Intra-uterine growth restriction and the programming of left ventricular remodelling in female rats

Impact of overweight and obesity in the fetal cardiac function parameters in the second and third trimesters of pregnancy

OBJECTIVE

To assess the impact of overweight and obesity in the second and third trimesters of pregnancy on fetal cardiac function parameters.

METHODS

We performed a prospective cohort study of 374 singleton pregnant women between 20w0d and 36w6d divided into three groups: 154 controls (body mass index - BMI < 25 kg/m2), 140 overweight (BMI 25-30 kg/m2) and 80 obese (BMI ≥ 30 kg/m2). Fetal left ventricular (LV) modified myocardial performance index (Mod-MPI) was calculated according to the following formula: (isovolumetric contraction time + isovolumetric relaxation time)/ejection time. Spectral tissue Doppler was used to determine LV and right ventricular (RV) myocardial performance index (MPI'), peak myocardial velocity during systole (S'), early diastole (E'), and late diastole (A').

RESULTS

We found significant differences between the groups in maternal age (p < 0.001), maternal weight (p < 0.001), BMI (p < 0.001), number of pregnancies (p < 0.001), parity (p < 0.001), gestational age (p = 0.013), and estimated fetal weight (p = 0.003). Overweight pregnant women had higher LV Mod-MPI (0.046 versus 0.044 seconds, p = 0.009) and LV MPI' (0.50 versus 0.47 seconds, p < 0.001) than the control group. Obese pregnant women had higher RV E' than control (6.82 versus 6.33 cm/sec, p = 0.008) and overweight (6.82 versus 6.46 cm/sec, p = 0.047) groups. There were no differences in 5-min APGAR score < 7, neonatal intensive care unit admission, hypoglycemia and hyperglobulinemia between the groups.

CONCLUSIONS

We observed fetal myocardial dysfunction in overweight and obese pregnant women with higher LV Mod-MPI, LV MPI' and RV E' compared to fetuses from normal weight pregnant women.

Fetal Cardiac Lipid Sensing Triggers an Early and Sex-related Metabolic Energy Switch in Intrauterine Growth Restriction

CONTEXT

Intrauterine growth restriction (IUGR) is an immediate outcome of an adverse womb environment, exposing newborns to developing cardiometabolic disorders later in life.

OBJECTIVE

This study investigates the cardiac metabolic consequences and underlying mechanism of energy expenditure in developing fetuses under conditions of IUGR.

METHODS

Using an animal model of IUGR characterized by uteroplacental vascular insufficiency, mitochondrial function, gene profiling, lipidomic analysis, and transcriptional assay were determined in fetal cardiac tissue and cardiomyocytes.

RESULTS

IUGR fetuses exhibited an upregulation of key genes associated with fatty acid breakdown and β-oxidation (Acadvl, Acadl, Acaa2), and mitochondrial carnitine shuttle (Cpt1a, Cpt2), instigating a metabolic gene reprogramming in the heart. Induction of Ech1, Acox1, Acox3, Acsl1, and Pex11a indicated a coordinated interplay with peroxisomal β-oxidation and biogenesis mainly observed in females, suggesting sexual dimorphism in peroxisomal activation. Concurring with the sex-related changes, mitochondrial respiration rates were stronger in IUGR female fetal cardiomyocytes, accounting for enhanced adenosine 5'-triphosphate production. Mitochondrial biogenesis was induced in fetal hearts with elevated expression of Ppargc1a transcript specifically in IUGR females. Lipidomic analysis identified the accumulation of arachidonic, eicosapentaenoic, and docosapentaenoic polyunsaturated long-chain fatty acids (LCFAs) in IUGR fetal hearts, which leads to nuclear receptor peroxisome proliferator-activated receptor α (PPARα) transcriptional activation in cardiomyocytes. Also, the enrichment of H3K27ac chromatin marks to PPARα-responsive metabolic genes in IUGR fetal hearts outlines an epigenetic control in the early metabolic energy switch.

CONCLUSION

This study describes a premature and sex-related remodeling of cardiac metabolism in response to an unfavorable intrauterine environment, with specific LCFAs that may serve as predictive effectors leading to IUGR.

Maternal Fructose Intake Exacerbates Cardiac Remodeling in Offspring with Ventricular Pressure Overload

Recent studies demonstrated that metabolic syndrome and cardiovascular diseases could be elicited by developmental programming, which is regulated by prenatal nutritional and environmental stress. In this study, we utilized a rat model to examine the effect of excessive maternal fructose intake during pregnancy and lactation on cardiac development and progression of pressure overload-induced cardiac hypertrophy in offspring. Transverse aortic constriction (TAC) was performed on 3-month-old male offspring to induce ventricular pressure overload. Four weeks post-TAC, echocardiographic assessment as well as histopathological and biochemical examinations were performed on the myocardium of the offspring. Echocardiographic and gross examinations showed that heart weight, interventricular septal thickness in diastole (IVD; d), and left ventricular posterior wall thickness in diastole (LVPW; d) were elevated in offspring with TAC and further increased by maternal fructose exposure (MFE). However, the left ventricular ejection function was not significantly affected. Myocardial histopathological examination revealed that the indices of fibrosis and oxidative stress were higher in offspring with MFE and TAC than those in animals receiving either treatment. Molecular examinations on the myocardium demonstrated an MFE-induced upregulation of p38-MAPK signaling. Next generation sequence (NGS) analysis indicated a modulation of the expression levels of several cardiac hypertrophy-associated genes, including GPR22, Myh7, Nppa, P2RX4, and Npy by MFE. Subsequent RT-PCR indicated that MFE regulated the expression levels of genes responsive to cardiac hypertrophy (i.e., Myh-7, ANP) and oxidative stress (i.e., GR, GPx, and NQO-1). In conclusion, MFE during pregnancy and lactation modulated myocardial gene expression, increased oxidative stress, and exacerbated ventricular pressure overload-induced cardiac remodeling in rat offspring.

