Suboptimal maternal nutrition, during early fetal liver development, promotes lipid accumulation in the liver of obese offspring.

Maternal nutrition during the period of early organ development can modulate the offspring's ability to metabolise excess fat as young adults when exposed to an obesogenic environment. This study examined the hypothesis that exposing offspring to nutrient restriction coincident with early hepatogenesis would result in endocrine and metabolic adaptations that subsequently lead to increased ectopic lipid accumulation within the liver. Pregnant sheep were fed either 50 or 100% of total metabolisable energy requirements from 30 to 80 days gestation and 100% thereafter. At weaning, offspring were made obese, and at ~1 year of age livers were sampled. Lipid infiltration and molecular indices of gluconeogenesis, lipid metabolism and mitochondrial function were measured. Although hepatic triglyceride accumulation was not affected by obesity per se, it was nearly doubled in obese offspring born to nutrient-restricted mothers. This adaptation was accompanied by elevated gene expression for peroxisome proliferator-activated receptor γ (PPARG) and its co-activator PGC1α, which may be indicative of changes in the rate of hepatic fatty acid oxidation. In contrast, maternal diet had no influence on the stimulatory effect of obesity on gene expression for a range of proteins involved in glucose metabolism and energy balance including glucokinase, glucocorticoid receptors and uncoupling protein 2. Similarly, although gene expressions for the insulin and IGF1 receptors were suppressed by obesity they were not influenced by the prenatal nutritional environment. In conclusion, excess hepatic lipid accumulation with juvenile obesity is promoted by suboptimal nutrition coincident with early development of the fetal liver.

Influence of prenatal nutrition and obesity on tissue specific fat mass and obesity-associated (FTO) gene expression.

The recent discovery of an association between body composition, energy intake and the fat mass and obesity-associated (FTO) gene represents a promising new therapeutic target in obesity prevention. In a well, pre-established large animal model, we investigated the regulation of FTO gene expression under conditions either leading to obesity or increased risk of obesity related disorders: i) a sedentary 'Western' lifestyle and ii) prenatal exposure to nutrient restriction. Pregnant sheep were either fed to fully meet their nutritional requirements throughout gestation or 50% of this amount from early-to-mid gestation. Following weaning, offspring were either made obese through exposure to a sedentary obesogenic environment or remained lean. A significant positive relationship between placental FTO gene expression and fetal weight was found at 110 days gestation. In both the newborn and adult offspring, the hypothalamus was the major site of FTO gene expression. Hypothalamic FTO gene expression was upregulated by obesity and was further increased by prenatal nutrient restriction. Importantly, we found a strong negative relationship between the hypothalamic FTO gene expression and food intake in lean animals only that may imply FTO as a novel controller of energy intake. In contrast, FTO gene expression in the heart was downregulated in obese offspring born to nutrient restricted mothers. In addition, FTO gene expression was unaffected by obesity or prenatal diet in insulin-dependent tissues, where it changed with age possibly reflecting adaptations in cellular energetic activity. These findings extend information gained from human epidemiology and provide new insights into the regulation of in vivo energy metabolism to prevent obesity.

Maternal parity and its effect on adipose tissue deposition and endocrine sensitivity in the postnatal sheep.

Maternal parity influences size at birth, postnatal growth and body composition with firstborn infants being more likely to be smaller with increased fat mass, suggesting that adiposity is set in early life. The precise effect of parity on fat mass and its endocrine sensitivity remains unclear and was, therefore, investigated in the present study. We utilised an established sheep model in which perirenal-abdominal fat mass (the major fat depot in the neonatal sheep) increases approximately 10-fold over the first month of life and focussed on the impact of parity on glucocorticoid sensitivity and adipokine expression in the adipocyte. Twin-bearing sheep of similar body weight and adiposity that consumed identical diets were utilised, and maternal blood samples were taken at 130 days of gestation. One offspring from each twin pair was sampled at 1 day of age, coincident with the time of maximal recruitment of uncoupling protein 1 (UCP1), whilst its sibling was sampled at 1 month, when UCP1 had disappeared. Plasma leptin was lower in nulliparous mothers than in multiparous mothers, and offspring of nulliparous mothers possessed more adipose tissue with increased mRNA abundance of leptin, glucocorticoid receptor and UCP2, adaptations that persisted up to 1 month of age when gene expression for interleukin-6 and adiponectin was also raised. The increase in fat mass associated with firstborn status is therefore accompanied by a resetting of the leptin and glucocorticoid axis within the adipocyte. Our findings emphasise the importance of parity in determining adipose tissue development and that firstborn offspring have an increased capacity for adipogenesis which may be critical in determining later adiposity.

