Fetal exposure to a maternal low-protein diet is associated with altered left ventricular pressure response to ischaemia-reperfusion injury

Periconceptional alcohol alters in vivo heart function in ageing female rat offspring: Possible involvement of oestrogen receptor signalling

NEW FINDINGS

What is the central question of this study? What are the cardiovascular consequences of periconceptual ethanol on offspring throughout the lifespan? What is the main finding and its importance? It is shown for the first time that periconceptional alcohol has sex-specific effects on heart growth, with ageing female offspring exhibiting decreased cardiac output. Altered in vivo cardiac function in ageing female offspring may be linked to changes in cardiac oestrogen receptor expression.

ABSTRACT

Alcohol exposure throughout gestation is detrimental to cardiac development and function. Although many women decrease alcohol consumption once aware of a pregnancy, exposure prior to recognition is common. We, therefore, examined the effects of periconceptional alcohol exposure (PC:EtOH) on heart function, and explored mechanisms that may contribute. Female Sprague-Dawley rats received a liquid diet ±12.5% v/v ethanol from 4 days prior to mating until 4 days after mating (PC:EtOH). Cardiac function was assessed via echocardiography, and offspring were culled at multiple time points for assessment of morphometry, isolated heart and aortic ring function, protein and transcriptional changes. PC:EtOH-exposed embryonic day 20 fetuses (but not postnatal offspring) had larger hearts relative to body weight. Ex vivo analysis of hearts at 5-7 months old (mo) indicated no changes in coronary function or cardiac ischaemic tolerance, and apparently improved ventricular compliance in PC:EtOH females (compared to controls). At 12 mo, vascular responses in isolated aortic rings were unaltered by PC:EtOH, whilst echocardiography revealed reduced cardiac output in female but not male PC:EtOH offspring. At 19 mo, left ventricular transcript and protein for type 1 oestrogen receptor (ESR1), HSP90 transcript and plasma oestradiol levels were all elevated in female PC:EtOH exposed offspring. Summarising, PC:EtOH adversely impacts in vivo heart function in mature female offspring, associated with increased ventricular oestrogen-related genes. PC:EtOH may thus influence age-related heart dysfunction in females through modulation of oestrogen signalling.

Animal Foetal Models of Obesity and Diabetes - From Laboratory to Clinical Settings

The prenatal period, during which a fully formed newborn capable of surviving outside its mother's body is built from a single cell, is critical for human development. It is also the time when the foetus is particularly vulnerable to environmental factors, which may modulate the course of its development. Both epidemiological and animal studies have shown that foetal programming of physiological systems may alter the growth and function of organs and lead to pathology in adulthood. Nutrition is a particularly important environmental factor for the pregnant mother as it affects the condition of offspring. Numerous studies have shown that an unbalanced maternal metabolic status (under- or overnutrition) may cause long-lasting physiological and behavioural alterations, resulting in metabolic disorders, such as obesity and type 2 diabetes (T2DM). Various diets are used in laboratory settings in order to induce maternal obesity and metabolic disorders, and to alter the offspring development. The most popular models are: high-fat, high-sugar, high-fat-high-sugar, and cafeteria diets. Maternal undernutrition models are also used, which results in metabolic problems in offspring. Similarly to animal data, human studies have shown the influence of mothers' diets on the development of children. There is a strong link between the maternal diet and the birth weight, metabolic state, changes in the cardiovascular and central nervous system of the offspring. The mechanisms linking impaired foetal development and adult diseases remain under discussion. Epigenetic mechanisms are believed to play a major role in prenatal programming. Additionally, sexually dimorphic effects on offspring are observed. Therefore, further research on both sexes is necessary.

Sex-dependent effects of prenatal food and protein restriction on offspring physiology in rats and mice: systematic review and meta-analyses

BACKGROUND

Males and females may experience different effects of early-life adversity on life-long health. One hypothesis is that male foetuses invest more in foetal growth and relatively less in placental growth, and that this makes them susceptible to poor nutrition in utero, particularly if nutrition is reduced part-way through gestation.