Neonatal Growth Restriction Slows Cardiomyocyte Development and Reduces Adult Heart Size

Prematurity is associated with reduced cardiac dimensions and an increased risk of cardiovascular disease. While prematurity is typically associated with ex utero neonatal growth restriction (GR), the independent effect of neonatal GR on cardiac development has not been established. We tested the hypothesis that isolated neonatal GR decreases cardiomyocyte growth and proliferation, leading to long-term alterations in cardiac morphology. C57BL/6 mice were fostered in litters ranging in size from 6 to 12 pups to accentuate normal variation in neonatal growth. Regardless of litter size, GR was defined by a weight below the 10th percentile. On postnatal day 8, Ki67 immunoreactivity, cardiomyocyte nucleation status and cardiomyocyte profile area were assessed. For adult mice, cardiomyocyte area was determined, along with cardiac dimensions by echocardiography and cardiac fibrosis by Masson's trichrome stain. On day 8, cardiomyocytes from GR versus control mice were significantly smaller and less likely to be binucleated with evidence of persistent cell cycle activity. As adults, GR mice continued to have smaller cardiomyocytes, as well as decreased left ventricular volumes without signs of fibrosis. Neonatal GR reduces cardiomyocyte size, delays the completion of binucleation, and leads to long-term alterations in cardiac morphology. Clinical studies are needed to ascertain whether these results translate to preterm infants that must continue to grow and mature in the midst of the increased circulatory demands that accompany their premature transition to an ex utero existence. Anat Rec, 2018. © 2018 Wiley Periodicals, Inc.

Cardiac Development and Transcription Factors: Insulin Signalling, Insulin Resistance, and Intrauterine Nutritional Programming of Cardiovascular Disease

Programming with an insult or stimulus during critical developmental life stages shapes metabolic disease through divergent mechanisms. Cardiovascular disease increasingly contributes to global morbidity and mortality, and the heart as an insulin-sensitive organ may become insulin resistant, which manifests as micro- and/or macrovascular complications due to diabetic complications. Cardiogenesis is a sequential process during which the heart develops into a mature organ and is regulated by several cardiac-specific transcription factors. Disrupted cardiac insulin signalling contributes to cardiac insulin resistance. Intrauterine under- or overnutrition alters offspring cardiac structure and function, notably cardiac hypertrophy, systolic and diastolic dysfunction, and hypertension that precede the onset of cardiovascular disease. Optimal intrauterine nutrition and oxygen saturation are required for normal cardiac development in offspring and the maintenance of their cardiovascular physiology.

Long term effects of fetal undernutrition on rat heart. Role of hypertension and oxidative stress

Background and aims

Fetal undernutrition is a risk factor for heart disease in both genders, despite the protection of women against hypertension development. Using a rat model of maternal undernutrition (MUN) we aimed to assess possible sex differences in the development of cardiac alterations and the implication of hypertension and cardiac oxidative stress.

Methods

Male and female offspring from rats fed ad libitum (control) or with 50% of the normal daily intake during the second half of gestation (MUN) were used. Heart weight/body weight ratio (HW/BW), hemodynamic parameters (anaesthetized rats) and plasma brain natriuretic peptide (BNP, ELISA) were assessed in 21-day, 6-month and 22-month old rats. Plasma testosterone (ELISA) and cardiac protein expression of enzymes related to reactive oxygen species synthesis (p22^phox, xanthine-oxidase) and degradation (catalase, Cu/Zn-SOD, Mn-SOD, Ec-SOD) were evaluated in 21-day and 6-month old rats (Western Blot). Heart structure and function was studied at the age of 22 months (echocardiography).

Results

At the age of 21 days MUN males exhibited significantly larger HW/BW and cardiac p22^phox expression while females had reduced p22^phox expression, compared to their respective sex-matched controls. At the age of 6-months, MUN males showed significantly larger blood pressure and cardiac xanthine-oxidase expression; MUN females were normotensive and had a lower cardiac expression of antioxidant enzymes, compared to their respective sex-matched controls. At the age of 22 months, both MUN males and females showed larger HW/BW and left ventricular mass and lower ejection fraction compared to sex-matched controls; only MUN males exhibited hypertension and a larger plasma BNP compared to aged male controls.

Conclusions

1) During perinatal life females exposed to fetal undernutrition are protected from cardiac alterations, but in ageing they exhibit ventricular hypertrophy and functional loss, like MUN males; 2) cardiac oxidative stress might be implicated in the observed heart alterations in both sexes and 3) the severity of cardiac damage might be greater in males due to hypertension.

Fetal Programming of Cardiac Function and Disease

Fetal programming describes long-term adaptive changes that an organism undergoes in response to an intrauterine insult. This term was coined to describe the increased incidence of adult disease, such as cardiovascular disease, seen among populations that suffered an intrauterine insult. While changes induced by such an insult may be initially beneficial, they can have deleterious long-term effects. Cardiac programming effects can be induced by maternal diet alterations, fetal exposure to increased levels of corticosteroids, chronic fetal hypoxia and anemia, and maternal use of nicotine or cocaine. These stimuli result in a variety of changes in cardiac function and gene expression, many of which persist into adulthood. A possible mediator of these changes is an alteration in the DNA methylation pattern of the cardiomyocytes. This review gives an overview of the changes that have been observed in the heart in response to various programming stimuli and potential programming mechanisms.

