serum glucose, bilirubin, and total cholesterol and produced IUGR fetuses, which had decreased body weight; blood glucose; and weights of the small intestine, stomach, spleen, pancreas, and kidney. Decreased Bcl-2 and increased Casp9 mRNA expression was observed in IUGR fetal intestines. Analysis of intestinal autophagy showed that the mRNA expression of WIPI1, MAP1LC3B, Atg5, and Atg14 was also increased, while the protein levels of p62 were decreased in IUGR fetuses. Compared to NW fetuses, IUGR fetuses showed decreased mTOR protein levels and enhanced mRNA expression of ULK1 and Beclin1 in the small intestine. In summary, the results indicated that maternal 50% food restriction on gestational days 10–21 reduced maternal serum glucose, bilirubin, and total cholesterol contents, and produced IUGR fetuses that had low blood glucose and reduced small intestine weight. Intestinal injury of IUGR fetuses caused by maternal food restriction might be due to enhanced apoptosis and autophagy via the mTOR signaling pathway.

Long-Term Effects of Prenatal Exposure to Undernutrition on Cannabinoid Receptor-Related Behaviors: Sex and Tissue-Specific Alterations in the mRNA Expression of Cannabinoid Receptors and Lipid Metabolic Regulators

Maternal malnutrition causes long-lasting alterations in feeding behavior and energy homeostasis in offspring. It is still unknown whether both, the endocannabinoid (eCB) machinery and the lipid metabolism are implicated in long-term adaptive responses to fetal reprogramming caused by maternal undernutrition. We investigated the long-term effects of maternal exposure to a 20% standard diet restriction during preconceptional and gestational periods on the metabolically-relevant tissues hypothalamus, liver, and perirenal fat (PAT) of male and female offspring at adulthood. The adult male offspring from calorie-restricted dams (RC males) exhibited a differential response to the CB1 antagonist AM251 in a chocolate preference test as well as increased body weight, perirenal adiposity, and plasma levels of triglycerides, LDL, VLDL, bilirubin, and leptin. The gene expression of the cannabinoid receptors Cnr1 and Cnr2 was increased in RC male hypothalamus, but a down-expression of most eCBs-metabolizing enzymes (Faah, Daglα, Daglβ, Mgll) and several key regulators of fatty-acid β-oxidation (Cpt1b, Acox1), mitochondrial respiration (Cox4i1), and lipid flux (Pparγ) was found in their PAT. The female offspring from calorie-restricted dams exhibited higher plasma levels of LDL and glucose as well as a reduction in chocolate and caloric intake at post-weaning periods in the feeding tests. Their liver showed a decreased gene expression of Cnr1, Pparα, Pparγ, the eCBs-degrading enzymes Faah and Mgll, the de novo lipogenic enzymes Acaca and Fasn, and the liver-specific cholesterol biosynthesis regulators Insig1 and Hmgcr. Our results suggest that the long-lasting adaptive responses to maternal caloric restriction affected cannabinoid-regulated mechanisms involved in feeding behavior, adipose β-oxidation, and hepatic lipid and cholesterol biosynthesis in a sex-dependent manner.

Cross-fostering: Elucidating the effects of gene×environment interactions on phenotypic development

Cross-fostering of litters from soon after birth until weaning is a valuable tool to study the ways in which gene×environment interactions program the development of neural, physiological and behavioral characteristics of mammalian species. In laboratory mice and rats, the primary focus of this review, cross-fostering of litters between mothers of different strains or treatment groups (intraspecific) or between mothers of different species (interspecific) has been conducted over the past 9 decades. Areas of particular interest have included maternal effects on emotionality, social preferences, responses to stressful stimulation, nutrition and growth, blood pressure regulation, and epigenetic effects on brain development and behavior. Results from these areas of research highlight the critical role of the postnatal maternal environment in programming the development of offspring phenotypic characteristics. In addition, experimental paradigms that have included cross-fostering have permitted investigators to tease apart prenatal versus postnatal effects of various treatments on offspring development and behavior.

