Substitution of starch for palm oil during gestation: impact on offspring survival and hepatic gene expression in the pig.

Piglet neonatal mortality rates are high (~20%), so nutritional strategies to reduce this are highly desirable. Maternal fat substitution (FS) may promote the preweaning survival of piglets by improving their energy status. Therefore, the aim of the present study was to investigate the effects of FS throughout pregnancy on offspring viability, together with the gene expression of stress-related markers in the liver. Sixteen pregnant sows were randomly allocated to one of two isocaloric diets, control (C) or FS in the form of palm oil, fed from 0 to 110 days gestation. Glucose tolerance was examined on Day 108. Median and low birthweight offspring were allocated to tissue sampling at either 7 days or 6 months postnatal age. In response to a glucose tolerance test, FS sows exhibited a raised glucose area under the curve with no change in basal glucose. Average piglet mortality (up to Day 28) was increased fourfold in the FS group, with surviving median-sized piglets exhibiting significantly lower fatty acid binding protein 1 (FABP1) expression at 7 days. There were no effects on the abundance of any other stress- or metabolic-related genes examined. Thus, this study demonstrates that maternal FS throughout gestation causes maternal glucose intolerance that may be linked to the observed increase in piglet mortality. However, the surviving offspring do not exhibit any detectable differences in postnatal growth or hepatic gene profile in later life.

Suboptimal maternal nutrition during early fetal kidney development specifically promotes renal lipid accumulation following juvenile obesity in the offspring.

Reduced maternal food intake between early-to-mid gestation results in tissue-specific adaptations in the offspring following juvenile-onset obesity that are indicative of insulin resistance. The aim of the present study was to establish the extent to which renal ectopic lipid accumulation, as opposed to other markers of renal stress, such as iron deposition and apoptosis, is enhanced in obese offspring born to mothers nutrient restricted (NR) throughout early fetal kidney development. Pregnant sheep were fed either 100% (control) or NR (i.e. fed 50% of their total metabolisable energy requirement from 30-80 days gestation and 100% at all other times). At weaning, offspring were made obese and, at approximately 1 year, kidneys were sampled. Triglyceride content, HIF-1α gene expression and the protein abundance of the outer-membrane transporter voltage-dependent anion-selective channel protein (VDAC)-I on the kidney cortex were increased in obese offspring born to NR mothers compared with those born to controls, which exhibited increased iron accumulation within the tubular epithelial cells and increased gene expression of the death receptor Fas. In conclusion, suboptimal maternal nutrition coincident with early fetal kidney development results in enhanced renal lipid deposition following juvenile obesity and could accelerate the onset of the adverse metabolic, rather than cardiovascular, symptoms accompanying the metabolic syndrome.

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.

The conflicting effects of maternal nutrient restriction and early-life obesity on renal health.

Epidemiological and animal studies have demonstrated that early-life nutrition alters the metabolic responses and generates structural changes in complex tissues, such as the kidneys, which may lead to a reduction in the offspring lifespan. Independently, obesity induces a spontaneous low-grade chronic inflammatory response by modulating several of the major metabolic pathways that ultimately compromise long-term renal health. However, the combined effects of maternal nutrition and early-life obesity in the development of renal diseases are far from conclusive. Previous results, using the ovine model, demonstrated that the combination of a reduction in fetal nutrition and juvenile obesity induced a series of adaptations associated with severe metabolic syndrome in the heart and adipose tissue. Surprisingly, exposure to an obesogenic environment in the kidney of those offspring produced an apparent reduction in glomerulosclerosis in relation to age- and weight-matched controls. However, this reduction in cellular apoptosis was accompanied by a rise in glomerular filtration rate and blood pressure of equal intensity when compared with obese controls. The intention of this review is to explain the adaptive responses observed in this model, based on insights into the mechanism of renal fetal programming, and their potential interactions with some of the metabolic changes produced by obesity.

Maternal nutrient restriction during late gestation and early postnatal growth in sheep differentially reset the control of energy metabolism in the gastric mucosa.

Fetal growth restriction followed by accelerated postnatal growth contributes to impaired metabolic function in adulthood. The extent to which these outcomes may be mediated centrally within the hypothalamus, as opposed to in the periphery within the digestive tract, remains unknown. In a sheep model, we achieved intrauterine growth restriction experimentally by maternal nutrient restriction (R) that involved a 40% reduction in food intake through late gestation. R offspring were then either reared singly to accelerate postnatal growth (RA) or as twins and compared with controls also reared singly. From weaning, all offspring were maintained indoors until adulthood. A reduced litter size accelerated postnatal growth for only the first month of lactation. Independently from postnatal weight gain and later fat mass, R animals developed insulin resistance as adults. However, restricted accelerated offspring compared with both the control accelerated and restricted restricted offspring ate less and had higher fasting plasma leptin as adults, an adaptation which was accompanied by changes in energy sensing and cell proliferation within the abomasum. Additionally, although fetal restriction down-regulated gene expression of mammalian target of rapamycin and carnitine palmitoyltransferase 1-dependent pathways in the abomasum, RA offspring compensated for this by exhibiting greater activity of AMP-activated kinase-dependent pathways. This study demonstrates a role for perinatal nutrition in the peripheral control of food intake and in energy sensing in the gastric mucosal and emphasizes the importance of diet in early life in regulating energy metabolism during adulthood.