OBJECTIVES

Our objectives were to examine whether (1) food and/ or protein restriction in rats and mice has consistent sex-dependent effects, (2) sex-dependency differs between types of outcomes, and (3) males are more severely affected when restriction starts part-way through gestation.

DATA SOURCES

PubMed and Web of Science were searched to identify eligible studies.

STUDY ELIGIBILITY CRITERIA

Eligible studies described controlled experiments that restricted protein or food during gestation in rats or mice, examined physiological traits in offspring from manipulated pregnancies, and tested whether effects differed between males and females.

RESULTS

Our search identified 292 articles, of which the full texts of 72 were assessed, and 65 were included for further synthesis. A majority (50) used Wistar or Sprague-Dawley rats and so these were the primary focus. Among studies in which maternal diet was restricted for the duration of gestation, no type of trait was consistently more severely affected in one particular sex, although blood pressure was generally increased in both sexes. Meta-analysis found no difference between sexes in the effect of protein restriction throughout gestation on blood pressure. Among studies restricting food in the latter half of gestation only, there were again few consistent sex-dependent effects, although three studies found blood pressure was increased in males only. Meta-analysis found that food restriction in the second half of gestation increased adult blood pressure in both sexes, with a significantly greater effect in males. Birthweight was consistently reduced in both sexes, a result confirmed by meta-analysis.

CONCLUSIONS

We found little support for the hypotheses that males are more affected by food and protein restriction, or that effects are particularly severe if nutrition is reduced part-way through gestation. However, less than half of the studies tested for sex by maternal diet interactions to identify sex-dependent effects. As a result, many reported sex-specific effects may be false positives.

Prenatal therapeutics and programming of cardiovascular function

Cardiovascular diseases (CVD) are a leading cause of mortality worldwide. Despite recognizing the importance of risk factors in dictating CVD susceptibility and onset, patient treatment remains a challenging endeavor. Increasingly, the benefits of prevention and mitigation of risk factors earlier in life are being acknowledged. The developmental origins of health and disease posits that insults during specific periods of development can influence long-term health outcomes; this occurs because the developing organism is highly plastic, and hence vulnerable to environmental perturbations. By extension, targeted therapeutics instituted during critical periods of development may confer long-term protection, and thus reduce the risk of CVD in later life. This review provides a brief overview of models of developmental programming, and then discusses the impact of perinatal therapeutic interventions on long-term cardiovascular function in the offspring. The discussion focuses on bioactive food components, as well as pharmacological agents currently approved for use in pregnancy; in short, those agents most likely to be used in pregnancy and early childhood.

Gestational Hypoxia and Developmental Plasticity

Hypoxia is one of the most common and severe challenges to the maintenance of homeostasis. Oxygen sensing is a property of all tissues, and the response to hypoxia is multidimensional involving complicated intracellular networks concerned with the transduction of hypoxia-induced responses. Of all the stresses to which the fetus and newborn infant are subjected, perhaps the most important and clinically relevant is that of hypoxia. Hypoxia during gestation impacts both the mother and fetal development through interactions with an individual's genetic traits acquired over multiple generations by natural selection and changes in gene expression patterns by altering the epigenetic code. Changes in the epigenome determine "genomic plasticity," i.e., the ability of genes to be differentially expressed according to environmental cues. The genomic plasticity defined by epigenomic mechanisms including DNA methylation, histone modifications, and noncoding RNAs during development is the mechanistic substrate for phenotypic programming that determines physiological response and risk for healthy or deleterious outcomes. This review explores the impact of gestational hypoxia on maternal health and fetal development, and epigenetic mechanisms of developmental plasticity with emphasis on the uteroplacental circulation, heart development, cerebral circulation, pulmonary development, and the hypothalamic-pituitary-adrenal axis and adipose tissue. The complex molecular and epigenetic interactions that may impact an individual's physiology and developmental programming of health and disease later in life are discussed.