Maternal Triclosan consumption alters the appetite regulatory network on Wistar rat offspring and predispose to metabolic syndrome in the adulthood

The objectives of this study were to evaluate the effects of maternal oral exposure to the antibacterial Triclosan (TCS) during gestation and lactation on the metabolic status of the adult offspring and on the expression of main genes controlling the appetite regulatory network. Pregnant rats were fed ad-libitum with ground food + TCS (1 mg/kg) from day 14 of gestation to day 20 of lactation (n=3) or ground food (n=3). After litter reduction, 12 males and 12 females born from the TCS exposed rats (TCS, n=24) or not (Control, n=24) were used to evaluate monthly body weight, food intake, plasma levels of cholesterol, glucose and triglycerides, and the hypothalamic mRNA expression of agouti-related protein (Agrp), neuropeptide Y (Npy) and propiomelanocortin (Pomc). Body weight for rats in the TCS group was 12.5% heavier for males at 4 months (p<0.001) and 19% heavier for females at 8 months (p=0.01). Food intake was significantly higher for rats in the TCS group at 5 months of age (p<0.01). Cholesterol and glucose levels were significantly higher for rats in the TCS group at 8 months (p<0.05). mRNA expression of Npy and Agrp were significantly increased in hypothalami of rats in the TCS group at 2 months for males or 8 months for females (p<0.05). In conclusion, low doses of oral TCS consumption by the pregnant and lactating dam increase the hypothalamic expression of the orexigenic neuropeptides Npy and Agrp in the offspring and alter their metabolic status during adulthood, resembling development of the metabolic syndrome.

Prenatal food restriction induces poor-quality articular cartilage in female rat offspring fed a post-weaning high-fat diet and its intra-uterine programming mechanisms

Epidemiological data show that osteoarthritis (OA) is significantly associated with lower birth weight, and that OA may be a type of fetal-originated adult disease. The present study aimed to investigate the prenatal food-restriction (PFR) effect on the quality of articular cartilage in female offspring to explore the underlying mechanisms of fetal-originated OA. Maternal rats were fed a restricted diet from gestational day (GD) 11 to 20 to induce intra-uterine growth retardation. Female fetuses and female adult offspring fed a post-weaning high-fat diet were killed at GD20 and postnatal week 24, respectively. Serum and knee cartilage samples from fetuses and adult female offspring were collected and examined for cholesterol metabolism and histology. Fetal serum corticosterone and insulin-like growth factor-1 (IGF-1) in the PFR group were lower than those of the control, but the serum cholesterol level was not changed. The lower expression of IGF-1 in the PFR group lasted into adulthood. The expression of extracellular matrix (ECM) genes, including type II collagen, aggrecan and cholesterol efflux genes including liver X receptor, were significantly induced, but the ATP-binding-cassette transporter A1 was unchanged. PFR could induce a reduction in ECM synthesis and impaired cholesterol efflux in female offspring, and eventually led to poor quality of articular cartilage and OA.

Bone marrow mesenchymal stem cells of the intrauterine growth-restricted rat offspring exhibit enhanced adipogenic phenotype

OBJECTIVE

Although intrauterine nutritional stress is known to result in offspring obesity and the metabolic phenotype, the underlying cellular/molecular mechanisms remain incompletely understood. We tested the hypothesis that compared with the controls, the bone marrow-derived mesenchymal stem cells (BMSCs) of the intrauterine growth-restricted (IUGR) offspring exhibit a more adipogenic phenotype.

METHODS

A well-established rat model of maternal food restriction (MFR), that is, 50% global caloric restriction during the later-half of pregnancy and ad libitum diet following birth that is known to result in an obese offspring with a metabolic phenotype was used. BMSCs at 3 weeks of age were isolated, and then molecularly and functionally profiled.

RESULTS

BMSCs of the intrauterine nutritionally-restricted offspring demonstrated an increased proliferation and an enhanced adipogenic molecular profile at miRNA, mRNA and protein levels, with an overall up-regulated PPARγ (miR-30d, miR-103, PPARγ, C/EPBα, ADRP, LPL, SREBP1), but down-regulated Wnt (LRP5, LEF-1, β-catenin, ZNF521 and RUNX2) signaling profile. Following adipogenic induction, compared with the control BMSCs, the already up-regulated adipogenic profile of the MFR BMSCs, showed a further increased adipogenic response.

CONCLUSIONS

Markedly enhanced adipogenic molecular profile and increased cell proliferation of MFR BMSCs suggest a possible novel cellular/mechanistic link between the intrauterine nutritional stress and offspring metabolic phenotype. This provides new potential predictive and therapeutic targets against these conditions in the IUGR offspring.

Changes of blood pressure, abdominal visceral fat tissue and gene expressions in fetal programming induced rat model after amlodipine-losartan combination treatment

Background

There are a number of complications that can occur if there is under-nutrition during pregnancy followed by a period of rapid catch-up growth, including a higher chance of adult obesity, insulin resistance and hypertriglyceridemia. The purposes of this study were to investigate the effects of fetal under-nutrition during late pregnancy and lactation on blood pressure, visceral fat tissue, gene expressions and to evaluate changes after amlodipine- losartan combination treatment.