Effect of maternal nutrient restriction from early to midgestation on cardiac function and metabolism after adolescent-onset obesity.

Maternal nutrient restriction (NR) from early to midgestation has marked effects on endocrine sensitivity and organ function of the resulting offspring. We hypothesized that early NR may reset the expression profile of genes central to myocardial energy metabolism, influencing ectopic lipid deposition and cardiac function in the obese adult offspring. NR offspring were exposed to an "obesogenic" environment, and their cardiac function and molecular indexes of myocardial energy metabolism were assessed to explore the hypothesis that an obese individual's risk of heart disease may be modified after maternal NR. Pregnant sheep were fed 100% (control) or 50% (NR) energy requirement from days 30 to 80 of gestation and 100% energy requirement thereafter. At weaning, offspring were exposed to an obesogenic environment or remained lean. At approximately 1 yr of age, the hemodynamic response of these offspring to hypotension, together with left ventricular expression profiles of fatty acid-binding protein 3 (FABP3), peroxisome proliferator-activated receptor-gamma (PPARgamma) and its coactivator (PGC)-1alpha, acetyl-CoA carboxylase (ACC), AMP-activated protein kinase (AMPK)-alpha(2), and voltage-dependent anion channel 1 (VDAC1), was determined. Obesity produced left ventricular hypertrophy in all animals, with increased ectopic (myocardial) lipid in NR offspring. Obesity per se significantly reduced myocardial transcript expression of PGC-1alpha, AMPKalpha(2), VDAC1, and ACC and increased expression of PPARgamma and FABP3. However, although NR animals were similarly obese, their transcript expression of ACC, PPARgamma, and FABP3 was similar to that of lean animals, indicating altered cardiac energy metabolism. Indeed, blunted tachycardia and an amplified inotropic response to hypotension characterized cardiac function in obese NR offspring. The results suggest that maternal NR during early organogenesis can precipitate an altered myocardial response to hypotension and increased myocardial lipid deposition in the adult offspring after adolescent-onset obesity, potentially rendering these individuals more at risk of early heart failure as they age.

Maternal nutrient restriction between early and midgestation and its impact upon appetite regulation after juvenile obesity.

The impact of maternal nutrient restriction during early-to-midgestation, a period coinciding with early fetal brain development, on appetite regulation and energy balance in the offspring after juvenile obesity was examined. Pregnant sheep were either fed to meet fully their nutritional requirements throughout gestation or 50% of this amount between 30 and 80 d gestation. After weaning, offspring were either made obese through exposure to a sedentary obesogenic environment or remained lean. Maternal nutrient restriction had no effect on birth weight or subsequent growth. At 1 wk of age, only, gene expression for neuropeptide Y in the hypothalamus was reduced in nutrient-restricted offspring. By 1 yr of age, all O animals had increased plasma leptin, nonesterified fatty acids, and insulin, with the latter effect amplified in NR offspring. Fasting plasma glucose, triglycerides, and cortisol were unaffected by obesity. The entrained reduction in physical activity that led to obesity persisted when all animals were maintained within individual pens. However, NRO offspring exhibited reduced daily food intake and were, therefore, no longer in positive "energy balance." This adaptation was accompanied by elevated hypothalamic gene expression for the melanocortin-4 and insulin receptors, AMP-activated kinase, and acetyl coenzyme A carboxylase alpha. In conclusion, nutrient restriction specifically targeted over the period of early fetal brain development contributes to a profoundly different adaptation in energy balance after juvenile obesity. The extent to which this adaptive response may benefit the offspring or result in an exacerbated risk of type 2 diabetes remains to be established.