IGF-2R-Gαq signaling and cardiac hypertrophy in the low-birth-weight lamb

The cardiac insulin-like growth factor 2 receptor (IGF-2R) can induce cardiomyocyte hypertrophy in a heterotrimeric G protein receptor-coupled manner involving αq (Gαq) or αs (Gαs). We have previously shown increased left ventricular weight and cardiac IGF-2 and IGF-2R gene expression in low-birth-weight (LBW) compared with average-birth-weight (ABW) lambs. Here, we have investigated the cardiac expression of IGF-2 gene variants, the degree of histone acetylation, and the abundance of proteins in the IGF-2R downstream signaling pathway in ABW and LBW lambs. Samples from the left ventricle of ABW and LBW lambs were collected at 21 days of age. There was increased phospho-CaMKII protein with decreased HDAC 4 abundance in the LBW compared with ABW lambs. There was increased GATA 4 and decreased phospho-troponin I abundance in LBW compared with ABW lambs, which are markers of pathological cardiac hypertrophy and impaired or reduced contractility, respectively. There was increased histone acetylation of H3K9 at IGF-2R promoter and IGF-2R intron 2 differentially methylated region in the LBW lamb. In conclusion, histone acetylation of IGF-2R may lead to increased IGF-2R mRNA expression and subsequently mediate Gαq signaling early in life via CaMKII, resulting in an increased risk of left ventricular hypertrophy and cardiovascular disease in adult life.

The influence of hypoxia during different pregnancy stages on cardiac collagen accumulation in the adult offspring

We evaluated whether the timing of maternal hypoxia during pregnancy influenced cardiac extracellular matrix accumulation in the adult offspring. Rats in different periods of pregnancy were assigned to maternal hypoxia or control groups. Maternal hypoxia from day 3 to 21 of pregnancy or day 9 to 21 of pregnancy increased collagen I and collagen III expression in the left ventricle of adult offspring (both P < 0.05). Maternal hypoxia from day 15 to 21 of pregnancy had no effect on adult collagen levels. Our results indicate that maternal hypoxia at critical windows of cardiovascular development can induce pathological cardiac remodeling in the adult rat offspring.

Impaired myocardial performance in a normotensive rat model of intrauterine growth restriction

BACKGROUND

Intrauterine growth restriction (IUGR) is an important risk factor for cardiovascular disease. Previous studies revealed altered myocardial matrix composition after IUGR. We hypothesized that IUGR is accompanied by compromised myocardial performance independently from arterial hypertension.

METHODS

IUGR was induced in Wistar rats by maternal protein restriction, and hearts of male offspring were studied using echocardiography, immunohistochemistry, real-time PCR, and western blot analysis.

RESULTS

At day 70 of life, in the absence of arterial hypertension (mean arterial blood pressure: 101.3 ± 7.1 mmHg in IUGR vs. 105.3 ± 4.6 mmHg in controls, not significant (NS)), echocardiography showed a reduced contractility (ejection fraction: 65.4 ± 1.8% in IUGR vs. 82.2 ± 1.5% in controls, P < 0.001) of a more distensible myocardium in IUGR rats. Altered expression patterns of myosin chains and titin isoforms and increased expression levels of atrial natriuretic peptide, Na/K-ATPase, and β-adrenergic receptor 1 were detected. A higher number of cardiac fibroblasts and vascular cross-sections were observed in IUGR rats, accompanied by elevated expression of hypoxia inducible factor 1 target genes, such as vascular endothelial growth factor and its receptors.

CONCLUSION

We observed a blood pressure-independent impairment of myocardial function after IUGR, which possibly favors cardiovascular disease later in life. Some IUGR-induced myocardial changes (e.g., sarcomeric components) may partly explain the compromised cardiac performance, whereas others (e.g., elevated vascular supply) reflect compensatory mechanisms.

Maternal obesity and the developmental programming of hypertension: a role for leptin

Mother-child cohort studies have established that both pre-pregnancy body mass index (BMI) and gestational weight gain are independently associated with cardio-metabolic risk factors in young adult offspring, including systolic and diastolic blood pressure. Animal models in sheep and non-human primates provide further evidence for the influence of maternal obesity on offspring cardiovascular function, whilst recent studies in rodents suggest that perinatal exposure to the metabolic milieu of maternal obesity may permanently change the central regulatory pathways involved in blood pressure regulation. Leptin plays an important role in the central control of appetite, is also involved in activation of efferent sympathetic pathways to both thermogenic and non-thermogenic tissues, such as the kidney, and is therefore implicated in obesity-related hypertension. Leptin is also thought to have a neurotrophic role in the development of the hypothalamus, and altered neonatal leptin profiles secondary to maternal obesity are associated with permanently altered hypothalamic structure and function. In rodent studies, maternal obesity confers persistent sympathoexcitatory hyper-responsiveness and hypertension acquired in the early stages of development. Experimental neonatal hyperleptinaemia in naive rat pups provides further evidence of heightened sympathetic tone and proof of principle that hyperleptinaemia during a critical window of hypothalamic development may directly lead to adulthood hypertension. Insight from these animal models raises the possibility that early-life exposure to leptin in humans may lead to early onset essential hypertension. Ongoing mother-child cohort and intervention studies in obese pregnant women provide a unique opportunity to address associations between maternal obesity and offspring cardiovascular function. The goal of the review is to highlight the potential importance of leptin in the developmental programming of hypertension in obese pregnancy.