Methods

The rats were divided into three groups: the control (C) group, the food restriction (FR: 50 % food restricted diet) group, and the CX group, which was treated with Cozaar XQ (amlodipine- losartan combination drug) in FR rats from postnatal 4 to 20 weeks. Masson’s trichrome staining was performed in the heart tissues. The amount of abdominal visceral fat tissues was measured. Western blot analysis such as angiotensin converting enzyme (ACE), angiotensin II receptor type IA (ATIA), troponin I (Tn I) and endothelial nitric oxide synthase (eNOS) were performed.

Results

Body weights were significantly higher in the FR group compared with the C group at weeks 8 and 20 and lower in the CX group at week 20. Blood pressure was significantly higher in the FR group compared with the C group at week 20 and lower in the CX group at weeks 12 and 20. The amount of abdominal visceral fat was significantly higher in the FR group compared with the C group at weeks 8, 12 and 20 and significantly lower in the CX group at weeks 16 and 20. Protein expression of ATIA and eNOS were significantly reduced in the CX group at weeks 16 and 20. ACE was significantly reduced in the CX group at week 20 and Tn I was significantly reduced in the CX group at week 16.

Conclusions

When there is fetal under-nutrition during pregnancy, it leads to obesity, high blood pressure, hypertriglyceridemia and several gene changes in offspring. Amlodipine-losartan combination treatment was able to lower obesity, hypertension, hypertriglyceridemia and several gene changes in rats suffering from fetal under-nutrition during pregnancy.

The Programming Power of the Placenta

Size at birth is a critical determinant of life expectancy, and is dependent primarily on the placental supply of nutrients. However, the placenta is not just a passive organ for the materno-fetal transfer of nutrients and oxygen. Studies show that the placenta can adapt morphologically and functionally to optimize substrate supply, and thus fetal growth, under adverse intrauterine conditions. These adaptations help meet the fetal drive for growth, and their effectiveness will determine the amount and relative proportions of specific metabolic substrates supplied to the fetus at different stages of development. This flow of nutrients will ultimately program physiological systems at the gene, cell, tissue, organ, and system levels, and inadequacies can cause permanent structural and functional changes that lead to overt disease, particularly with increasing age. This review examines the environmental regulation of the placental phenotype with particular emphasis on the impact of maternal nutritional challenges and oxygen scarcity in mice, rats and guinea pigs. It also focuses on the effects of such conditions on fetal growth and the developmental programming of disease postnatally. A challenge for future research is to link placental structure and function with clinical phenotypes in the offspring.

Decreased liver triglyceride content in adult rats exposed to protein restriction during gestation and lactation: role of hepatic triglyceride utilization

We have previously demonstrated that protein restriction throughout gestation and lactation reduces liver triglyceride content in adult rat offspring. However, the mechanisms mediating the decrease in liver triglyceride content are not understood. The aim of the current study was to use a new group of pregnant animals and their offspring and determine the contribution of increased triglyceride utilization via the hepatic fatty-acid oxidation and triglyceride secretory pathways to the reduction in liver triglyceride content. Pregnant Sprague-Dawley rats received either a control or a low protein diet throughout pregnancy and lactation. Pups were weaned onto laboratory chow on day 28 and killed on day 65. Liver triglyceride content was reduced in male, but not female, low-protein offspring, both in the fed and fasted states. The reduction was accompanied by a trend towards higher liver carnitine palmitoyltransferase-1a activity, suggesting increased fatty-acid transport into the mitochondrial matrix. However, medium-chain acyl coenzyme A dehydrogenase activity within the mitochondrial matrix, expression of nuclear peroxisome proliferator activated receptor-α, and plasma levels of β-hydroxybutyrate were similar between low protein and control offspring, indicating a lack of change in fatty-acid oxidation. Hepatic triglyceride secretion, assessed by blocking peripheral triglyceride utilization and measuring serum triglyceride accumulation rate, and the activity of microsomal transfer protein, were similar between low protein and control offspring. Because enhanced triglyceride utilization is not a significant contributor, the decrease in liver triglyceride content in male low-protein offspring is likely due to alterations in liver fatty-acid transport or triglyceride biosynthesis.

