Prenatal Protein Restriction Research Articles

Maternal low protein diet leads to placental angiogenic compensation via dysregulated M1/M2 macrophages and TNFα expression in Sprague-Dawley rats

A maternal low-protein (LP) diet in Sprague-Dawley rats results in low birth weight, rapid adipose tissue catch-up growth, adult obesity, and insulin resistance. The placenta functions to fulfill the fetus’ nutrient demands. Adequate angiogenic factor concentrations help to ensure normal growth and vasculature development of the placenta and, in turn, optimum maternal-to-fetal nutrient delivery. Maternal malnutrition creates a proinflammatory environment that leads to inhibition of placental tissue growth. Therefore, we hypothesized that a maternal LP diet will lead to abnormal angiogenesis via dysregulation of immune cells resulting in increased secretion of proinflammatory cytokines and reduced angiogenic factor expression. Sprague-Dawley dams were fed 8% LP or 20% normal protein diets for 3 weeks prior to breeding and throughout pregnancy. Placenta from dams fed a LP diet weighed less; had increased M2 macrophages producing TNFα, decreased M1 macrophages and iNKT cells; greater angiogenic factor (FGF2, VEGFR-1, IGF2) expression and protein content, and greater CD31/PECAM (platelet endothelial cell adhesion molecule) expression. Prenatal protein restriction may induce the placenta to upregulate compensatory mechanisms of angiogenesis in order to meet the nutrient demands of the fetus.

Maternal low protein diet leads to placental angiogenic compensation via dysregulated M1/M2 macrophages and TNFα expression in Sprague‐Dawley rats

A maternal low‐protein (LP) diet results in low birth weight, increased offspring rapid adipose tissue catch‐up growth, adult obesity, and insulin resistance in Sprague‐Dawley rats. The placenta plays key roles in nutrient transport and fetal growth. Placental function is dependent on regulation of immune cell populations and growth and angiogenic factors. Therefore, we hypothesize that a maternal LP diet leads to placental dysfunction through dysregulation of immune cell populations, cytokine production, and growth/angiogenic factors. Obese‐prone Sprague‐Dawley dams were fed 8% LP or20% normal protein diets for 3 weeks prior to breeding and through pregnancy. Maternal LP diet led to a decrease in placental weight and efficiency. LP diet placent as had an increase in angiogenic factors, FGF2, VEGFR‐1, IGF2, M2macrophages producing TNFα and a decrease in M1 macrophages and iNKT cells. These results suggest that prenatal protein restriction forces the placenta to upregulate compensating mechanisms of angiogenesis in order to fulfill the nutrient demands of the fetus.Support or Funding InformationThis work was supported by USDA Agricultural Research Service Project #3062‐51000‐052‐00D.

Maternal Low Protein Diet Reduces Birth Weight And Increases Brown Adipose Tissue UCP‐1 and FNDC5 Gene Expression in Male Neonatal Sprague‐Dawley Rats

Brown adipose tissue (BAT) plays an important role in regulating body weight (BW) by modifying thermogenesis. Maternal low protein (LP) diets reduce offspring birth weight. Increased BAT thermogenesis in utero may be one mechanism for the lower BW. However, whether maternal LP nutrition alters BAT thermogenesis and BW of offspring in-utero is not yet known. We fed obese-prone Sprague-Dawley dams 8% low protein (LP) or 20% normal protein (NP) diets for 3 weeks prior to breeding and through pregnancy. BW and gene expression of interscapular BAT (iBAT) thermogenic markers were measured in male fetal (gestation day 18) and neonatal (day 0 or 1) offspring. BW of neonatal LP males was lower than NP males but no difference was observed in females. Gene expression of thermogenic factors UCP-1 and UCP-3 and transcription factors PRDM16 and PPARa in iBAT were 2- to 6-fold greater in LP than NP male neonatal offspring. FNDC5, a precursor of irisin and activator of thermogenesis, was expressed 2-fold greater in neonatal LP iBAT than NP males. However, fetal iBAT UCP-1, PRDM16, PPARa and irisin mRNA did not differ between LP and NP groups. Maternal LP diet had no effects on placental irisin and UCP-2 expression. These results suggest that prenatal protein restriction increases the risk for low BW through mechanisms affecting full-term offspring iBAT thermogenesis but not greatly altering fetal iBAT or placental thermogenesis. This work was supported by USDA Agricultural Research Service Project #3062-51000-052-00D.