Prenatal hypoxia programs changes in β-adrenergic signaling and postnatal cardiac contractile dysfunction

Prenatal hypoxia leads to an increased risk of adult cardiovascular disease. We have previously demonstrated a programming effect of prenatal hypoxia on the cardiac β-adrenergic (βAR) response. The aim of this study was to determine 1) whether the decrease in βAR sensitivity in prenatally hypoxic 5-wk old chicken hearts is linked to changes in β1AR/β2ARs, Gαi expression and cAMP accumulation and 2) whether prenatal hypoxia has an effect on heart function in vivo. We incubated eggs in normoxia (N, 21% O2) or hypoxia from day 0 (H, 14% O2) and raised the posthatchlings to 5 wk of age. Cardiac β1AR/β2ARs were assessed through competitive binding of [(3)H]CGP-12177 with specific β1AR or β2AR blockers. Gαs and Gαi proteins were assessed by Western blot and cAMP accumulation by ELISA. Echocardiograms were recorded in anesthetized birds to evaluate diastolic/systolic diameter and heart rate and tissue sections were stained for collagen. We found an increase in relative heart mass, β1ARs, and Gαs in prenatally hypoxic hearts. cAMP levels after isoproterenol stimulation and collagen content was not changed in H compared with N, but in vivo echocardiograms showed systolic contractile dysfunction. The changes in βAR and G protein subtypes may be indicative of an early compensatory stage in the progression of cardiac dysfunction, further supported by the cardiac hypertrophy and systolic contractile dysfunction. We suggest that it is not the changes in the proximal part of the βAR system that causes the decreased cardiac contractility, but Ca(2+) handling mechanisms further downstream in the βAR signaling cascade.

Coenzyme Q10 prevents accelerated cardiac aging in a rat model of poor maternal nutrition and accelerated postnatal growth

Studies in human and animals have demonstrated that nutritionally induced low birth-weight followed by rapid postnatal growth increases the risk of metabolic syndrome and cardiovascular disease. Although the mechanisms underlying such nutritional programming are not clearly defined, increased oxidative-stress leading to accelerated cellular aging has been proposed to play an important role. Using an established rodent model of low birth-weight and catch-up growth, we show here that post-weaning dietary supplementation with coenzyme Q10, a key component of the electron transport chain and a potent antioxidant rescued many of the detrimental effects of nutritional programming on cardiac aging. This included a reduction in nitrosative and oxidative-stress, telomere shortening, DNA damage, cellular senescence and apoptosis. These findings demonstrate the potential for postnatal antioxidant intervention to reverse deleterious phenotypes of developmental programming and therefore provide insight into a potential translatable therapy to prevent cardiovascular disease in at risk humans.

Salt intake during pregnancy alters offspring's myocardial structure

BACKGROUND AND AIM

To evaluate the effects of low or high salt intake during pregnancy on left ventricle of adult male offspring.

METHODS AND RESULTS

Low- (LS, 0.15%), normal- (NS, 1.3%) or high-salt (HS, 8% NaCl) diet was given to Wistar rats during pregnancy. During lactation all dams received NS as well as the offspring after weaning. To evaluate cardiac response to salt overload, 50% of each offspring group was fed a high-salt (hs, 4% NaCl) diet from the 21st to the 36th week of age (LShs, NShs, HShs). The remaining 50% was maintained on NS (LSns, NSns and HSns). Echocardiography was done at 20 and 30 weeks of age. Mean blood pressure (MBP), histology and left ventricular angiotensin II content (AII) were analyzed at 36 weeks of age. Interventricular septum, left ventricular posterior wall and relative wall thickness increased from the 20th to the 30th week of age only in HShs, cardiomyocyte mean volume was higher in HShs compared to NShs, LShs and HSns. AII and left ventricular fibrosis were not different among groups.

CONCLUSIONS

HS during pregnancy programs adult male offspring to a blood pressure and angiotensin II independent concentric left ventricular hypertrophy, with no fibrosis, in response to a chronic high-salt intake.

Early origins of heart disease: low birth weight and determinants of cardiomyocyte endowment

1. World-wide epidemiological and experimental animal studies demonstrate that adversity in fetal life, resulting in intrauterine growth restriction, programmes the offspring for a greater susceptibility to ischaemic heart disease and heart failure in adult life. 2. After cardiogenesis, cardiomyocyte endowment is determined by a range of hormones and signalling pathways that regulate cardiomyocyte proliferation, apoptosis and the timing of multinucleation/terminal differentiation. 3. The small fetus may have reduced cardiomyocyte endowment owing to the impact of a suboptimal intrauterine environment on the signalling pathways that regulate cardiomyocyte proliferation, apoptosis and the timing of terminal differentiation.

Intrauterine growth restriction coupled with hyperglycemia: effects on cardiac structure in adult rats

BACKGROUND

Intrauterine growth restriction (IUGR) has been linked to heart disease in adulthood. Hence the IUGR heart is likely to be vulnerable to diabetic heart disease. The aim of this study was to examine the effect of induction of type 1 diabetes on myocardial collagen deposition and cardiac function in adult rats with a history of IUGR, after controlling blood glucose levels.

METHODS

IUGR was induced by protein restriction in the pregnant female rat. When the offspring were 24 wk of age, diabetes was induced in male IUGR and non-IUGR rats by means of streptozotocin; insulin injections were used to maintain blood glucose levels at a mild (7-10 mmol/l; n = 8 per group) or moderate level (10-15 mmol/l; n = 8 per group). Echocardiography and cardiac morphology analyses were carried out when the rats were 32 wk of age.