Proteomic Analysis of One-carbon Metabolism-related Marker in Liver of Rat Offspring

Maternal food intake has a significant effect on the fetal environment, and an inadequate maternal diet may result in intrauterine growth restriction. Intrauterine growth restriction newborn rat pups nursed by normal diet-fed dams exhibited rapid catch-up growth, which plays a critical role in the risk for metabolic and cardiovascular disease in later life. Specifically, one-carbon metabolism in the liver plays a critical role in placental and fetal growth. Impaired functioning of one-carbon metabolism is associated with increased homocysteine levels. In this study, we applied a comprehensive proteomic approach to identify differential expression of proteins related to one-carbon metabolism in the livers of rat offspring as an effect of maternal food restriction during gestation. Data are available via ProteomeXchange with identifier PXD002578. We determined that betaine-homocysteine S-methyltransferase 1, methylenetetrahydrofolate dehydrogenase 1, and ATP synthase subunit beta mitochondrial (ATP5B) expression levels were significantly reduced in the livers of rat offspring exposed to maternal food restriction during gestation compared with in the offspring of rats fed a normal diet (p < 0.05). Moreover, the expression levels of betaine-homocysteine S-methyltransferase 1, methylenetetrahydrofolate dehydrogenase 1, and ATP synthase subunit beta mitochondrial were negatively correlated with serum homocysteine concentration in male offspring exposed to maternal food restriction during gestation and normal diet during lactation. However, in female offspring only expression levels of methylenetetrahydrofolate dehydrogenase 1 were negatively correlated with homocysteine concentration. This study shows that maternal food restriction during late gestation and normal diet during lactation lead to increased homocysteine concentration through disturbance of one-carbon metabolism in the livers of male offspring. This suggests that male offspring have an increased gender-specific susceptibility to disease in later life through fetal programming.

Programmed regulation of rat offspring adipogenic transcription factor (PPARγ) by maternal nutrition

We determined the protein expression of adipogenic transcription factor, peroxisome proliferator-activated receptor gamma (PPARγ) and its co-repressor and co-activator complexes in adipose tissue from the obese offspring of under- and over-nourished dams. Female rats were fed either a high-fat (60% kcal) or control (10% kcal) diet before mating, and throughout pregnancy and lactation (Mat-OB). Additional dams were 50% food-restricted from pregnancy day 10 to term [intrauterine growth-restricted (IUGR)]. Adipose tissue protein expression was analyzed in newborn and adult male offspring. Normal birth weight Mat-OB and low birth weight IUGR newborns had upregulated PPARγ with variable changes in co-repressors and co-activators. As obese adults, Mat-OB and IUGR offspring had increased PPARγ with decreased co-repressor and increased co-activator expression. Nutritionally programmed increased PPARγ expression is associated with altered expression of its co-regulators in the newborn and adult offspring. Functional studies of PPARγ co-regulators are necessary to establish their role in PPARγ-mediated programmed obesity.

Intrauterine growth restriction increases the preference for palatable foods and affects sensitivity to food rewards in male and female adult rats

Clinical evidence suggests that intrauterine growth restriction (IUGR) can cause persistent changes in the preference for palatable foods. In this study, we compared food preferences, the response to food rewards, and the role of the mesolimbic dopaminergic system in feeding behavior, between IUGR and control rats. Time-mated pregnant Sprague-Dawley rats were randomly allocated to a control group (standard chow ad libitum) or a 50% food restriction (FR) group, which received 50% of the control dams׳ habitual intake. These diets were provided from gestation day 10 to the 21st day of lactation. Within 24h of birth, pups were cross-fostered and divided into four groups: Adlib/Adlib, FR/Adlib, FR/FR, Adlib/FR. Standard chow consumption was compared between all groups. Food preferences, conditioned place preference to a palatable diet, and the levels of tyrosine hydroxylase (TH) phosphorylation and D2 receptors in the nucleus accumbens were analyzed and compared between the two groups of interest: Adlib/Adlib (control) and FR/Adlib (exposed to growth restriction during the fetal period only). IUGR adult rats had a stronger preference for palatable foods, but showed less conditioned place preference to a palatable diet than controls. D2 receptors levels were lower in IUGR rats. At baseline, TH and pTH levels were higher in FR/Adlib than control males. Measurements taken after exposure to sweet foods revealed higher levels of TH and pTH in FR/Adlib than control females. These data showed that IUGR rats exhibited a preference for palatable foods, potentially due to alterations in their mesolimbic reward pathway. Additionally, the changes observed in the mesolimbic dopaminergic system of IUGR rats proved to be sex-specific. This article is part of a Special Issue entitled 1618.

