Morphology, adipocyte size, and fatty acid analysis of dairy cattle digital cushions, and the effect of body condition score and age.

The digital cushion is an essential part of maintaining a healthy foot, working to dissipate foot strike and body weight forces and lameness from claw horn disruption lesions. Despite the importance of the digital cushion, little is known about the basic anatomy, adipocyte morphology, and fatty acid composition in relation to age, limb position, and body condition score. In total, 60 claws (from 17 cows) were selected and collected from a herd, ensuring that body condition score data and computed micro-tomography were known for each animal. Digital cushion tissue underwent histological staining combined with stereology, systematic random sampling, and cell morphology analysis, in addition to lipid extraction followed by fatty acid analysis. The results describe digital cushion architecture and adipocyte sizes. Adipocyte size was similar across all 4 claws (distal left lateral and medial and distal right lateral and medial) and across the ages (aged 2-7 yr); however, animals with body condition score of 3.00 or more at slaughter had a significantly increased cell size in comparison to those with a score of less than 2.50. Of 37 fatty acid methyl esters identified, 5 differed between either the body condition score or different age groups. C10:0 capric acid, C14:0 myristic acid, C15:0 pentadecanoic acid, and C20:0 arachidic acid percentages were all lesser in lower body condition score cows, whereas C22:1n-9 erucic acid measurements were lesser in younger cows. Saturated fatty acid, monounsaturated fatty acid, and polyunsaturated fatty acid percentages were not altered in the different claws, ages, or body condition score groups. Triglyceride quantities did not differ for claw position or age but had decreased quantities in lower body condition score animals. Digital cushion anatomy, cellular morphology, and fatty acid composition have been described in general and also in animals with differing ages, body condition scores, and in the differing claws. Understanding fat deposition, mobilization, and composition are essential in not only understanding the roles that the digital cushion plays but also in preventing disorders and maintaining cattle health and welfare.

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.

Influence of birth weight on gene regulators of lipid metabolism and utilization in subcutaneous adipose tissue and skeletal muscle of neonatal pigs.

Epidemiological studies suggest that low-birth weight infants show poor neonatal growth and increased susceptibility to metabolic syndrome, in particular, obesity and diabetes. Adipose tissue development is regulated by many genes, including members of the peroxisome proliferator-activated receptor (PPAR) and the fatty acid-binding protein (FABP) families. The aim of this study was to determine the influence of birth weight on key adipose and skeletal muscle tissue regulating genes. Piglets from 11 litters were ranked according to birth weight and 3 from each litter assigned to small, normal, or large-birth weight groups. Tissue samples were collected on day 7 or 14. Plasma metabolite concentrations and the expression of PPARG2, PPARA, FABP3, and FABP4 genes were determined in subcutaneous adipose tissue and skeletal muscle. Adipocyte number and area were determined histologically. Expression of FABP3 and 4 was significantly reduced in small and large, compared with normal, piglets in adipose tissue on day 7 and in skeletal muscle on day 14. On day 7, PPARA and PPARG2 were significantly reduced in adipose tissue from small and large piglets. Adipose tissue from small piglets contained more adipocytes than normal or large piglets. Birth weight had no effect on adipose tissue and skeletal muscle lipid content. Low-birth weight is associated with tissue-specific and time-dependent effects on lipid-regulating genes as well as morphological changes in adipose tissue. It remains to be seen whether these developmental changes alter an individual's susceptibility to metabolic syndrome.

Developmental regulation of the lung in preparation for life after birth: hormonal and nutritional manipulation of local glucocorticoid action and uncoupling protein-2.