Effects of maternal cold exposure and nutrient restriction on the ghrelin receptor, the GH-IGF axis, and metabolic regulation in the postnatal ovine liver.

Maternal cold exposure of pregnant sheep promotes fetal growth, whereas nutrient restriction (NR) can reverse this effect. The present study was designed to establish whether cold exposure induced by winter shearing of the mother at 70 days gestation (term=147 days), with or without NR (induced by a 50% reduction in maternal food intake from 110 days gestation), has specific effects on mRNA abundance of hepatic genes related to growth and liver energy metabolism that could regulate postnatal body and liver growth. Measurements of hepatic gene expression for the GH secretagog receptor-1a (GHSR-1A), peroxisome proliferator-activated receptor (PPAR)alpha, phosphoenolpyruvate carboxykinase (PEPCK), and glucose-6-phosphatase activity together with glycogen content were made in the livers of offspring at 1 and 30 days of age. Maternal NR reduced liver mass at day 1, whereas offspring of cold-exposed mothers had larger livers at day 30 irrespective of maternal diet. Cold exposure resulted in the up-regulation of GHSR-1A mRNA abundance and reduced glucose-6-phosphatase activity at 1, but not 30 days of age, whereas IGF-II mRNA was decreased at 1 and 30 days. PPARalpha mRNA abundance was enhanced, while PEPCK was reduced in 30-day old offspring of cold-exposed mothers. NR caused reductions in IGF-I mRNA and, at 1-day postnatal age, down-regulated GHR, while, at 30 days, reduced GHSR-1A gene expression and hepatic glycogen content. In conclusion, we have shown that maternal cold exposure and NR have different effects on the hepatic GH-IGF and metabolic axis that may contribute to changes in liver growth over the first month of life.

Ontogeny and nutritional programming of mitochondrial proteins in the ovine kidney, liver and lung.

This study investigated the developmental and nutritional programming of two important mitochondrial proteins, namely voltage-dependent anion channel (VDAC) and cytochrome c, in the sheep kidney, liver and lung. The effect of maternal nutrient restriction between early and mid-gestation (i.e. 28- to 80-day gestation, the period of maximal placental growth) on the abundance of these proteins was also examined in fetal and juvenile offspring. Fetuses were sampled at 80 and 140 days of gestation (term approximately 147 days), and postnatal animals at 1 and 30 days and 6 months of age. The abundance of VDAC peaked at 140 days of gestation in the lung, compared with 1 day after birth in the kidney and liver, whereas cytochrome c abundance was greatest at 140 days of gestation in the liver, 1 day after birth in the kidney and 6 months of age in lungs. This differential ontogeny in mitochondrial protein abundance between tissues was accompanied with very different tissue-specific responses to changes in maternal food intake. In the liver, maternal nutrient restriction only increased mitochondrial protein abundance at 80 days of gestation, compared with no effect in the kidney. In contrast, in the lung mitochondrial protein, abundance was raised near to term, whereas VDAC abundance was decreased by 6 months of age. These findings demonstrate the tissue-specific nature of mitochondrial protein development that reflects differences in functional adaptation after birth. The divergence in mitochondrial response between tissues to maternal nutrient restriction early in pregnancy further reflects these differential ontogenies.

Nutritional manipulation between early to mid-gestation: effects on uncoupling protein-2, glucocorticoid sensitivity, IGF-I receptor and cell proliferation but not apoptosis in the ovine placenta.