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.

Effects of maternal LPS exposure during pregnancy on metabolic phenotypes in female offspring

It is increasingly recognized that intra-uterine growth restriction (IUGR) is associated with an increased risk of metabolic disorders in late life. Previous studies showed that mice exposed to LPS in late gestation induced fetal IUGR. The present study investigated the effects of maternal LPS exposure during pregnancy on metabolic phenotypes in female adult offspring. Pregnant mice were intraperitoneally injected with LPS (50 µg/kg) daily from gestational day (GD)15 to GD17. After lactation, female pups were fed with standard-chow diets (SD) or high-fat diets (HFD). Glucose tolerance test (GTT) and insulin tolerance test (ITT) were assessed 8 and 12 weeks after diet intervention. Hepatic triglyceride content was examined 12 weeks after diet intervention. As expected, maternal LPS exposure during pregnancy resulted in fetal IUGR. Although there was an increasing trend on fat mass in female offspring whose dams were exposed to LPS during pregnancy, maternal LPS exposure during pregnancy did not elevate the levels of fasting blood glucose and serum insulin and hepatic triglyceride content in female adult offspring. Moreover, maternal LPS exposure during pregnancy did not alter insulin sensitivity in adipose tissue and liver in female adult offspring. Further analysis showed that maternal LPS exposure during pregnancy did not exacerbate HFD-induced glucose tolerance and insulin resistance in female adult offspring. In addition, maternal LPS exposure during pregnancy did not aggravate HFD-induced elevation of hepatic triglyceride content in female adult offspring. In conclusion, LPS-induced IUGR does not alter metabolic phenotypes in adulthood.

Maternal undernutrition induces premature reproductive senescence in adult female rat offspring

OBJECTIVE

To determine the effects of maternal undernutrition (MUN) on the reproductive axis of aging offspring.

DESIGN

Animal (rat) study.

SETTING

Research laboratory.

ANIMAL(S)

Female Sprague-Dawley rats.

INTERVENTION(S)

Food restriction during the second half of pregnancy in rats.

MAIN OUTCOME MEASURE(S)

Circulating gonadotropins, antimüllerian hormone (AMH), ovarian morphology, estrous cyclicity, and gene expression studies in the hypothalamus and ovary in 1-day-old (P1) and aging adult offspring.

RESULT(S)

Offspring of MUN dams had low birth weight (LBW) and by adult age developed obesity. In addition, 80% of adult LBW offspring had disruption of estrous cycle by 8 months of age, with the majority of animals in persistent estrous. Ovarian morphology was consistent with acyclicity, with ovaries exhibiting large cystic structures and reduced corpora lutea. There was an elevation in circulating T, increased ovarian expression of enzymes involved in androgen synthesis, an increase in plasma LH/FSH levels, a reduction in E2 levels, and no changes in AMH in adult LBW offspring compared with in control offspring. Hypothalamic expression of leptin receptor (ObRb), estrogen receptor-α (ER-α), and GnRH protein was altered in an age-dependent manner with increased ObRb and ER-α expression in P1 LBW hypothalami and a reversal of this expression pattern in adult LBW hypothalami.

CONCLUSION(S)

Our data indicate that the maternal nutritional environment programs the reproductive potential of the offspring through alteration of the hypothalamic-pituitary-gonadal axis. The premature reproductive senescence in LBW offspring could be secondary to the development of obesity and hyperleptinemia in these animals in adult life.

Mechanism of programmed obesity: altered central insulin sensitivity in growth-restricted juvenile female rats

Intrauterine growth-restricted (IUGR) offspring are at increased risk of adult obesity, as a result of changes in energy balance mechanisms. We hypothesized that impairment of hypothalamic insulin signaling contributes to hyperphagia in IUGR offspring. Study pregnant dams were 50% food restricted from days 10 to 21 to create IUGR newborns. At 5 weeks of age, food intake was measured following intracerebroventricular (icv) injection of vehicle or insulin (10 mU) in control and IUGR pups. At 6 weeks of age, with pups in fed or fasted (48 h) states, pups received icv vehicle or insulin after which they were decapitated, and hypothalamic arcuate (ARC) nucleus dissected for RNA and protein expression. IUGR rats consumed more food than controls under basal conditions, consistent with upregulated ARC phospho AMP-activated protein kinase (pAMPK) and neuropeptide Y (NPY). Insulin acutely reduced food intake in both control and IUGR rats. Consistent with anorexigenic stimulation, central insulin decreased AMP-activated protein kinase and NPY mRNA expression and increased proopiomelanocortin mRNA expression and pAkt, with significantly reduced responses in IUGR as compared with controls. Despite feeding, IUGR offspring exhibit a persistent state of orexigenic stimulation in the ARC nucleus and relative resistance to the anorexigenic effects of icv insulin. These results suggest that impaired insulin signaling contributes to hyperphagia and obesity in IUGR offspring.