Glucocorticoid action has a major role in regulating fetal and postnatal lung development, although its impact on mitochondrial development is less well understood. Critically, the consequences of any change in glucocorticoid action and mitochondrial function in early life may not be limited to the postnatal period, but may extend into later life. This paper focuses on more recent findings on the impact of ontogeny, fetal cortisol status, maternal nutrient restriction and postnatal leptin administration on mitochondrial uncoupling protein (UCP)-2, glucocorticoid receptor (GR) and 11 beta-hydroxysteroid dehydrogenase type 1 (11betaHSD1) isoform abundance in the lung. For example, in sheep, GR and 11betaHSD1 mRNA are maximal at 140 days' gestation (term approximately 147 days), while UCP2 mRNA peaks at 1 day after birth and then decreases with advancing age. In the fetus, chronic umbilical cord compression enhances the abundance of these genes, an outcome that can also be produced after birth following chronic, but not acute, leptin administration. Irrespective of the timing of maternal nutrient restriction in pregnancy, glucocorticoid sensitivity and UCP2 abundance are both upregulated in the lungs of the resulting offspring. In conclusion, prenatal and postnatal endocrine challenges have distinct effects on mitochondrial development in the lung resulting from changes in glucocorticoid action, which can persist into later life. As a consequence, changes in glucocorticoid sensitivity and mitochondrial protein abundance have the potential to be used to identify those at greatest risk of developing later lung disease.

Prolactin, the prolactin receptor and uncoupling protein abundance and function in adipose tissue during development in young sheep.

A primary role of the prolactin receptor (PRLR) during fetal and postnatal development has been suggested to be the regulation of uncoupling protein (UCP) expression. We, therefore, determined whether: (1) the rate of loss of UCP1 from brown adipose tissue after birth was paralleled by the disappearance of PRLR; and (2) administration of either pituitary extract prolactin (PRL) containing a mixture of posttranslationally modified forms or its pseudophosphorylated form (S179D PRL) improved thermoregulation and UCP1 function over the first week of neonatal life. PRLR abundance was greatest in adipose tissue 6 h after birth before declining up to 30 days of age, a trend mirrored by first a gain and then a loss of UCP1. In contrast, in the liver--which does not possess UCPs--a postnatal decline in PRLR was not observed. Administration of PRL resulted in an acute increase in colonic temperature in conjunction with increased plasma concentrations of non-esterified fatty acids and, as a result, the normal postnatal decline in body temperature was delayed. S179D PRL at lower concentrations resulted in a transient rise in colonic temperature at both 2 and 6 days of age. In conclusion, we have demonstrated a close relationship between the ontogeny of UCP1 and the PRLR. Exogenous PRL administration elicits a thermogenic effect suggesting an important role for the PRLR in regulating UCP1 function.

Tissue-specific effects of leptin administration on the abundance of mitochondrial proteins during neonatal development.

Many tissues undergo a rapid transition after birth, accompanied by dramatic changes in mitochondrial protein function. In particular, uncoupling protein (UCP) abundance increases at birth in the lung and adipose tissue, to then gradually decline, an adaptation that is important in enabling normal tissue function. Leptin potentially mediates some of these changes and is known to promote the loss of UCP1 from brown fat but its effects on UCP2 and related mitochondrial proteins (i.e. voltage-dependent anion channel (VDAC) and cytochrome c) in other tissues are unknown. We therefore determined the effects of once-daily jugular venous administration of ovine recombinant leptin on mitochondrial protein abundance as determined by immunoblotting in tissues that do (i.e. the brain and pancreas) and do not (i.e. liver and skeletal muscle) express UCP2. Eight pairs of 1-day-old lambs received either 100 mug leptin or vehicle daily for 6 days, before tissue sampling on day 7. Administration of leptin diminished UCP2 abundance in the pancreas, but not the brain. Leptin administration had no affect on the abundance of VDAC or cytochrome c in any tissue examined. In leptin-administered animals, but not controls, UCP2 abundance in the pancreas was positively correlated with VDAC and cytochrome c content, and UCP2 abundance in the brain with colonic temperature. In conclusion, leptin administration to neonatal lambs causes a tissue-specific loss of UCP2 from the pancreas. These effects may be important in the regulation of neonatal tissue development and potentially for optimising metabolic control mechanisms in later life.

Endocrine and nutritional regulation of fetal adipose tissue development.