Maternal low protein diet leads to dysregulation of placental iNKT cells and M1/M2 macrophage ratio, body weight loss in male, neonate Sprague‐Dawley rats and increased UCP‐1 mediated thermogenesis

Placental immune cells provide cytokines and growth factors that are necessary for placenta development and function. Invariant natural killer T (iNKT) cells are innate cells specific for glycolipid antigens presented by the CD1d molecule and secrete Th1 cytokines in the placenta, suggesting an immunoregulatory role. Self‐lipid antigens at the maternal‐fetal interface may activate iNKT cells, leading to placental inflammation and dysfunction, which can increase brown adipose tissue (BAT) thermogenesis and reduce fetal growth. Maternal low protein (LP) diets reduce offspring birth weight (BW) perhaps via a BAT thermogenesis‐mediated effect. However, whether maternal LP nutrition alters placental immune cell populations and offspring thermogenesis in not yet known. Obese‐prone Sprague‐Dawley dams were fed 8% LP or 20% normal protein (NP) diets for 3 wks prior to breeding and through pregnancy. BW of neonatal LP males was lower than NP males. Vα14 mRNA marker for iNKT cells was 11‐fold higher in LP placenta, while there was also an increase in proinflammatory M1/M2 macrophage mRNA marker ratio. UCP‐1 gene and protein expression and transcription factors PRDM16 and PPARα in BAT were 2‐ to 6‐fold greater in LP than NP neonatal males. FNDC5, an irisin precursor and thermogenesis activator, was 2‐fold greater in neonatal LP BAT than NP males. These results suggest that prenatal protein restriction increases proinflammatory iNKT and M1 macrophages in the placenta, leading to placental dysfunction, increased offspring BAT thermogenesis, and low BW.

Maternal low-protein diet causes body weight loss in male, neonate Sprague–Dawley rats involving UCP-1-mediated thermogenesis

Brown adipose tissue (BAT) plays an important role in regulating body weight (BW) by modifying thermogenesis. Maternal low protein (LP) diets reduce offspring birth weight. Increased BAT thermogenesis in utero may be one mechanism for the lower BW. However, whether maternal LP nutrition alters BAT thermogenesis and BW of offspring in utero is not yet known. We fed obese-prone Sprague–Dawley dams 8% LP or 20% normal protein (NP) diets for 3weeks prior to breeding and through pregnancy. BW and gene expression of interscapular BAT (iBAT) thermogenic markers were measured in male fetal (gestation day 18) and neonatal (day 0 or 1) offspring. BW of neonatal LP males was lower than NP males but no difference was observed in females. Gene and protein expression of UCP-1 and transcription factors PRDM16 and PPARα in iBAT were 2- to 6-fold greater in LP than in NP male neonatal offspring. FNDC5, a precursor of irisin and activator of thermogenesis, was expressed 2-fold greater in neonatal LP iBAT than NP males. However, fetal iBAT UCP-1, PRDM16, PPARα and irisin mRNA did not differ between LP and NP groups. Maternal LP diet had no effects on placental irisin and UCP-2 expression. These results suggest that prenatal protein restriction increases the risk for low BW through mechanisms affecting full-term offspring iBAT thermogenesis but not greatly altering fetal iBAT or placental thermogenesis.

Is the Fetal Origins Hypothesis of Diabetes Supported by Animal Research? A Systematic Review and Meta-Analysis of the Evidence