Maternal tobacco smoke increased visceral adiposity and serum corticosterone levels in adult male rat offspring

BACKGROUND

Maternal tobacco smoke (MTS) predisposes human and rat offspring to visceral obesity in early adulthood. Glucocorticoid excess also causes visceral obesity. We hypothesized that in utero MTS would increase visceral adiposity and alter the glucocorticoid pathway in young adult rats.

METHODS

We developed a novel model of in utero MTS exposure in pregnant rats by exposing them to cigarette smoke from E11.5 to term. Neonatal rats were cross-fostered to control dams and weaned to standard rat chow through young adulthood (postnatal day 60).

RESULTS

We demonstrated increased visceral adiposity (193%)*, increased visceral adipose 11-β hydroxysteroid dehydrogenase 1 mRNA (204%)*, increased serum corticosterone (147%)*, and no change in glucocorticoid receptor protein in adult male MTS rat offspring. Female rats exposed to MTS in utero demonstrated no change in visceral or subcutaneous adiposity, decreased serum corticosterone (60%)*, and decreased adipose glucocorticoid receptor protein (66%)*. *P < 0.05.

CONCLUSION

We conclude that in utero MTS exposure increased visceral adiposity and altered in the glucocorticoid pathway in a sex-specific manner. We speculate that in utero MTS exposure programs adipose dysfunction in adult male rat offspring via alteration in the glucocorticoid pathway.

Administration of saccharin to neonatal mice influences body composition of adult males and reduces body weight of females

Nutritional or pharmacological perturbations during perinatal growth can cause persistent effects on the function of white adipose tissue, altering susceptibility to obesity later in life. Previous studies have established that saccharin, a nonnutritive sweetener, inhibits lipolysis in mature adipocytes and stimulates adipogenesis. Thus, the current study tested whether neonatal exposure to saccharin via maternal lactation increased susceptibility of mice to diet-induced obesity. Saccharin decreased body weight of female mice beginning postnatal week 3. Decreased liver weights on week 14 corroborated this diminished body weight. Initially, saccharin also reduced male mouse body weight. By week 5, weights transiently rebounded above controls, and by week 14, male body weights did not differ. Body composition analysis revealed that saccharin increased lean and decreased fat mass of male mice, the latter due to decreased adipocyte size and epididymal, perirenal, and sc adipose weights. A mild improvement in glucose tolerance without a change in insulin sensitivity or secretion aligned with this leaner phenotype. Interestingly, microcomputed tomography analysis indicated that saccharin also increased cortical and trabecular bone mass of male mice and modified cortical bone alone in female mice. A modest increase in circulating testosterone may contribute to the leaner phenotype in male mice. Accordingly, the current study established a developmental period in which saccharin at high concentrations reduces adiposity and increases lean and bone mass in male mice while decreasing generalized growth in female mice.

Developmental programming of offspring obesity, adipogenesis, and appetite

A newly recognized primary cause of the obesity epidemic is the developmental programming effects of infants born to mothers with obesity or gestational diabetes, intrauterine growth-restricted newborns, and offspring exposed to environmental toxins including bisphenol A. The mechanisms which result in offspring obesity include the programming of the hypothalamic appetite pathway and adipogenic signals regulating lipogenesis. Processes include nutrient sensors, epigenetic modifications, and alterations in stem cell precursors of both appetite/satiety neurons and adipocytes which are modulated to potentiate offspring obesity. Future strategies for the prevention and therapy of obesity must address programming effects of the early life environment.