In the fetus, adipose tIssue comprises both brown and white adipocytes for which brown fat is characterised as possessing the unique uncoupling protein (UCP)1. The dual characteristics of fetal fat reflect its critical role at birth in providing lipid that is mobilised rapidly following activation of UCP1 upon cold exposure to the extra-uterine environment. A key stage in the maturation of fetal fat is the gradual rise in the abundance of UCP1. For species with a mature hypothalamic-pituitary axis at birth there is a gradual increase in the amount and activity of UCP1 during late gestation, in conjunction with an increase in the plasma concentrations of catecholamines, thyroid hormones, cortisol, leptin and prolactin. These may act individually, or in combination, to promote UCP1 expression and, following the post-partum surge in each hormone, UCP1 abundance attains maximal amounts. Adipose tIssue grows in the fetus at a much lower rate than in the postnatal period. However, its growth is under marked nutritional constraints and, in contrast to many other fetal organs that are unaffected by nutritional manipulation, fat mass can be significantly altered by changes in maternal and, therefore, fetal nutrition. Fat deposition in the fetus is enhanced during late gestation following a previous period of nutrient restriction up to mid gestation. This is accompanied by increased mRNA abundance for the receptors of IGF-I and IGF-II. In contrast, increasing maternal nutrition in late gestation results in less adipose tIssue deposition but enhanced UCP1 abundance. The pronounced nutritional sensitivity of fetal adipose tIssue to both increased and decreased maternal nutrition may explain why the consequences of an adverse nutritional environment persist into later life.

The effect of maternal prolactin infusion during pregnancy on fetal adipose tissue development.

The present study determines whether maternal administration of prolactin (PRL) to dams promotes the abundance of the brown adipose tissue-specific uncoupling protein-1 (UCP1) in fetal and neonatal rat pups. Recombinant PRL (24 micro g/kg per day), or an equivalent volume of saline, were infused into dams (n=19 per group) throughout pregnancy from 12 h after mating. Interscapular brown adipose tissue was sampled either from fetuses at 19.5 days of gestation (term=21.5 days) or from neonatal rat pups at approximately 18 h after birth. The abundance of UCP1 was determined by immunoblotting on adipose tissue samples from individual pups and pooled from groups of pups. This analysis was complemented by immunocytochemistry on representative adipose tissue samples. Maternal PRL infusion resulted in a greater abundance of UCP1 in fetal rats at 19.5 days of gestation (control: 97.2+/-8.4% reference; PRL: 525.6+/-74.4% reference; P<0.001) and in neonates 18 h after birth. In contrast, the abundance of the outer mitochondrial membrane protein voltage-dependent anion channel was unaffected by PRL. Neonatal adipose tissue sampled from pups born to PRL-infused dams possessed fewer lipid droplets, but more UCP1, as determined by immunocytochemistry. Fetal, but not maternal, plasma leptin concentrations were also increased by maternal PRL administration. In conclusion, as rats are altricial, and the potential thermogenic activity of brown adipose tissue develops over the first few days of postnatal life, these changes prior to, and at the time of, birth implicate PRL in fetal and neonatal adipose tissue maturation.

Influence of genotype on the differential ontogeny of uncoupling protein 2 and 3 in subcutaneous adipose tissue and muscle in neonatal pigs.

The present study aimed to determine whether porcine genotype and/or postnatal age influenced mRNA abundance or protein expression of uncoupling protein (UCP)2 or 3 in subcutaneous adipose tissue (AT) and skeletal muscle (SM) and the extent to which these differences are associated with breed-specific discordance in endocrine and metabolic profiles. Piglets from commercial and Meishan litters were ranked according to birth weight. Tissue samples were obtained from the three median piglets from each litter on either day 0, 4, 7, 14 or 21 of neonatal life. UCP2 protein abundance in AT was similar between genotypes on the first day of life, but it was elevated at all subsequent postnatal ages (P<0.05) in AT of Meishan piglets. In contrast, UCP2 mRNA abundance was lower in Meishans up to 14 days of age. UCP2 mRNA expression was not correlated with protein abundance in either breed at any age. UCP3 mRNA in AT was similar between breeds up to day 7; thereafter, expression was higher (general linear model, P<0.05) in Meishan piglets. Conversely, UCP3 mRNA expression in SM was higher in commercial piglets after day 7. Colonic temperature remained lower in Meishan than commercial piglets throughout the study; this was most obvious in the immediate post-partum period when Meishan piglets had lower (P<0.05) plasma triiodothyronine. In conclusion, we have demonstrated that porcine genotype influences the expression and abundance of UCP2 and 3, an influence which may, in part, be due to the distinctive endocrine profiles associated with each genotype.

Maternal nutrition alters the expression of insulin-like growth factors in fetal sheep liver and skeletal muscle.