RESULTS

IUGR offspring exhibited cardiac hypertrophy at 32 wk, including a thicker posterior wall and increased interstitial fibrosis in the left ventricle. Hyperglycemia led to an increase in heart size and myocardial fibrosis. The response to hyperglycemia was not different between IUGR and non-IUGR rats; however, cardiac fibrosis was greatest when diabetes was present along with a history of IUGR. In general, maintaining blood glucose levels at a mildly hyperglycemic level attenuated the adverse effects of hyperglycemia but did not reverse the fibrosis.

CONCLUSION

Exacerbated fibrosis in hyperglycemic hearts of IUGR offspring may lead to long-term cardiac dysfunction.

Regulation of the sodium pump during cardiomyocyte adaptation to pregnancy

Regulation of the sodium pump during normal pregnancy and its effect on the function of cardiomyocytes is poorly understood. Our objective was to evaluate the possible implication of the Na(+)-K(+)-ATPase, the sodium pump which controls cellular ionic and metabolic homeostasis, in the adaptations of cardiomyocytes to normal pregnancy. We have used Western blots and patch-clamp measurements to identify changes in the sodium pump proteins. Confocal microscopy was applied to estimate intracellular sodium concentration. Time-resolved spectroscopy was employed to measure mitochondrial NAD(P)H fluorescence and estimate oxidative metabolic state. Optical microscopy was adopted to study the contractility responses of cardiomyocytes. Cells from non-pregnant and pregnant rats (1 day prior parturition) were studied. Our results showed lower protein expression of the α1 Na(+)-K(+)-ATPase isoform in cardiomyocytes in pregnant rats, decreased sodium pump membrane current and elevated steady-state sodium concentration. In addition, ouabain, the inhibitor of the sodium pump capable of increasing cardiomyocyte contractility in non-pregnant rats in a concentration-dependent manner, failed to affect cell contractions in pregnant rats. We also noted modified responsiveness of the mitochondrial metabolic state to ouabain in cardiac cells. The gathered data confirmed that in pregnant rats, the sodium pump protein content and transmembrane flux are decreased, while the sensitivity of cardiomyocyte contractility and the sensitivity of mitochondrial metabolic redox state to ouabain are modified, pointing to regulation of the Na(+)-K(+)-ATPase during cardiac cell adaptations to normal pregnancy.

The effect of feto-maternal size and childhood growth on left ventricular mass and arterial stiffness in Afro-Caribbean children

We hypothesized that maternal size, fetal size and childhood growth are associated with childhood blood pressure, left ventricular mass (LVM) and arterial stiffness. The Vulnerable Windows Cohort is a longitudinal study of 569 mothers and their offspring. Anthropometry was measured on each child at birth, at 6 weeks, once in 3 months upto 2 years and then every 6 months. Blood pressure and body composition were assessed in 185 children (age 11.5 years) and echocardiography performed. LVM was not associated with maternal size after adjustment for child's weight. LVM was significantly associated with faster growth in childhood and with current weight, fat mass and lean mass. Systolic blood pressure was not related to maternal, fetal or newborn anthropometry, but was positively associated with infant and childhood growth, as well as current body size and fat mass. The pulse pressure/stroke volume ratio (an index of arterial stiffness) was inversely associated with maternal size, placental volume at 20 weeks, fetal size at 35 weeks and childhood growth even after adjustment for current weight. In conclusion, LVM in childhood is positively associated with maternal height, child's current size and rate of growth. Arterial stiffness is inversely related to maternal, fetal and placental size as well as growth throughout childhood.

Role of fetal programming in the development of hypertension

Epidemiological studies have suggested that size at birth contributes to increased cardiovascular disease (CVD) risk in later life. Findings from experimental studies are providing insight into the mechanisms linking impaired fetal growth and the increased risk of CVD and hypertension in adulthood. This article summarizes potential mechanisms involved in the fetal programming of hypertension and CVD, including alterations in the organs and regulatory systems critical to long-term control of sodium and volume homeostasis.

Fetal adrenal gland alterations in a rat model of adverse intrauterine environment

By feeding a low-sodium diet to dams over the last third of gestation, we have developed an animal model of intrauterine growth restriction (IUGR). Given that fetal adrenal development and maturation occur during late gestation in rats, the aim of this study was to evaluate the expression of proteins and enzymes involved in steroidogenesis and catecholamine synthesis in adrenal glands from IUGR fetuses. A gene microarray was performed to investigate for alteration in the pathways participating in hormone production. Results show that increased aldosterone serum concentrations in IUGR fetuses were associated with higher mRNA adrenal levels of angiotensin II receptor type 1 (AT(1)R) and cytochrome P450 aldosterone synthase in response to decreased serum sodium content. Conversely, reduced serum corticosterone concentrations in these fetuses appear to result from alterations in gene expression involved in cholesterol metabolism, such as the augmented apolipoprotein E levels, and in steroidogenesis, like the decreased levels of cytochrome P45011beta-hydroxylase. Furthermore, increased AT(2)R expression and the presence of hypoxia and oxidative stress may, in turn, explain the higher adrenal mRNA levels of enzymes involved in catecholamine synthesis. Despite this increase, catecholamine adrenal content was reduced in males and was similar in females compared with sex-matched controls, suggesting higher catecholamine secretion. This could be associated with the induction of genes involved in inflammation-related, acute-phase response in IUGR fetuses. All of these alterations could have long-lasting health effects and may, hence, be implicated in the pathogenesis of increased blood pressure and cardiac hypertrophy observed in IUGR adult animals from this model.