Maternal nutrition and risk of obesity in offspring: the Trojan horse of developmental plasticity

Mammalian embryos have evolved to adjust their organ and tissue development in response to an atypical environment. This adaptation, called phenotypic plasticity, allows the organism to thrive in the anticipated environment in which the fetus will emerge. Barker and colleagues proposed that if the environment in which the fetus emerges differs from that in which it develops, phenotypic plasticity may provide an underlying mechanism for disease. Epidemiological studies have shown that humans born small- or large-for-gestational-age, have a higher likelihood of developing obesity as adults. The amount and quality of food that the mother consumes during gestation influences birth weight, and therefore susceptibility of progeny to disease in later life. Studies in experimental animals support these observations, and find that obesity occurs as a result of maternal nutrient-restriction during gestation, followed by rapid compensatory growth associated with ad libitum food consumption. Therefore, obesity associated with maternal nutritional restriction has a developmental origin. Based on this phenomenon, one might predict that gestational exposure to a westernized diet would protect against future obesity in offspring. However, evidence from experimental models indicates that, like maternal dietary restriction, maternal consumption of a westernized diet during gestation and lactation interacts with an adult obesogenic diet to induce further obesity. Mechanistically, restriction of nutrients or consumption of a high fat diet during gestation may promote obesity in progeny by altering hypothalamic neuropeptide production and thereby increasing hyperphagia in offspring. In addition to changes in food intake these animals may also direct energy from muscle toward storage in adipose tissue. Surprisingly, generational inheritance studies in rodents have further indicated that effects on body length, body weight, and glucose tolerance appear to be propagated to subsequent generations. Together, the findings discussed herein highlight the concept that maternal nutrition contributes to a legacy of obesity. Thus, ensuring adequate supplies of a complete and balanced diet during and after pregnancy should be a priority for public health worldwide. This article is part of a Special Issue entitled: Modulation of Adipose Tissue in Health and Disease.

An intrauterine catch-up growth regimen increases food intake and post-natal growth in rats

Nutritional conditions during the intrauterine stage are an important developmental programming factor that can affect the growth and metabolic status during foetal development and permanently alter the phenotypes of newborn offspring and adults. This study was performed to examine the effects of intrauterine catch-up growth (IUCG) on food intake, post-natal body growth and the metabolic status of offspring and growing rats. Control pregnant rats were fed ad libitum during the entire gestation period. For the IUCG regimen, pregnant rats were fed 50% of the food of the controls from pregnancy days 4 through 11 (8 days), followed by ad libitum feeding from pregnancy days 12 through parturition. The birth weight of offspring was not affected by the IUCG regimen. At weaning, offspring from each treatment group were assigned to two groups and given either a normal diet or high-fat diet (HFD) for 12 weeks until 103 days of age. In the normal diet group, the IUCG offspring showed a 9.0% increase (P < 0.05) in total food intake, were 11.2% heavier (p < 0.05) at 103 days of age and had an 11.0% greater (p < 0.05) daily weight gain compared with control offspring. The IUCG regimen did not affect body glucose and lipid metabolism. After exposure to the HFD, the IUCG regimen has not exacerbated metabolic disorders. In conclusion, our findings suggest that the IUCG nutritional regimen during pregnancy can increase the food intake and post-natal body growth of offspring without inducing metabolic disorders such as obesity and insulin resistance. The IUCG nutritional regimen might be used to improve the food intake and post-natal body growth of domestic animals.

Short- and long-term effects of maternal perinatal undernutrition are lowered by cross-fostering during lactation in the male rat

Undernutrition exposure during the perinatal period reduces the growth kinetic of the offspring and sensitizes it to the development of chronic adult metabolic diseases both in animals and in humans. Previous studies have demonstrated that a 50% maternal food restriction performed during the last week of gestation and during lactation has both short- and long-term consequences in the male rat offspring. Pups from undernourished mothers present a decreased intrauterine (IUGR) and extrauterine growth restriction. This is associated with a drastic reduction in their leptin plasma levels during lactation, and exhibit programming of their stress neuroendocrine systems (corticotroph axis and sympatho-adrenal system) in adulthood. In this study, we report that perinatally undernourished 6-month-old adult animals demonstrated increased leptinemia (at PND200), blood pressure (at PND180), food intake (from PND28 to PND168), locomotor activity (PND187) and altered regulation of glycemia (PND193). Cross-fostering experiments indicate that these alterations were prevented in IUGR offspring nursed by control mothers during lactation. Interestingly, the nutritional status of mothers during lactation (ad libitum feeding v. undernutrition) dictates the leptin plasma levels in pups, consistent with decreased leptin concentration in the milk of mothers subjected to perinatal undernutrition. As it has been reported that postnatal leptin levels in rodent neonates may have long-term metabolic consequences, restoration of plasma leptin levels in pups during lactation may contribute to the beneficial effects of cross-fostering IUGR offspring to control mothers. Collectively, our data suggest that modification of milk components may offer new therapeutic perspectives to prevent the programming of adult diseases in offspring from perinatally undernourished mothers.