The fetal programming hypothesis states that fetal undernutrition during pregnancy results in permanent changes in the offspring’s metabolism. A large number of animal studies have evaluated the effect of prenatal undernutrition on later glucose metabolism. Aim: We systematically reviewed the existing animal literature examining effects of prenatal undernutrition on glucose and insulin metabolism. Methods: An electronic search was performed in Medline and Embase to identify all articles that reported studies investigating the effect of prenatal undernutrition on plasma insulin, plasma glucose and beta cell mass in animal models. Summary estimates of the effect of prenatal undernutrition on mean glucose concentration, insulin level, and beta cell mass were obtained through meta-analysis. Results: The search resulted in 1827 articles, of which 117 were potentially eligible, based on title and abstract, and 49 met the selection criteria and were included in the review. Prenatal protein restriction (but not general undernutrition) increased plasma glucose concentrations (0.42 mmol/l (95% CI 0.07 to 0.77)). Both prenatal general undernutrition and protein restriction reduced plasma insulin concentrations (general undernutrition: -0.03 nmol/l (95% CI -0.04 to -0.01), protein restricted: -0.04 nmol/l (95% CI -0.08 to 0.00)) and beta cell mass (general undernutrition: -1.24 mg (95% CI -1.88 to -0.60), protein restriction: -0.99 mg (95% CI -1.67 to -0.31)). In all cases, heterogeneity was significant. Conclusions: Despite significant heterogeneity, evidence from experiments in different species suggests that prenatal undernutrition – both general or protein restriction – results in increased glucose and reduced insulin concentrations as well as beta cell mass in later life.

Temporal alterations in vascular angiotensin receptors and vasomotor responses in offspring of protein-restricted rat dams

Examine temporal alterations in vascular angiotensin II receptors (AT(1)R and AT(2)R) and determine vascular response to angiotensin II in growth-restricted offspring. Offspring of pregnant rats fed low-protein (6%) and control (20%) diet were compared. Prenatal protein restriction reprogrammed AT(1a)R messenger RNA expression in male rats' mesenteric arteries to cause 1.7- and 2.3-fold increases at 3 and 6 months of age associated with arterial pressure increases of 10 and 33 mm Hg, respectively; however, in female rats, increased AT(1a)R expression (2-fold) and arterial pressure (15 mm Hg) occurred only at 6 months. Prenatal protein restriction did not affect AT(2)R expression. Losartan abolished hypertension, suggesting that AT(1a)R plays a primary role in arterial pressure elevation. Vasoconstriction to angiotensin II was exaggerated in all protein-restricted offspring, with greater potency and efficacy in male rats. Prenatal protein restriction increased vascular AT(1)R expression and vasoconstriction to angiotensin II, possibly contributing to programmed hypertension.

The Effects of Prenatal Protein Restriction onβ-Adrenergic Signalling of the Adult Rat Heart during Ischaemia Reperfusion

A maternal low-protein diet (MLP) fed during pregnancy leads to hypertension in adult rat offspring. Hypertension is a major risk factor for ischaemic heart disease. This study examined the capacity of hearts from MLP-exposed offspring to recover from myocardial ischaemia-reperfusion (IR) and related this to cardiac expression of β-adrenergic receptors (β-AR) and their associated G proteins. Pregnant rats were fed control (CON) or MLP diets (n = 12 each group) throughout pregnancy. When aged 6 months, hearts from offspring underwent Langendorff cannulation to assess contractile function during baseline perfusion, 30 min ischemia and 60 min reperfusion. CON male hearts demonstrated impaired recovery in left ventricular pressure (LVP) and dP/dt max (P < 0.01) during reperfusion when compared to MLP male hearts. Maternal diet had no effect on female hearts to recover from IR. MLP males exhibited greater membrane expression of β 2-AR following reperfusion and urinary excretion of noradrenaline and dopamine was lower in MLP and CON female rats versus CON males. In conclusion, the improved cardiac recovery in MLP male offspring following IR was attributed to greater membrane expression of β 2-AR and reduced noradrenaline and dopamine levels. In contrast, females exhibiting both decreased membrane expression of β 2-AR and catecholamine levels were protected from IR injury.