Renal and cardiac Na+-K +-ATPase and aconitase in a rat model of fetal programming

Fetal programming of adult disease is an area of research that has gained considerable attention. Epidemiological studies suggest that adverse intrauterine environment in fetal life is associated with a higher incidence of hypertension and coronary disease. Several mechanisms could contribute to these diseases and be regulated in a tissue-specific manner. The Na(+)-K(+)-ATPase, a membrane-bound enzyme, maintains the Na(+) and K(+) gradients across the plasma membrane of animal cells and therefore provides a mechanism for cell function regulation. Furthermore, in an in vitro model of cardiac hypertrophy, a decrease in the activity of the tricarboxylic acid (TCA) cycle enzyme, aconitase, was observed. We have shown that in our model of fetal programming, these two enzymes were regulated differently in heart and kidney of adult females.

Developmental programming resulting from maternal obesity in mice: effects on myocardial ischaemia-reperfusion injury

A comprehensive number of epidemiological and animal studies suggest that prenatal and early life events are important determinants for disorders later in life. Among them, prenatal stress (i.e. stress experienced by the pregnant mother with impact on the fetal ontogeny) has clear programming effects on the cardiovascular system. A fetus developing in adverse conditions becomes an adult who is susceptible to disease, which may include hypertension, insulin resistance, altered blood lipid levels and cardiovascular disease. Recent evidence demonstrates that maternal programming can occur in the absence of other adverse environmental factors. Obesity, which is becoming a problem of large proportions in Western countries, is a possible cause of programming. With over 30% of the population of the USA currently obese, many mothers suffer from obesity during their child-bearing years (in fact, these conditions are often aggravated during pregnancy). One of the targets of programming is the cardiovascular system, and reported consequences include hypertension, endothelial dysfunction and vascular abnormalities. The overall goal of our study was to investigate the susceptibility of the heart to ischaemia-reperfusion in an animal model of maternal obesity. Our data demonstrate that normal (non-mutant) offspring from obese agouti mouse dams had an increased susceptibility to ischaemia-reperfusion injury. These data may provide insights into the long-term cardiovascular consequences of programming.

Maternal dietary supplementation with saturated, but not monounsaturated or polyunsaturated fatty acids, leads to tissue-specific inhibition of offspring Na+,K+-ATPase

In rats, a maternal diet rich in lard is associated with reduced Na(+),K(+)-ATPase activity in adult offspring kidney. We have addressed the role of different fatty acids by evaluating Na(+),K(+)-ATPase activity in offspring of dams fed diets rich in saturated (SFA), monounsaturated (MUFA) or polyunsaturated (PUFA) fatty acids. Female Sprague-Dawley rats were fed, during pregnancy and suckling, a control diet (4% w/w corn oil) or a fatty acid supplemented diet (24% w/w). Offspring were reared on chow (4% PUFA) and studied at 6 months. mRNA expression (real-time PCR) of Na(+),K(+)-ATPase alpha subunit and protein expression of Na(+),K(+)-ATPase subunits (Western blot) were assessed in kidney and brain. Na(+),K(+)-ATPase activity was reduced in kidney (P < 0.05 versus all groups) and brain (P < 0.05 versus control and MUFA offspring) of the SFA group. Neither Na(+),K(+)-ATPase alpha1 subunit mRNA expression, nor protein expression of total alpha, alpha1, alpha2, alpha3 or beta1 subunits were significantly altered in kidney in any dietary group. In brains of SFA offspring alpha1 mRNA expression (P < 0.05) was reduced compared with MUFA and PUFA offspring, but not controls. Also in brain, SFA offspring demonstrated reduced (P < 0.05) alpha1 subunit protein and increased phosphorylation (P < 0.05) of the Na(+),K(+)-ATPase modulating protein phospholemman at serine residue 63 (S63 PLM). Na(+),K(+)-ATPase activity was similar to controls in heart and liver. In utero and neonatal exposure to a maternal diet rich in saturated fatty acids is associated with altered activity and expression of Na(+),K(+)-ATPase in adulthood, but mechanisms appear tissue specific.

Maternal fish oil supplementation benefits programmed offspring from rat dams fed low-protein diet

OBJECTIVE

We hypothesized that maternal fish oil supplementation would prevent the programming of offspring cardiovascular alterations.

STUDY DESIGN

Forty rats were fed during the perinatal period with normal-protein (NP) diet (19%) or low-protein (LP) diet (5%) and also received daily fish oil supplement (Fo). Offspring were divided into male and female NP, NP plus Fo, and LP and LP plus Fo groups (n = 5, each) until 6 months old. Cardiac structure was examined.

RESULTS

Both LP sexes had mild hypertension, but Fo supplementation minimized hypertension. The left ventricle was thicker in the LP groups and less thick in the LP plus Fo groups. The male LP had significantly fewer intramyocardial microcirculation, whereas the male LP plus Fo had 90% more microcirculation than the LP group. The LP group had significantly higher interstitial fibrosis, compared with the NP groups.

CONCLUSION

Postnatal hypertension and collateral cardiovascular adverse remodeling were programmed by perinatal LP diet, whose outcomes were alleviated by maternal fish oil supplementation.

From integrative signalling to metabolic disorders

The adrenal cortex undergoes constant dynamic structural changes, a key element in ensuring integrative functionality of the gland. Studies have shown that the cellular environment can modulate cell functions such as proliferation and steroid secretion. For example, 3-day treatment with angiotensin II promotes protein synthesis with a concomitant decrease in proliferation of glomerulosa cells, when cultured on fibronectin, but not on collagen IV or laminin. These effects involve close interaction between cytoskeleton-associated proteins and activation of p42/p44mapk and p38 MAPK pathways. On the other hand, adrenocorticotropin hormone (ACTH), which is clearly the most potent stimulus of fasciculata cells, induces specific modulation of targeted proteins, when cells are cultured on collagen IV, but not on fibronectin or laminin. In particular, ACTH treatment leads to increased expression of Seladin-1 and induces the relocalization of Seladin-1 from the cytoplasm to the nucleus, both in vivo and in culture conditions, in adult rats and in human fetal adrenal glands. As a whole, these results indicate that Seladin-1, together with collagen IV, is able to modulate ACTH responsiveness. Hence, Seladin-1 may participate in the regulation of steroidogenesis when localized in the cytoplasm, while conversely protecting cells against oxidative stress generated by intense ACTH stimulation when massively localized in the nucleus.