Near to One's Heart: The Intimate Relationship Between the Placenta and Fetal Heart

The development of the fetal heart is exquisitely controlled by a multitude of factors, ranging from humoral to mechanical forces. The gatekeeper regulating many of these factors is the placenta, an external fetal organ. As such, resistance within the placental vascular bed has a direct influence on the fetal circulation and therefore, the developing heart. In addition, the placenta serves as the interface between the mother and fetus, controlling substrate exchange and release of hormones into both circulations. The intricate relationship between the placenta and fetal heart is appreciated in instances of clinical placental pathology. Abnormal umbilical cord insertion is associated with congenital heart defects. Likewise, twin-to-twin transfusion syndrome, where monochorionic twins have unequal sharing of their placenta due to inter-twin vascular anastomoses, can result in cardiac remodeling and dysfunction in both fetuses. Moreover, epidemiological studies have suggested a link between placental phenotypic traits and increased risk of cardiovascular disease in adult life. To date, the mechanistic basis of the relationships between the placenta, fetal heart development and later risk of cardiac dysfunction have not been fully elucidated. However, studies using environmental exposures and gene manipulations in experimental animals are providing insights into the pathways involved. Likewise, surgical instrumentation of the maternal and fetal circulations in large animal species has enabled the manipulation of specific humoral and mechanical factors to investigate their roles in fetal cardiac development. This review will focus on such studies and what is known to date about the link between the placenta and heart development.

Implication of Oxidative Stress in Fetal Programming of Cardiovascular Disease

Lifestyle and genetic background are well known risk factors of cardiovascular disease (CVD). A third contributing factor is suboptimal fetal development, due to nutrient or oxygen deprivation, placental insufficiency, or exposure to toxic substances. The fetus adapts to adverse intrauterine conditions to ensure survival; the immediate consequence is low birth weight (LBW) and the long-term effect is an increased susceptibility to develop CVD in adult life. This process is known as Developmental Origins of Health and Disease (DOHaD) or fetal programming of CVD. The influence of fetal life for the future cardiovascular health of the individual has been evidenced by numerous epidemiologic studies in populations suffering from starvation during intrauterine life. Furthermore, experimental animal models have provided support and enabled exploring the underlying mechanisms. Oxidative stress seems to play a central role in fetal programming of CVD, both in the response of the feto-placental unit to the suboptimal intrauterine environment and in the alterations of physiologic systems of cardiovascular control, ultimately leading to disease. This review aims to summarize current knowledge on the alterations in oxidative balance in response to fetal stress factors covering two aspects. Firstly, the evidence from human studies of the implication of oxidative stress in LBW induced by suboptimal conditions during intrauterine life, emphasizing the role of the placenta. In the second part we summarize data on specific redox alterations in key cardiovascular control organs induced by exposure to known stress factors in experimental animals and discuss the emerging role of the mitochondria.

Long-term cardiovascular consequences of fetal growth restriction: biology, clinical implications, and opportunities for prevention of adult disease

In the modern world, cardiovascular disease is a leading cause of death for both men and women. Epidemiologic studies consistently have suggested an association between low birthweight and/or fetal growth restriction and increased rate of cardiovascular mortality in adulthood. Furthermore, experimental and clinical studies have demonstrated that sustained nutrient and oxygen restriction that are associated with fetal growth restriction activate adaptive cardiovascular changes that might explain this association. Fetal growth restriction results in metabolic programming that may increase the risk of metabolic syndrome and, consequently, of cardiovascular morbidity in the adult. In addition, fetal growth restriction is strongly associated with fetal cardiac and arterial remodeling and a subclinical state of cardiovascular dysfunction. The cardiovascular effects ocurring in fetal life, includes cardiac morphology changes, subclinical myocardial dysfunction, arterial remodeling, and impaired endothelial function, persist into childhood and adolescence. Importantly, these changes have been described in all clinical presentations of fetal growth restriction, from severe early- to milder late-onset forms. In this review we summarize the current evidence on the cardiovascular effects of fetal growth restriction, from subcellular to organ structure and function as well as from fetal to early postnatal life. Future research needs to elucidate whether and how early life cardiovascular remodeling persists into adulthood and determines the increased cardiovascular mortality rate described in epidemiologic studies.