Developmental Origins of Health and Disease

Risk of chronic disease during adulthood is partly determined by early life experience. Insults, both nutritional and nonnutritional, to the mother during pregnancy appear to programme physiological and metabolic function in the developing offspring, bringing about lasting changes to health. A robust body of epidemiological evidence shows that fetal exposure to maternal undernutrition, or maternal obesity, is associated with greater risk of coronary heart disease, type 2 diabetes, chronic renal disease, and a range of other conditions associated with ageing. The biological plausibility of this nutritional programming has been demonstrated by experiments in which the diet is manipulated during pregnancy in a wide range of animal species. The key focus for research in this area is to determine the mechanisms which lead from maternal insult to offspring disease phenotypes. In this special issue, R. J. Karp and colleagues report findings of a study of children aged 4–6 years, which demonstrated an association between body mass index in childhood and weight gain between the ages of 4 and 6 months. This work emphasises the importance of the relationship between early life influences, later adiposity, and the poor health associated with greater body fatness. This work is complemented by the animal study of J. Beltrand et al., which reports differences in weight gain and body fat in offspring of rats fed a high-fat diet compared to a control group. The mechanistic role of an exaggerated neonatal leptin surge in high-fat-exposed offspring is demonstrated by the ablation of postnatal weight gain following treatment with a leptin antagonist. Insults other than nutrition may also exert programming effects on the developing fetus. G. J. Kummet et al. considered the effects of exposing mouse fetuses to selective serotonin reuptake inhibitors. These drugs are widely prescribed to women of childbearing age and may complicate up to 10% of pregnancies. In mice, fetal exposure was found to generate a hypermetabolic state, associated with greater food intake, but lower body weight. The mechanistic basis of early life programming is widely held to involve influences of nutrition or other maternal signals upon the epigenome. The epigenetic theory was explored by E. K. Zinkhan et al., who demonstrated that placental insufficiency in animals, a manipulation known to programme metabolic disturbance, was associated with alterations to methylation of histones associated with the IGF-1 gene. This link between the placenta and programming, either at the level of the epigenome, or by other mechanisms, may be explained by involvement in the endocrine crosstalk between mother and fetus. As reviewed by E. Aszatalos, transfer of glucocorticoids across the placenta may be a potent programming stimulus, regardless of nutritional status. S. Entringer et al. review the role of placentally derived estrogen in the setting of fetal adrenal cortical function, a physiological process which may have important consequences for homeostatic processes in adult life. The studies of K. J. P. Ryan et al. and S. Engeham et al. consider mechanistic issues that are further downstream from the initial programming insult and more closely associated with the observed disease phenotype. Both studies report findings from an established model of programming resulting from maternal protein restriction in the rat. In the context of renal programming, S. Engeham and colleagues report data which indicates a contribution of programmed mitochondrial function to later function. Protein restriction in utero lowers respiratory rate in mitochondria from adult kidneys. K. J. P. Ryan et al. examined the cardiac response to ischemia-reperfusion injury and noted that programming of β-adrenergic receptor expression may underpin some of the observed effects of prenatal protein restriction. Simon C. Langley-Evans Barbara Alexander Harry J. McArdle Deborah M. Sloboda

Role of the renin–angiotensin–aldosterone system in the enhancement of salt sensitivity caused by prenatal protein restriction in stroke-prone spontaneously hypertensive rats

We previously demonstrated that maternal protein restriction during pregnancy enhanced salt sensitivity and shortened life span in stroke-prone spontaneously hypertensive rats (SHRSP). The present study was conducted to investigate the participation of the renin–angiotensin–aldosterone system in the development of salt sensitivity in the offspring of dams fed a low-protein diet during pregnancy. We used SHRSP offspring from dams fed a 20% casein diet (CN) or a 9% casein diet (LP) during pregnancy. The CN and LP SHRSP offspring were further subdivided into tap-water-drinking and 1%-saline-drinking groups from the postnatal 10th week. A remarkable elevation in blood pressure in response to salt loading was observed in the LP SHRSP offspring. The protein levels of CYP11B2, an enzyme for aldosterone synthesis, were markedly elevated in response to salt loading in the kidneys of LP offspring. Treatment of the LP offspring with an aldosterone receptor antagonist prevented the blood pressure from elevating and lengthened the average life span in LP offspring in response to the drinking of 1% saline. No difference in the activity of angiotensin-converting enzyme or in the protein level of the angiotensin type 1 receptor was found between the CN and LP offspring in either the tap-water-drinking or saline-drinking conditions. In conclusion, the increment of aldosterone production in response to high-salt loading may contribute to the elevated salt sensitivity of the offspring of protein-restricted dams.