Endothelial superoxide production is altered in sheep programmed by early gestation dexamethasone exposure

BACKGROUND

Animal models have demonstrated that maternal undernutrition or early gestation glucocorticoid exposure induces endothelial dysfunction in the offspring.

OBJECTIVES

We sought to determine whether early gestation dexamethasone (DEX) exposure is further associated with increased vascular superoxide anion production.

METHODS

DEX (0.28 mg/kg/day i.v. for 48 h) was administered to pregnant ewes at 27-28 days' gestation (term 145 days). Tissues were harvested from DEX-exposed and control lambs at 125 days' gestation (n = 6 for each group) and 4 months following delivery (n = 9 and 12, respectively).

RESULTS

By lucigenin-enhanced chemiluminescence, coronary and mesenteric arteries from DEX-exposed fetuses exhibited diminished basal superoxide production (both p < 0.01). Similarly, DEX-exposed carotid arteries from 4-month-old lambs had decreased superoxide production (p < 0.01) that localized to the endothelium by endothelial cell culture and dihydroethidium fluorescence. In contrast, DEX-exposed coronary arteries from the 4-month-old sheep had increased superoxide production (p < 0.05). Although early gestation DEX exposure did not alter lipid peroxidation, DEX exposure was associated with significantly increased renal and cerebral cortex aconitase activity (consistent with decreased protein oxidation). These changes occurred in the absence of alterations in renal cortex superoxide dismutase activity.

CONCLUSIONS

We conclude that in a DEX-exposure model of fetal programming, endothelial superoxide production and protein oxidation are decreased in the mesenteric and carotid circulation. This contrasts with the postnatal coronary artery-specific increase in superoxide production.

Renal and cardiac oxidative/nitrosative stress in salt-loaded pregnant rat

Sodium supplementation given for 1 wk to nonpregnant rats induces changes that are adequate to maintain renal and circulatory homeostasis as well as arterial blood pressure. However, in pregnant rats, proteinuria, fetal growth restriction, and placental oxidative stress are observed. Moreover, the decrease in blood pressure and expansion of circulatory volume, normally associated with pregnancy, are prevented by high-sodium intake. We hypothesized that, in these pregnant rats, a loss of the balance between prooxidation and antioxidation, particularly in kidneys and heart, disturbs the normal course of pregnancy and leads to manifestations such as gestational hypertension. We thus investigated the presence of oxidative/nitrosative stress in heart and kidneys following high-sodium intake in pregnant rats. Markers of this stress [8-isoprostaglandin F(2alpha) (8-iso-PGF(2alpha)) and nitrotyrosine], producer of nitric oxide [nitric oxide synthases (NOSs)], and antioxidants [superoxide dismutase (SOD) and catalase] were measured. Then, molecules (Na(+)-K(+)-ATPase and aconitase) or process [apoptosis (Bax and Bcl-2), inflammation (monocyte chemoattractant protein-1, connective tissue growth factor, and TNF-alpha)] susceptible to free radicals was determined. In kidneys from pregnant rats on 1.8% NaCl-water, NOSs, apoptotic index, and nitrotyrosine expression were increased, whereas Na(+)-K(+)-ATPase mRNA and activity were decreased. In the left cardiac ventricle of these rats, heightened nitrotyrosine, 8-iso-PGF(2alpha), and catalase activity together with reduced endothelial NOS protein expression and SOD and aconitase activities were observed. These findings suggest that oxidative/nitrosative stress in kidney and left cardiac ventricle destabilizes the normal course of pregnancy and could lead to gestational hypertension.

Uteroplacental insufficiency increases p53 phosphorylation without triggering the p53-MDM2 functional circuit response in the IUGR rat kidney

Uteroplacental insufficiency (UPI) leads to intrauterine growth restriction (IUGR), which predisposes infants toward renal insufficiency early in life and increases the risk of kidney-related adult morbidities, such as hypertension. This compromised in utero environment has been demonstrated to impair nephrogenesis, as evidenced by a reduced nephron endowment in humans and in rats rendered IUGR by UPI. Concordantly, we have observed that IUGR rats have increased kidney p53 protein levels associated with increased apoptosis. Several factors can regulate p53 gene expression and activity, including posttranslational modifications and protein-protein interactions in the cell. Among these, two important mechanisms are 1) phosphorylation of the amino terminal serine 15 [phospho-p53 (Ser15)], which increases p53 stability and apoptotic activity, and 2) the murine double-minute (MDM2) functional circuit that limits further p53-induced apoptosis by promoting proteosomal degradation of p53. We hypothesize that UPI induces an increase in phospho-p53 (Ser15) in association with an absent MDM2 response, predisposing the kidney to increased apoptosis. To test our hypothesis, we induced IUGR through bilateral uterine artery ligation of the pregnant rat. UPI significantly increased phospho-p53 (Ser15), as well as ataxia teleangiectasia-mutated kinase/A-T-related kinase and dsDNA-activated protein kinase kinase levels, which induce phosphorylation of p53. In contrast, UPI induced no increase in kidney MDM2 mRNA and protein levels in IUGR pups. We conclude that among multiple mechanisms that affect nephrogenesis, UPI induces an increase in p53 phosphorylation without a corresponding increase in MDM2 expression, and we speculate that this response may contribute to the increased apoptosis previously described in the IUGR kidney.