Gender-specific impairment of in vitro sinoatrial node chronotropic responses and of myocardial ischemia tolerance in rats exposed prenatally to betamethasone

Excessive fetal glucocorticoid exposure has been linked to increased susceptibility to hypertension and cardiac diseases in the adult life, a process called fetal programming. The cardiac contribution to the hypertensive phenotype of glucocorticoid-programmed progeny is less known, therefore, we investigated in vitro cardiac functional parameters from rats exposed in utero to betamethasone. Pregnant Wistar rats received vehicle (VEH) or betamethasone (BET, 0.1mg/kg, i.m.) at gestational days 12, 13, 18 and 19. Male and female offspring were killed at post-natal day 30 and the right atrium (RA) was isolated to in vitro evaluation of drug-induced chronotropic responses. Additionally, whole hearts were retrograde-perfused in a Langendorff apparatus and infarct size in response to in vitro ischemia/reperfusion (I/R) protocol was evaluated. Male and female progeny from BET-exposed pregnant rats had reduced birth weight, a hallmark of fetal programming. Male BET-progeny had increased basal RA rate, impaired chronotropic responses to noradrenaline and adenosine, and increased myocardial damage to I/R. Though a 12-fold reduction in the negative chronotropic responses to adenosine, the effects of non-metabolisable adenosine receptor agonists 5'-(N-ethylcarboxamido)adenosine or 2-Chloro-adenosine were not different between VEH- and BET-exposed male rats. BET-exposed female offspring presented no cardiac dysfunction. Prenatal BET exposure engenders male-specific impairment of sinoatrial node function and on myocardial ischemia tolerance resulting, at least in part, from an increased adenosine metabolism in the heart. In light of the importance of adenosine in the cardiac physiology our results suggest a link between reduced adenosinergic signaling and the cardiac dysfunctions observed in glucocorticoid-induced fetal programming.

Preserved heart function after left ventricular pressure overload in adult mice subjected to neonatal cardiac hypoplasia

Intrauterine growth restriction in animal models reduces heart size and cardiomyocyte number at birth. Such incomplete cardiomyocyte endowment is believed to increase susceptibility toward cardiovascular disease in adulthood, a phenomenon referred to as developmental programming. We have previously described a mouse model of impaired myocardial development leading to a 25% reduction of cardiomyocyte number in neonates. This study investigated the response of these hypoplastic hearts to pressure overload in adulthood, applied by abdominal aortic constriction (AAC). Echocardiography revealed a similar hypertrophic response in hypoplastic hearts compared with controls over the first 2 weeks. Subsequently, control mice develop mild left ventricular (LV) dilation, wall thinning and contractile dysfunction 4 weeks after AAC, whereas hypoplastic hearts fully maintain LV dimensions, wall thickness and contractility. At the cellular level, controls exhibit increased cardiomyocyte cross-sectional area after 4 weeks pressure overload compared with sham operated animals, but this hypertrophic response is markedly attenuated in hypoplastic hearts. AAC mediated induction of fibrosis, apoptosis or cell cycle activity was not different between groups. Expression of fetal genes, indicative of pathological conditions, was similar in hypoplastic and control hearts after AAC. Among various signaling pathways involved in cardiac hypertrophy, pressure overload induces p38 MAP-kinase activity in hypoplastic hearts but not controls compared with the respective sham operated animals. In summary, based on the mouse model used in this study, our data indicates that adult hearts after neonatal cardiac hypoplasia show an altered growth response to pressure overload, eventually resulting in better functional outcome compared with controls.