Folic Acid and Protein Content in Maternal Diet and Postnatal High-Fat Feeding Affect the Tissue Levels of Iron, Zinc, and Copper in the Rat

Although maternal, fetal, and placental mechanisms compensate for disturbances in the fetal environment, any nutritional inadequacies present during pregnancy may affect fetal metabolism, and their consequences may appear in later life. The aim of the present study is to investigate the influence of maternal diet during gestation on Fe, Zn, and Cu levels in the livers and kidneys of adult rats. The study was carried out on the offspring (n = 48) of mothers fed either a protein-balanced or a protein-restricted diet (18% vs. 9% casein) during pregnancy, with or without folic acid supplementation (0.005- vs. 0.002-g folic acid/kg diet). At 10 weeks of age, the offspring of each maternal group were randomly assigned to groups fed either the AIN-93G diet or a high-fat diet for 6 weeks, until the end of the experiment. The levels of Fe, Zn, and Cu in the livers and kidneys were determined by the F-AAS method. It was found that postnatal exposure to the high-fat diet was associated with increased hepatic Fe levels (p < 0.001), and with decreased liver Zn and Cu contents (p < 0.01 and p < 0.05, respectively), as well as with decreased renal Cu contents (p < 0.001). Moreover, the offspring’s tissue mineral levels were also affected by protein and folic acid content in the maternal diet. Both prenatal protein restriction and folic acid supplementation increased the liver Zn content (p < 0.05) and the kidney Zn content (p < 0.001; p < 0.05, respectively), while folic acid supplementation resulted in a reduction in renal Cu level (p < 0.05). Summarizing, the results of this study show that maternal dietary folic acid and protein intake during pregnancy, as well as the type of postweaning diet, affect Fe, Zn, and Cu levels in the offspring of the rat. However, the mechanisms responsible for this phenomenon are unclear, and warrant further investigation.

Prenatal protein restriction leads to a disparity between aortic and peripheral blood pressure in Wistar male offspring

A host of animal studies have been used to model the effects of exposure to a low protein diet in utero on adult blood pressure. Collection of systolic blood pressure data by the indirect tail-cuff plethysmography method consistently shows increased pressures in low protein exposed rodent offspring compared to controls, but this technique has been criticised as the associated stress artefacts may confound the observed effects. Conversely, radiotelemetry systems allow unrestrained and continuous monitoring of blood pressure through the awake and sleep phases of the diurnal cycle. In this novel study, we directly compared blood pressure parameters in male offspring from low protein and control-fed dams measured simultaneously using tail-cuff and radiotelemetry systems. Control rats showed a good correlation between tail-cuff and radiotelemetry derived blood pressure data. Conversely, low protein males were relatively hypertensive at 8 weeks of age when measured by tail-cuff, but had significantly lower blood pressure than controls at 12 weeks of age when measured by telemetry. Heart rate and length of systole did not differ between the two groups. Individual stress protocols mimicking those imposed by tail-cuff plethysmography (novel environment, heat, restraint, inflation), caused similar increases in blood pressure and heart rate in control and low protein animals, ruling out an effect of enhanced pressor response to stress following prenatal protein restriction. Instead, an increase in peripheral vascular resistance in these animals is considered possible. Such a disparity between central and peripheral blood pressure measurements could have important clinical implications regarding cardiovascular risk assessment and treatment.

The liver X-receptor gene promoter is hypermethylated in a mouse model of prenatal protein restriction

Prenatal nutrition as influenced by the nutritional status of the mother has been identified as a determinant of adult disease. Feeding low-protein diets during pregnancy in rodents is a well-established model to induce programming events in offspring. We hypothesized that protein restriction would influence fetal lipid metabolism by inducing epigenetic adaptations. Pregnant C57BL/6J mice were exposed to a protein-restriction protocol (9% vs. 18% casein). Shortly before birth, dams and fetuses were killed. To identify putative epigenetic changes, CG-dinucleotide-rich region in the promoter of a gene (CpG island) methylation microarrays were performed on DNA isolated from fetal livers. Two hundred four gene promoter regions were differentially methylated upon protein restriction. The liver X-receptor (Lxr) alpha promoter was hypermethylated in protein-restricted pups. Lxr alpha is a nuclear receptor critically involved in control of cholesterol and fatty acid metabolism. The mRNA level of Lxra was reduced by 32% in fetal liver upon maternal protein restriction, whereas expression of the Lxr target genes Abcg5/Abcg8 was reduced by 56% and 51%, respectively, measured by real-time quantitative PCR. The same effect, although less pronounced, was observed in the fetal intestine. In vitro methylation of a mouse Lxra-promoter/luciferase expression cassette resulted in a 24-fold transcriptional repression. Our study demonstrates that, in mice, protein restriction during pregnancy interferes with DNA methylation in fetal liver. Lxra is a target of differential methylation, and Lxra transcription is dependent on DNA methylation. It is tempting to speculate that perinatal nutrition may influence adult lipid metabolism by DNA methylation, which may contribute to the epidemiological relation between perinatal/neonatal nutrition and adult disease.