In sheep, modest maternal nutrient restriction (NR) over the period of rapid placental growth restricts placentome growth and results in offspring in which glucocorticoid action is enhanced. Therefore, this study investigated the placental effects of early to mid-gestational NR on glucocorticoid receptor (GR), 11beta-hydroxysteroid dehydrogenase type 2 (11betaHSD2), uncoupling protein-2 (UCP2), and IGF type-I receptor (IGF-IR) mRNA abundance together with cell proliferation and apoptosis as determined histologically, and the mitochondrial proteins voltage-dependent anion channel and cytochrome c that are involved in apoptosis. Placenta was sampled at 80 and 140 days gestation (dGA; term ~147 dGA). NR was imposed between 28 and 80 days gestation when control and nutrient-restricted groups consumed 150 or 60% respectively of their total metabolizable energy requirements. All mothers were then fed to requirements up to term. Total fetal placentome weights were decreased by NR at 80 dGA but were heavier at 140 dGA following 60 days of nutritional rehabilitation. GR and UCP2 mRNA abundance increased whilst 11betaHSD2 mRNA decreased with gestational age. NR persistently up-regulated GR and UCP2 mRNA abundance. 11betaHSD2 mRNA was reduced by NR at 80 dGA but increased near to term. IGF-IRmRNA abundance was only decreased at 80 dGA. Placental apoptosis and mitochondrial protein abundance were unaffected by NR, whereas cell proliferation was markedly reduced. In conclusion, placental UCP2 and local glucocorticoid action are affected by the gestational nutritional status and may result in the offspring showing enhanced glucocorticoid sensitivity, thereby predisposing them to disease in later life.

Maternal nutrient restriction in early pregnancy programs hepatic mRNA expression of growth-related genes and liver size in adult male sheep.

The liver is a major metabolic and endocrine organ of critical importance in the regulation of growth and metabolism. Its function is determined by a complex interaction of nutritionally regulated counter-regulatory hormones. The extent to which hepatic endocrine sensitivity can be programed in utero and whether the resultant adaptations persist into adulthood is unknown and was therefore the subject of this study. Young adult male sheep born to mothers that were fed either a control diet (i.e.100% of total live weight-maintenance requirements) throughout gestation or 50% of that intake (i.e. nutrient restricted (NR)) from 0 to 95 days gestation and thereafter 100% of requirements (taking into account increasing fetal mass) were entered into the study. All mothers gave birth normally at term, the singleton offspring were weaned at 16 weeks, and then reared at pasture until 3 years of age when their livers were sampled. NR offspring were of similar birth and body weights at 3 years of age when they had disproportionately smaller livers than controls. The abundance of mRNA for GH, prolactin, and IGF-II receptors, plus hepatocyte growth factor and suppressor of cytokine signaling-3 were all lower in livers of NR offspring. In contrast, the abundance of the mitochondrial protein voltage-dependent anion channel and the pro-apoptotic factor Bax were up regulated relative to controls. In conclusion, maternal nutrient restriction in early gestation results in adult offspring with smaller livers. This may be mediated by alterations in both hepatic mitogenic and apoptotic factors.

SETA is a multifunctional adapter protein with three SH3 domains that binds Grb2, Cbl, and the novel SB1 proteins.

Expression of the src homology 3 (SH3)-encoding, expressed in tumorigenic astrocytes (SETA) gene is associated with astrocyte transformation in culture and tumors in the adult brain. SETA binds to the apoptosis regulator apoptosis-linked gene 2 (ALG-2) interacting protein 1 (AIP1), and modulates apoptosis in astrocytes. The predicted protein structure of SETA revealed two SH3 domains, while related proteins were reported to have three. Here we report the identification of an additional SH3 domain N-terminal to the previously identified SETA sequence. Yeast two-hybrid screening of a p53(-/-) astrocyte cDNA library with this SH3 domain identified a novel gene, SETA binding protein 1 (SB1), with 55% amino acid identity to the renal tumor antigen, NY-REN-45. In vitro confrontation and co-immunoprecipitation experiments confirmed the binding of SB1 to SETA. Evidence that SETA binds to the CD2 protein, the proto-oncogene c-Cbl, and the signal transduction molecule Grb2, and can dimerize via its C-terminal coiled coil (CC) domain is also presented.