We investigated the influence of maternal dietary restriction between days 28 and 80 of gestation followed by re-feeding to the intake of well-fed ewes up to 140 days of gestation (term is 147 days) in sheep, on expression of mRNA for insulin-like growth factor (IGF)-I, IGF-II and growth hormone receptor (GHR) in fetal liver and skeletal muscle. Singleton bearing ewes either consumed 3.2-3.8 MJ/day of metabolisable energy (ME) (i.e. nutrient restricted - approximately 60% of ME requirements, taking into account requirements for both ewe maintenance and growth of the conceptus) or 8.7-9.9 MJ/day (i.e. well fed - approximately 150% of ME requirements) between days 28 and 80 of gestation. All ewes were then well fed (150% of ME requirements) up to day 140 of gestation and consumed 8-10.9 MJ/day. At days 80 and 140 of gestation, five ewes were sampled from each group and fetal tissues taken. There was no difference in fetal body weight or liver weights between groups at either sampling date, or skeletal muscle (quadriceps) weight at 140 days. IGF-I mRNA abundance was lower in livers of nutrient-restricted fetuses at day 80 of gestation (nutrient restricted 2.35; well fed 3.70 arbitrary units), but was higher than well-fed fetuses at day 140 of gestation, after 60 days of re-feeding (restricted/re-fed 4.27; well fed 2.83;s.e.d. 0.98 arbitrary units, P=0.061 for dietxage interaction). IGF-II mRNA abundance was consistently higher in livers of nutrient-restricted fetuses (80 days: nutrient restricted 7.78; well fed 5.91; 140 days: restricted/re-fed 7.23; well fed 6.01;s.e.d. 1.09 arbitrary units, P=0.061 for diet). Nutrient restriction had no effect on hepatic GHR mRNA abundance, but re-feeding of previously nutrient-restricted fetuses increased GHR mRNA compared with continuously well-fed fetuses (80 days: nutrient restricted 70.6; well fed 75.1; 140 days: restricted/re-fed 115.7; well fed 89.4;s.e.d. 10.13 arbitrary units, P=0.047 for dietxage interaction). In fetal skeletal muscle, IGF-I mRNA abundance was not influenced by maternal nutrition and decreased with gestation age (P<0.01). IGF-II mRNA abundance was higher in skeletal muscle of nutrient-restricted fetuses compared with well-fed fetuses at day 80 of gestation (nutrient restricted 16.72; well fed 10.53 arbitrary units), but was lower than well-fed fetuses after 60 days of re-feeding (restricted/re-fed 7.77; well fed 13.72;s.e.d. 1.98 arbitrary units, P<0.001 for dietxage interaction). There was no effect of maternal nutrition or gestation age on fetal skeletal muscle GHR expression. In conclusion, maternal nutrient restriction in early to mid gestation with re-feeding thereafter results in alterations in hepatic and skeletal muscle expression of IGF-I, IGF-II and/or GHR in the fetus which may subsequently relate to altered organ and tissue function.

Influence of cortisol on adipose tissue development in the fetal sheep during late gestation.

The present study examined the extent to which the late gestation rise in fetal plasma cortisol influenced adipose tIssue development in the fetus. The effect of cortisol on the abundance of adipose tIssue mitochondrial proteins on both the inner (i.e. uncoupling protein (UCP)1) and outer (i.e. voltage-dependent anion channel (VDAC)) mitochondrial membrane, together with the long and short forms of the prolactin receptor (PRLR) protein and leptin mRNA was determined. Perirenal adipose tIssue was sampled from ovine fetuses to which (i) cortisol (2-3 mg/day for 5 days) or saline was infused up to 127-130 days of gestation, and (ii) adrenalectomised and intact controls at between 142 and 145 days of gestation (term=148 days). UCP1 protein abundance was significantly lower in adrenalectomised fetuses compared with age-matched controls, and UCP1 was increased by cortisol infusion and with gestational age. Adrenalectomy reduced the concentration of the long form of PRLR, although this effect was only significant for the highest molecular weight isoform. In contrast, neither the short form of PRLR, VDAC protein abundance or leptin mRNA expression was significantly affected by gestational age or cortisol status. Fetal plasma triiodothyronine concentrations were increased by cortisol and with gestational age, an affect abolished by adrenalectomy. When all treatment groups were combined, both plasma cortisol and triiodothyronine concentrations were positively correlated with UCP1 protein abundance. In conclusion, an intact adrenal is necessary for the late gestation rise in UCP1 protein abundance but cortisol does not appear to have a major stimulatory role in promoting leptin expression in fetal adipose tIssue. It remains to be established whether effects on UCP1 protein are directly regulated by cortisol alone or mediated by other anabolic fetal hormones such as triiodothyronine.