Epigenetic changes in gene expression: focus on “The liver X-receptor gene promoter is hypermethylated in a mouse model of prenatal protein restriction”

the term epigenetics was first coined in 1942 by Waddington ([20][1]) to describe the interaction of genes with their environment during development that gives rise to a phenotype. Today, the term epigenetics is used when describing a phenotype that occurs in a manner outside conventional genetic

The Liver X‐Receptor (LXR) gene promoter is hypermethylated in a mouse model of prenatal protein restriction

Prenatal nutrition, e.g., nutritional status of the mother, has been epidemiologically identified as a determinant of adult disease. Feeding low‐protein diets during pregnancy in rodents is a well‐established model to induce "programming" events in offspring. We hypothesized that protein restriction would induce epigenetic adaptations which would interfere with lipid metabolism. C57BL/6 mice were fed a protein restricted diet during pregnancy. At day 19.5 of pregnancy, dams and fetuses were sacrificed. CpG island methylation microarrays were performed on fetal liver DNA. 204 promoter regions were differentially methylated upon protein restriction. The liver X‐receptor (Lxr) alpha promoter was hypermethylated in protein‐restricted pups. Lxr alpha is a nuclear receptor critically involved in control of lipid metabolism. mRNA level of Lxra tended to be reduced in fetal liver upon maternal protein restriction, whereas expression of Lxr target genes were significantly reduced. In vitro methylation of a mouse Lxra‐promoter/luciferase expression cassette resulted in a 24‐fold transcriptional repression. Our study demonstrates that, in mice, protein restriction during pregnancy interferes with DNA methylation in fetal liver. Lxra is a target of differential methylation and Lxra transcription is dependent on DNA methylation. We suggest that prenatal nutrition may influence adult lipid metabolism by DNA methylation which may contribute to the epidemiological relation between prenatal/neonatal nutrition and adult disease.Supported by the Dutch Heart Foundation (2004T048).

Postnatal Catch‐up Growth After Fetal Protein Restriction Programs Proliferation of Rat Preadipocytes

We studied the in vitro proliferation and differentiation of rat preadipocytes to investigate whether catch-up growth after prenatal protein restriction may program adipose precursor cells leading to development of increased adipose tissue mass. Pregnant rat dams were fed either an isocaloric low-protein diet (LP-8%) or control diet (C-20%). During lactation, in order to induce catch-up growth, dams from LP group were fed with the C diet and litter size was reduced to four pups instead of eight. Preadipocytes were isolated from weanling male pups (28 days of age). Differentiation and proliferation were assessed across time. At late stages of preadipocyte differentiation, no difference was observed in lipid accumulation of C or LP cultures but the mRNA expression of leptin was enhanced in LP cells. At early stages of culture, a higher DNA and protein content accompanied by a higher rate of proliferation was measured in adipocytes from LP cultures. Moreover, the mRNA expression of cyclin D1 was increased in these cells whereas the expression of peroxisome proliferators-activated receptor gamma (PPARgamma) and steroyl regulatory element binding protein (SREBP-1c) was significantly reduced during early stages. The results suggest that prenatal exposure to a LP followed by rapid catch-up growth is associated with a higher rate for proliferation in preadipocytes.

Sex differences in sensitivity to β-adrenergic agonist isoproterenol in the isolated adult rat heart following prenatal protein restriction