Feed your head: neurodevelopmental control of feeding and metabolism

During critical periods of development early in life, excessive or scarce nutritional environments can disrupt the development of central feeding and metabolic neural circuitry, leading to obesity and metabolic disorders in adulthood. A better understanding of the genetic networks that control the development of feeding and metabolic neural circuits, along with knowledge of how and where dietary signals disrupt this process, can serve as the basis for future therapies aimed at reversing the public health crisis that is now building as a result of the global obesity epidemic. This review of animal and human studies highlights recent insights into the molecular mechanisms that regulate the development of central feeding circuitries, the mechanisms by which gestational and early postnatal nutritional status affects this process, and approaches aimed at counteracting the deleterious effects of early over- and underfeeding.

Unlimited access to low-energy diet causes acute malnutrition in dams and alters biometric and biochemical parameters in offspring

Here we analyze the outcomes of unlimited access to a low-energy (LE) diet in dams and their offspring. At 3 weeks’ gestation, pregnant Wistar rats were divided into two groups: (1) the control group received a normoenergetic diet; and (2) the experimental group received the LE diet. In dams, lactation outcomes, food intake, body weight, plasma IGF-1, prealbumin, transferrin and retinol-binding protein levels were evaluated; in offspring, biometric and biochemical parameters and food intake were evaluated. No differences were observed during pregnancy. However, after lactation, dams that received the LE diet demonstrated significant reductions in body weight (P<0.05), plasma IGF-1 (P=0.01), prealbumin and visceral fat (P<0.001). Pups born to dams that received the LE diet demonstrated reduced body length and weight at weaning (P<0.001) and were lighter than the control animals at the end of the experimental period. Pups also demonstrated reduced plasma, low-density lipoprotein (P=0.04), triglycerides (P=0.002) and glucose levels (P<0.05), and differences were noted in visceral fat. These results indicate that feeding dams with LE diet during the reproductive period induces acute malnutrition and impairs the growth and development of offspring, as well as certain metabolic parameters.

Nutritional potential of metabolic remodelling of white adipose tissue

PURPOSE OF REVIEW

Recent findings in animals suggest that diet-related factors can programme adipose tissue features in early life and remodel white adipose tissue (WAT) towards a brown adipose tissue (BAT)-like phenotype in adulthood, while impacting on body fat content and susceptibility to obesity. The purpose of this review is to address the significance of these results and their applicability in humans.

RECENT FINDINGS

Nutritional conditions in the perinatal period influence sympathetic innervation to WAT and WAT cellularity in rodents. Leptin intake during the suckling period prevents obesity and other metabolic alterations in later life in rats through mechanisms that include increased sensitivity of adipose tissues to leptin. Recent data support the thermogenic functionality of inducible brown-like cells in rodent WAT and functional thermogenic beige adipogenesis from human progenitor cells. Diet-related factors and exercise can promote BAT activation and/or WAT-to-BAT remodelling (WAT browning) in animals.

SUMMARY

Animal studies suggest that adipose tissue health and whole body adiposity might be influenced by early life nutrition and lifestyle factors in adulthood impacting energy metabolism in adipose tissues. For this knowledge to be translated to humans, biomarkers allowing early detection of the programming status of the individual and technologies allowing measuring of the thermogenic activity of adipose tissue depots in vivo are required.

Induction of the hepatic stearoyl-CoA desaturase 1 gene in offspring after isocaloric administration of high fat sucrose diet during gestation

Adverse early nutrition leads to metabolic aberrations in adulthood. Molecular and cellular mechanisms responsible are emerging; specific nutritional causes remain unclarified. We investigated gestational dietary intake and its influences on metabolism in offspring. Three groups of pregnant Sprague-Dawley rats were fed either AIN93G standard diet as control, isocaloric high fat sucrose diet or calorie restriction diet (50% of control) until delivery. All dams were fed control diet ad libitum during lactation. Offsprings’ metabolic parameters were assessed at three weeks. Visceral fat and plasma triglycerides of high fat sucrose diet offspring were significantly higher than those of control diet and calorie restriction diet offspring. Plasma leptin level was higher in high fat sucrose diet than control offspring. Conversely, plasma adiponectin was lower in high fat sucrose diet and calorie restriction diet offspring compared to controls. Significant inductions of hepatic mRNA expression of stearoyl-CoA desaturase1 and Δ-5 desaturase genes, were observed in high fat sucrose diet and calorie restriction diet offspring. Gestational high sugar and fat intake even without over energy intake would be more detrimental to metabolisms of offspring compared to calorie restriction.