Hormonal and nutritional regulation of adipose tissue mitochondrial development and function in the newborn.

Growth, development, and maturation of adipose tissue in the fetus can determine both survival at birth as well as having longer term consequences for adult disease. The mitochondrial proteins uncoupling protein (UCP) 1, voltage dependent anion channel (VDAC), and cytochrome c have an important role in cellular energy regulation. Activity of these proteins is particularly important during the transition from fetal to neonatal life when cellular energy requirements are at near maximal rates. The regulation of these proteins by endocrine factors is highly complex and may be dependent on both fetal number and maternal nutrition. The cytokine hormones leptin and prolactin have well established functions in energy regulation and lactation respectively. However, recent data proposes a role in regulation of mitochondrial proteins, particularly UCP1, and thermogenesis. Cortisol is an adrenal hormone with a critical role in fetal tissue maturation, especially the lung. It has now been shown to influence the abundance of UCP1 in the fetus, a role that may in part be regulated by the metabolically active thyroid hormone triiodothyronine. A greater understanding of the regulation of mitochondrial proteins within adipose tissue by endocrine and nutritional factors is likely to be important in preventing neonatal morbidity and mortality. It could also add substantially to our understanding of pathological conditions such as obesity and non-insulin dependent diabetes.

Maternal nutrient restriction during placental growth, programming of fetal adiposity and juvenile blood pressure control.

Epidemiological and experimental studies have demonstrated that maternal undernutrition during pregnancy is associated with abnormal placental growth. In sheep, maternal nutrient restriction over the period of rapid placental growth (30-80 days) restricts placentome growth. Then following adequate nutrition up to term (147 days), placental mass is greater in association with a higher total abundance of the predominant placental glucose transporter-1. The resulting lambs are larger at birth, have heavier kidneys with an increased expression of the glucocorticoid-responsive type 1 angiotensin II receptor. Near to term, these fetuses possess more adipose tissue, the endocrine sensitivity of which is markedly enhanced. For example, the abundance of mRNA for 11beta-hydroxysteroid dehydrogenase type 1, which catalyses the conversion of cortisone to bio-active cortisol is increased. This is associated with a higher abundance of both leptin and glucocorticoid receptor mRNA. At 6 months of age, the juvenile offspring of nutrient restricted ewes have lower resting blood pressure that was positively correlated with plasma cortisol concentration, suggesting their blood pressure could be more strongly driven by circulating cortisol. These offspring also exhibited a greater pressor response to vasoconstrictor challenges, but showed no difference in vasodilatory response. At this age, the kidney weight was similar between groups, but the abundance of cytochrome c in kidney mitochondria was enhanced in lambs born to nutrient restricted ewes that could indicate increased mitochondrial activity. Reduced maternal nutrition during the period of rapid placental growth may therefore contribute to hypertension in later life through physiological and vascular adaptations during fetal life.

The influence of maternal protein nutrition on offspring development and metabolism: the role of glucocorticoids.

The consequences of sub-optimal nutrition through alterations in the macronutrient content of the maternal diet will not simply be reflected in altered neonatal body composition and increased mortality, but are likely to continue into adulthood and confer greater risk of metabolic disease. One mechanism linking manipulations of the maternal environment to an increased risk of later disease is enhanced fetal exposure to glucocorticoids (GC). Tissue sensitivity to cortisol is regulated, in part, by the GC receptor and 11ß-hydroxysteroid dehydrogenase (11ß-HSD) types 1 and 2. Several studies have shown the effects of maternal undernutrition, particularly low-protein diets, on the programming of GC action in the offspring; however, dietary excess is far more characteristic of the diets consumed by contemporary pregnant women. This study investigated the programming effects of moderate protein supplementation in pigs throughout pregnancy. We have demonstrated an up-regulation of genes involved in GC sensitivity, such as GC receptor and 11ß-HSD, in the liver, but have yet to detect any other significant changes in these piglets, with no differences observed in body weight or composition. This increase in GC sensitivity was similar to the programming effects observed following maternal protein restriction or global undernutrition during pregnancy.