Hypertension is a major risk factor for the development of CVD. Epidemiological studies have shown that low birth weight increases the risk of developing hypertension in adulthood. Hypertension increases the risk of suffering IHD and early findings provide evidence that hearts from prenatally protein-restricted, hypertensive, male offspring are more susceptible to cardiac dysfunction following ischaemic events. Hypertension and abnormalities in cardiac function following ischaemia-reperfusion in the human population are treated therapeutically with beta-adrenergic antagonists. We hypothesised that increased susceptibility to myocardial ischaemia-reperfusion injury in prenatally programmed offspring may be due to sympathetic hyperactivity. Pregnant Wistar rats were fed control or low-protein (maternal low protein; MLP) diets throughout gestation. At age 6 months, hearts were rapidly excised and retro-perfused using the Langendorff apparatus, to assess isolated cardiac function following stimulation with increasing doses of the non-specific beta-agonist isoproterenol. Baseline heart rates were similar in control and MLP-fed offspring. With significant diet x sex interactions (P < 0.01) maximum heart rate response following isoproterenol infusion was significantly longer in MLP than control. Prenatal diet had no effect on maximal left ventricular developed pressure (LVDP) response, but the LVDP isoproterenol response was significantly longer in duration in MLP-exposed male offspring (diet x sex P < 0.001). Myocardial mRNA expression of beta2-adrenergic receptors was increased in 2-week-old female MLP offspring only (P < 0.049). In conclusion, maternal protein restriction programmes cardiac sympathetic activity in a sex-specific manner, and may explain increased susceptibility to ischaemia-reperfusion injury in males subject to fetal undernutrition.

Role of maternal glucocorticoid inducible kinase SGK1 in fetal programming of blood pressure in response to prenatal diet

Maternal stress and malnutrition modify intrauterine fetal development with impact on postnatal blood pressure, nutrient, water, and electrolyte metabolism. The present study explored the possible involvement of maternal serum- and glucocorticoid-inducible kinase (SGK)-1 in fetal programming of blood pressure. To this end, wild-type (sgk1(+/+)) male mice were mated with SGK1 knockout (sgk1(-/-)) female mice, and sgk1(-/-) males with sgk1(+/+) females, resulting in both cases in heterozygotic (sgk1(-/+)) offspring. Following prenatal protein restriction, the offspring of sgk1(+/+) mothers gained weight significantly slower and had significantly higher blood pressure after birth. Moreover, a sexual dimorphism was apparent in fasting blood glucose and plasma corticosterone concentrations, with higher levels in female offspring. In contrast, prenatal protein restriction of sgk1(-/-) mothers had no significant effect on postnatal weight gain, blood pressure, plasma glucose concentration, or corticosterone levels, irrespective of offspring sex. Plasma aldosterone concentration, urinary flow rates, and urinary excretions of Na(+) and K(+) were not significantly modified by either maternal genotype or nutritional manipulation. In conclusion, maternal signals mediated by SGK1 may play a decisive role in fetal programming of hypertension induced by prenatal protein restriction.

Prenatal diet determines susceptibility to cardiac ischaemia–reperfusion injury following treatment with diethylmaleic acid and N-acetylcysteine

Fetal undernutrition programmes increased risk of developing cardiovascular disease in adult life. We hypothesized that prenatal protein restriction would impair recovery in post-ischaemic cardiac function in adult offspring through antioxidant-mediated processes. Pregnant Wistar rats were fed control or maternal low protein diets (MLP) throughout gestation. The offspring of these rats were treated with either saline, N-acetylcysteine (NAC), diethylmaleate (DEM), or both NAC and DEM to manipulate glutathione status at 6 months of age. Hearts were rapidly excised and retro-perfused (Langendorff) to assess isolated cardiac function before (baseline), and during 30 min global ischaemia and 60 min reperfusion. Hearts from adult rats exposed to a MLP diet in utero suffered greater cardiac dysfunction than those from controls following 30 min ischaemia. Left ventricular developed pressure (LVDP) was significantly reduced upon early reperfusion ( p < 0.042) in MLP rats compared to controls. NAC pre-treatment had no effect on LVDP of hearts from control animal hearts but improved the revival of MLP hearts to the same level as controls. DEM treatment did not affect control hearts but significantly reduced recovery of LVDP of MLP hearts during early ( p < 0.008) and late reperfusion (0.035). Combined NAC and DEM treatment had no effect on LVDP between control and MLP fed offspring. Prenatal protein restriction throughout pregnancy increases the susceptibility of the adult rat heart to suffer a functional deficit following ischaemia–reperfusion injury. Pharmacologically improving antioxidant status prevented this injury. A nutritionally-imbalanced developmental environment may increase susceptibility to coronary heart disease through the programming of myocardial glutathione metabolism.

P2-30 Prenatal protein restriction does not alter insulin-stimulated lipogenesis in isolated epididymal fat cells from the rat

P2-30 Prenatal protein restriction does not alter insulin-stimulated lipogenesis in isolated epididymal fat cells from the rat