Gender-related changes in magnetocardiographically determined fetal cardiac time intervals in intrauterine growth retardation

Prenatal growth deficiencies as well as gender have been associated with cardiovascular disease in later life. It is also known that the duration of fetal cardiac time intervals (CTI) are dependent on fetal development. The aim of this work was to examine the relationship between fetal CTI in healthy and intrauterine growth retardation (IUGR) fetuses, taking gender into account. A total of 269 magnetocardiograms (MCG) were obtained in 47 healthy and 27 IUGR pregnancies. In each signal-averaged MCG, durations of CTI were determined. Age- and heart rate-corrected values were compared between normal and IUGR fetuses separately with respect to gender. Overall, there was an association between atrial and ventricular conduction times and estimated fetal body weight. In female fetuses, IUGR was associated with shorter P WAVE, PQ segment, PR interval, and QRS complex and longer STT and QT intervals. For males, this was so only for P wave, QRS complex, and STT interval. The shortening of conduction times in IUGR may be explained by reduced cardiac muscle mass associated with lower body weight. On the other hand, the gender-specific differences, particularly in the IUGR fetuses may be due to hormonal factors.

Role of nutrition in the development of the fetal cardiovascular system

Emerging evidence demonstrates that heart disease may originate during fetal development. This review will focus on the role of maternal nutrition in the development of the fetal cardiovascular system. Emphasis will be placed upon the concept that nutritional inadequacies during gestation may be major programming stimuli that alter fetal cardiac, as well as vascular, physiology and predispose an individual to cardiovascular abnormalities in postnatal life. It is hypothesized that this research area will yield new information, resulting in improved fetal nutrition, growth and development through efficient maternal nutrition before and during pregnancy and will form the basis for nutritional strategies for the primary prevention of cardiovascular disease.

Hypoxia or nutrient restriction during pregnancy in rats leads to progressive cardiac remodeling and impairs postischemic recovery in adult male offspring

Intrauterine growth restriction (IUGR) increases the risk of developing adult-onset cardiovascular disease. We hypothesized that IUGR resulting from maternal hypoxia or nutrient restriction during late gestation will produce cardiac remodeling and impair cardiac recovery after ischemia/reperfusion (I/R) in adult male offspring aged 4 or 7 mo. Sprague-Dawley rats were randomized on day 15 of pregnancy to hypoxia (IUGR-H, 12% oxygen), nutrient restriction (IUGR-NR, 40% of control diet) or control (room air) groups. In 4-mo IUGR-H offspring, left ventricular wt/body wt ratio (LVW/BW) and right ventricular wt/BW ratio (RVW/BW) increased, in association with increased collagen I and III expression, beta and alpha myosin heavy chain (beta/alphaMHC) ratio, and decreased matrix metalloproteinase (MMP)-2 activity compared to the other groups. Left ventricular end diastolic pressure was higher in perfused hearts. Functional recovery after I/R was remarkably reduced (10+/-3%) compared to both control (39+/-5%) and IUGR-NR rats (32+/-4%). At 7 mo, both IUGR-H and IUGR-NR offspring had increased LVW/BW, collagen I and III, beta/alpha MHC ratio, and decreased cardiac recovery and MMP-2 activity compared to control. These findings suggest that hypoxia or undernutrition during development leads to pathological cardiac remodeling, diastolic dysfunction, and increased sensitivity to ischemic injury during adult life.

Maternal nutrient restriction and the fetal left ventricle: decreased angiotensin receptor expression

BACKGROUND

Adequate maternal nutrition during gestation is requisite for fetal nutrition and development. While a large group of epidemiological studies indicate poor fetal nutrition increases heart disease risk and mortality in later life, little work has focused on the effects of impaired maternal nutrition on fetal heart development. We have previously shown that 50% global nutrient restriction from 28-78 days of gestation (early to mid-pregnancy; term = 147 days) in sheep at mid-gestation retards fetal growth while protecting growth of heart and results in hypertensive male offspring at nine months of age. In the present study, we evaluate LV gene transcription using RNA protection assay and real-time reverse transcriptase polymerase chain reaction, and protein expression using western blot, of VEGF and AT1 and AT2 receptors for AngII at mid-gestation in fetuses from pregnant ewes fed either 100% (C) or 50% (NR) diet during early to mid-gestation.

RESULTS

No difference between the NR (n = 6) and C (n = 6) groups was found in gene transcription of the AngII receptors. Immunoreactive AT1 (1918.4 +/- 154.2 vs. 3881.2 +/- 494.9; P < 0.01) and AT2 (1729.9 +/- 293.6 vs. 3043.3 +/- 373.2; P < 0.02) was decreased in the LV of NR fetuses compared to C fetuses. The LV of fetuses exposed to NR had greater transcription of mRNA for VEGF (5.42 +/- 0.85 vs. 3.05 +/- 0.19; P < 0.03) than respective C LV, while no change was observed in immunoreactive VEGF.

CONCLUSION

The present study demonstrates that VEGF, AT1 and AT2 message and protein are not tightly coupled, pointing to post-transcriptional control points in the mid gestation NR fetus. The present data also suggest that the role of VEGF and the renin-angiotensin system receptors during conditions inducing protected cardiac growth is distinct from the role these proteins may play in normal fetal cardiac growth. The present findings may help explain epidemiological studies that indicate fetuses with low birth weight carry an increased risk of mortality from coronary and cardiovascular disease, particularly if these individuals have reduced cardiovascular reserve due to an epigenetic decrease in vascularization.