Maternal low-protein diet in female rat heart: possible protective effect of estradiol

Several studies have shown that maternal low-protein (LP) diet induces detrimental effects in cardiovascular system and oxidative stress in male animals. Additional studies suggested that female has lower incidence of cardiovascular disease. However until present data, the possible effects of estradiol on the undernutrition during gestational and lactation periods are not discussed. The present study was conducted to evaluate the effects of a maternal LP diet during gestational and lactation period on oxidative balance in the female rat hearts ventricles at two ages. Dams were fed with normal protein (NP) or a LP diet during the gestational and lactation period, and their female offspring were divided into age groups (22 or 122 days, corresponding to a low or high estrogen level) composing four experimental groups. Evaluating the nutritional effect showed an increase in oxidative stress biomarkers and decrease in enzymatic defense in LP-22D compared with NP-22D. In contrast, no changes were observed in malondialdehyde and carbonyls, but an increase in glutathione-S-transferase (GST) activity in the LP-122D compared with NP-122D. The global oxy-score in the LP-22D group indicated a predominance of oxidative damage when compared with NP-22D, while in LP-122D group the global oxy-score was restored to NP-122D levels. Evaluating the estradiol effect, our data show a significant decrease in oxidative stress with increase in CAT and GST activity, associated with increase in intracellular thiols. Our data suggest that in situation with low levels of estradiol, hypoproteic diet during gestation and lactation period has detrimental effects on heart, however when estradiol levels raise, the detrimental effects induced are mitigated.

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.

Neonatal Lipopolysaccharide Exposure Gender-Dependently Increases Heart Susceptibility to Ischemia/Reperfusion Injury in Male Rats

Background: Adverse stress exposure during the early neonatal period has been shown to cause aberrant development, resulting in an increased risk of adult disease. We tested the hypothesis that neonatal exposure to lipopolysaccharide (LPS) does not alter heart function at rest condition but causes heart dysfunction under stress stimulation later in life. Methods: Saline control or LPS were administered to neonatal rats via intraperitoneal injection. Experiments were conducted in 6 week-old male and female rats. Isolated hearts were perfused in a Langendorff preparation. Results: Neonatal LPS exposure exhibited no effects on the body weight of the developing rats, but induced decreases in the left ventricle (LV) to the body weight ratio in male rats. Neonatal LPS exposure showed no effects on the baseline heart function determined by in vivo and ex vivo experiments, but caused decreases in the post-ischemic recovery of the LV function in male but not female rats. Neonatal LPS-mediated LV dysfunction was associated with an increase in myocardial infarct size and the LDH release in the male rats. Conclusion: The present study provides novel evidence that neonatal immune challenges could induce gender-dependent long-term effects on cardiac development and heart function, which reinforces the notion that adverse stress exposure during the early neonatal period can aggravate heart functions and the development of a heart ischemia-sensitive phenotype later in life.

Ischemia/Reperfusion

Ischemic disorders, such as myocardial infarction, stroke, and peripheral vascular disease, are the most common causes of debilitating disease and death in westernized cultures. The extent of tissue injury relates directly to the extent of blood flow reduction and to the length of the ischemic period, which influence the levels to which cellular ATP and intracellular pH are reduced. By impairing ATPase-dependent ion transport, ischemia causes intracellular and mitochondrial calcium levels to increase (calcium overload). Cell volume regulatory mechanisms are also disrupted by the lack of ATP, which can induce lysis of organelle and plasma membranes. Reperfusion, although required to salvage oxygen-starved tissues, produces paradoxical tissue responses that fuel the production of reactive oxygen species (oxygen paradox), sequestration of proinflammatory immunocytes in ischemic tissues, endoplasmic reticulum stress, and development of postischemic capillary no-reflow, which amplify tissue injury. These pathologic events culminate in opening of mitochondrial permeability transition pores as a common end-effector of ischemia/reperfusion (I/R)-induced cell lysis and death. Emerging concepts include the influence of the intestinal microbiome, fetal programming, epigenetic changes, and microparticles in the pathogenesis of I/R. The overall goal of this review is to describe these and other mechanisms that contribute to I/R injury. Because so many different deleterious events participate in I/R, it is clear that therapeutic approaches will be effective only when multiple pathologic processes are targeted. In addition, the translational significance of I/R research will be enhanced by much wider use of animal models that incorporate the complicating effects of risk factors for cardiovascular disease. © 2017 American Physiological Society. Compr Physiol 7:113-170, 2017.