Effect of Acute Administration of Recombinant Human Leptin during the Neonatal Period on Body Temperature and Endocrine Profile of the Piglet.

BACKGROUND: Leptin is produced predominantly by white adipocytes; in adults it regulates appetite and energy expenditure but its role in the neonate remains to be fully established. OBJECTIVES: To examine the effects of acute administration of recombinant human leptin on the endocrine profile and thermoregulation of neonatal pigs. METHODS: 24 pairs of siblings (n = 48) were administered with either a single dose (4 microg ml(-1) kg(-1) body weight) of leptin (L: n = 24) or a placebo (P: n = 24) on day 6 of neonatal life. Rectal temperature was recorded, and tissue samples were taken at 1 (n = 12), 2 (n = 12), 4 (n = 12) or 6 (n = 12) hours post-administration. Plasma concentrations of hormones and metabolites were determined in conjunction with messenger RNA (mRNA) for leptin and uncoupling protein-2. RESULTS: Plasma leptin increased following leptin administration, and differences in concentrations of insulin, thyroxine and non-esterified fatty acids were observed between the two groups. Initially, rectal temperature decreased in L pigs but returned to start values by 1.5 h. This decline in rectal temperature was delayed in placebo animals, resulting in differences between treatments at 1.5 and 2 h. CONCLUSIONS: Acute leptin administration alters the endocrine profile of pigs and influences the thermoregulatory ability of the neonate.

Maternal dexamethasone administration and the maturation of perirenal adipose tissue of the neonatal sheep.

Maternal dexamethasone administration promotes fetal maturation such that thermoregulation is improved following premature delivery and is thus comparable with a full term birth. In the present study we determined the impact of dexamethasone on both the mothers' metabolic status together with adipose tissue function in the newborn. Glucocorticoid action, adipokine gene expression and mitochondrial protein abundance were measured in perirenal adipose tissue of neonatal sheep that were born into either a warm (30 degrees C) or cool (15 degrees C) ambient temperature at 140 days of gestation (dGA; term approximately 147 dGA), either two days after maternal dexamethasone administration, or at 146 dGA for controls. Dexamethasone administration resulted in a reduction in maternal food intake in conjunction with raised plasma cortisol and free triiodothyronine. In offspring of dexamethasone administered mothers, plasma cortisol was lower and non-esterified fatty acids (NEFA) higher than controls. Glucocorticoid receptor (GR), 11beta-hydroxysteroid dehydrogenase (11beta-HSD1), interleukin-6 and uncoupling protein (UCP)1 and 2 mRNA together with voltage dependent anion channel, cytochrome c protein and UCP1 abundance were all increased by dexamethasone administration and being born into a cool ambient temperature. Gene expression of tumor necrosis factor alpha, adiponectin and peroxisome proliferator-activated receptor transcription factor gamma were unaffected by dexamethasone. The abundance of mRNA for the GR, 11beta-HSD1, UCP1 and 2 mRNA together with each protein were positively correlated to plasma NEFA and negatively correlated to plasma cortisol. In conclusion, despite reduced maternal food intake dexamethasone promotes maturation of glucocorticoid action and mitochondrial protein abundance in the newborn, an adaptation dependent on delivery temperature.

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.

Different effects of maternal parity, cold exposure and nutrient restriction in late pregnancy on the abundance of mitochondrial proteins in the kidney, liver and lung of postnatal sheep.