Early nutrition, epigenetics, and cardiovascular disease

PURPOSE OF REVIEW

Here, we provide a summary of the current knowledge on the impact of early life nutrition on cardiovascular diseases that have emerged from studies in humans and experimental animal models. The involvement of epigenetic mechanisms in the Developmental Origins of Health and Disease will be discussed in relation to the implications for the heart and the cardiovascular system.

RECENT FINDINGS

Environmental cues, such as parental diet and a suboptimal in utero environment can shape growth and development, causing long-lasting cardiometabolic perturbations. Increasing evidence suggest that these effects are mediated at the epigenomic level, and can be passed onto future generations. In the last decade, epigenetic mechanisms (DNA methylation, histone modifications) and RNA-based mechanisms (microRNAs, piRNAs, and tRNAs) have therefore emerged as potential candidates for mediating inheritance of cardiometabolic diseases.

SUMMARY

The burden of obesity and associated cardiometabolic diseases is believed to arise through interaction between an individual's genetics and the environment. Moreover, the risk of developing poor cardiometabolic health in adulthood is defined by early life exposure to pathological cues and can be inherited by future generations, initiating a vicious cycle of transmission of disease. Elucidating the molecular triggers of such a process will help tackle and prevent the uncontrolled rise in obesity and cardiometabolic disease.

Maternal inflammation activated ROS-p38 MAPK predisposes offspring to heart damages caused by isoproterenol via augmenting ROS generation

Maternal inflammation contributes to the increased incidence of adult cardiovascular disease. The current study investigated the susceptibility of cardiac damage responding to isoproterenol (ISO) in adult offspring that underwent maternal inflammation (modeled by pregnant Sprague-Dawley rats with lipopolysaccharides (LPS) challenge). We found that 2 weeks of ISO treatment in adult offspring of LPS-treated mothers led to augmented heart damage, characterized by left-ventricular systolic dysfunction, cardiac hypertrophy and myocardial fibrosis. Mechanistically, prenatal exposure to LPS led to up-regulated expression of nicotinamide adenine dinucleotide phosphate (NADPH) oxidases, antioxidant enzymes, and p38 MAPK activity in left ventricular of adult offspring at resting state. ISO treatment exaggerated ROS generation, p38 MAPK activation but down-regulated reactive oxygen species (ROS) elimination capacity in the left ventricular of offspring from LPS-treated mothers, while antioxidant N-acetyl-L-cysteine (NAC) reversed these changes together with improved cardiac functions. The p38 inhibitor SB202190 alleviated the heart damage only via inhibiting the expression of NADPH oxidases. Collectively, our data demonstrated that prenatal inflammation programs pre-existed ROS activation in the heart tissue, which switches on the early process of oxidative damages on heart rapidly through a ROS-p38 MAPK-NADPH oxidase-ROS positive feedback loop in response to a myocardial hypertrophic challenge in adulthood.

Effects of neonatal dexamethasone administration on cardiac recovery ability under ischemia-reperfusion in 24-wk-old rats

BACKGROUND

Evaluations of stress-induced cardiac functional alterations in adults after neonatal glucocorticoid (GC) treatment have been limited. In the present study, we evaluated adult cardiac functional recovery during postischemic reperfusion and measured cardiac gene expression involved energy metabolism in rats neonatally treated with dexamethasone (DEX).