Adaptation to the extrauterine environment at birth relies upon the onset of postnatal function and increased metabolism in the lungs, liver and kidney, mediated partly by activation of mitochondrial proteins such as the voltage-dependent anion channel (VDAC), cytochrome c and, in the lung only, uncoupling protein (UCP)2. The magnitude of adaptation is dependent on the maternal metabolic and endocrine environment. We, therefore, examined the influence of maternal cold exposure (MCE) induced by winter shearing of pregnant sheep in conjunction with nutrient restriction (NR; 50% reduction in maternal food intake from 110 days gestation up to term). The effect of parity was also examined, as the offspring of nulliparous mothers are growth restricted compared with multiparous offspring. All sheep were twin bearing. One twin was sampled after birth and its sibling at 30 days. In the lung, both MCE and maternal nulliparity enhanced UCP2 abundance. However, whilst VDAC abundance was decreased in both the offspring of nulliparous mothers and by NR, it was transiently raised by MCE. Kidney VDAC abundance was reduced by MCE and nulliparity, adaptations only influenced by NR in multiparous mothers. Cytochrome c abundance was raised by MCE and by NR in multiparous controls and raised in offspring of nulliparous mothers. Liver VDAC and cytochrome c abundance were transiently reduced by MCE and persistently lower in offspring of nulliparous mothers. In conclusion, changes in the maternal metabolic environment have marked tissue-specific effects on mitochondrial protein abundance in the lungs, liver and kidney that may be important in enabling the newborn to effectively adapt to the extrauterine environment.

Ontogeny and nutritional programming of uncoupling protein-2 and glucocorticoid receptor mRNA in the ovine lung.

This study investigated the developmental and nutritional programming of uncoupling protein-2 (UCP2), glucocorticoid receptor (GR) and 11beta-hydroxysteroid dehydrogenase type 1 (11betaHSD1) mRNA in the sheep lung from the time of uterine attachment to 6 months of age. The effect of maternal nutrient restriction on lung development was determined in early to mid gestation (i.e. 28-80 days gestation, period of maximal placental growth, and embryonic and pseudoglandular stages of fetal lung development) and late gestation (i.e. 110-147 days gestation, period of maximal fetal growth, and canalicular and saccular stages of fetal lung development). Fetal lungs were sampled at 80 and 140 days (term approximately 148 days) gestation, and sheep lungs at 1, 7, 30 days and 6 months. GR and 11betaHSD1 mRNA were maximal at 140 days gestation, whereas UCP2 mRNA peaked at 1 day of age and then declined with postnatal age. Maternal nutrient restriction in both early-to-mid and late gestation had no effect on lung weight, but increased UCP2, GR and 11betaHSD1 mRNA abundance at every sampling age. These findings suggest that the developmental ontogeny of UCP2 mRNA in the ovine lung is under local glucocorticoid hormone action and that maternal nutrient restriction has long-term consequences for UCP2 and GR mRNA abundance in the lung irrespective of its timing.

Increased uncoupling protein-2 mRNA abundance and glucocorticoid action in adipose tissue in the sheep fetus during late gestation is dependent on plasma cortisol and triiodothyronine.

The endocrine regulation of uncoupling protein-2 (UCP2), an inner mitochondrial protein, in fetal adipose tissue remains unclear. The present study aimed to determine if fetal plasma cortisol and triiodothyronine (T3) influenced the mRNA abundance of UCP2, glucocorticoid receptor (GR) and 11beta-hydroxysteroid dehydrogenase type 1 (11betaHSD1) and 2 (11betaHSD2) in fetal adipose tissue in the sheep during late gestation. Perirenal-abdominal adipose tissue was sampled from ovine fetuses to which either cortisol (2-3 mg kg(-1) day(-1)) or saline was infused for 5 days up to 127-130 days gestation, or near term fetuses (i.e. 142-145 days gestation) that were either adrenalectomised (AX) or remained intact. Fetal plasma cortisol and T3 concentrations were higher in the cortisol infused animals and lower in AX fetuses compared with their corresponding control group, and increased with gestational age. UCP2 and GR mRNA abundance were significantly lower in AX fetuses compared with age-matched controls, and increased with gestational age and by cortisol infusion. Glucocorticoid action in fetal adipose tissue was augmented by AX and suppressed by cortisol infusion, the latter also preventing the gestational increase in 11betaHSD1 mRNA and decrease in 11betaHSD2 mRNA. When all treatment groups were combined, both fetal plasma cortisol and T3 concentrations were positively correlated with UCP2, GR and 11betaHSD2 mRNA abundance, but negatively correlated with 11betaHSD1 mRNA abundance. In conclusion, plasma cortisol and T3 are both required for the late gestation rise in UCP2 mRNA and differentially regulate glucocorticoid action in fetal adipose tissue in the sheep during late gestation.