METHOD

Male Wistar rats were injected DEX in first 3 d after birth and controls were received saline (SAL). At 24 wk of age, insulin tolerance tests were performed, plasma lipid levels were measured, and left ventricular function and myocardial infarct size were evaluated. Expressions of genes involved in cardiac energy metabolism were measured by quantitative real-time polymerase chain reaction (PCR) and western blot.

RESULTS

In 24-wk-old rats, neonatal DEX administration caused dyslipidemia, impaired cardiac recovery function and increased size of infarction, decreased cardiac expression of glucose transporter 4(GLUT4), peroxisome proliferative-activated receptor gamma coactivator 1α (PGC-1α) and ratios of phospho-forkhead box O1/forkhead box O1 (p-FoxO1/FoxO1) and phospho AMP-activated protein kinase/AMP-activated protein kinase (p-AMPK/AMPK) but increased pyruvate dehydrogenase kinase isoenzyme 4 (PDK4) expression compared with controls.

CONCLUSION

Neonatal DEX administration impairs cardiac functional recovery during reperfusion following ischemia in 24-wk-old rats. Reduced cardiac glucose utilization may contribute to the long-term detrimental effects caused by neonatal DEX treatment.

Higher protein intake increases cardiac function parameters in healthy children: metabolic programming by infant nutrition-secondary analysis from a clinical trial

BACKGROUND

Protein intake may modulate cardiac structure and function in pathological conditions, but there is a lack of knowledge on potential effects in healthy infants.

METHODS

Secondary analysis of an ongoing randomized clinical trial comparing two groups of infants receiving a higher (HP) or lower (LP) protein content formula in the first year of life, and compared with an observational group of breastfed (BF) infants. Growth and dietary intake were assessed periodically from birth to 2 y. Insulin-like growth factor 1 (IGF-1) axis parameters were analyzed at 6 mo in a blood sample. At 2 y, cardiac mass and function were assessed by echocardiography.

RESULTS

HP infants (n = 50) showed a higher BMI z-score at 2 y compared with LP (n = 47) or BF (n = 44). Cardiac function parameters were increased in the HP group compared with the LP and were directly related to the protein intake during the first 6 mo of life. Moreover, there was an increase in free IGF-1 in the HP group at 6 mo.

CONCLUSION

A moderate increase in protein supply during the first year of life is associated with higher cardiac function parameters at 2 y. IGF-1 axis modifications may, at least in part, underlie these effects.

Perinatal programming of renal function

PURPOSE OF REVIEW

Perinatal programming of renal function reflects the epigenetic alteration of genetically determined development by environmental factors. These include intrauterine malnutrition, pre and postnatal overnutrition, glucocorticoids, and certain toxins such as smoking. This review aims to summarize the most important findings.

RECENT FINDINGS

Human studies may show an increased susceptibility toward the general prevalence of renal failure in already small for gestational age children and adolescents. In particular, glomerular diseases present with a more severe clinical course. Partially related, partially independently, arterial hypertension is found in this at-risk group. The findings can mostly be confirmed in animal models. Both intrauterine nutrient deprived and overfed rodents show a tendency toward developing glomerulosclerosis and other renal disorders. Animal studies attempt to imitate clinical conditions, however, there are difficulties in transferring the findings to the human setting. The reduction of nephron number, especially in intrauterine growth-restricted humans and animals, is one mechanism of perinatal programming in the kidneys. In addition, vascular and endocrine alterations are prevalent. The molecular changes behind these mechanisms include epigenetic changes such as DNA-methylation, microRNAs, and histone modifications.

SUMMARY

Future research will have to establish clinical studies with clear and well defined inclusion criteria which also reflect prenatal life. The use of transgenic animal models might help to obtain a deeper insight into the underlying mechanisms.

Early Programming by Protein Intake: The Effect of Protein on Adiposity Development and the Growth and Functionality of Vital Organs

This article reviews the role of protein intake on metabolic programming early in life. The observations that breastfeeding in infancy reduces the risk of being overweight and obese later in life and the differences in the protein content between formula milk and human milk have generated the early protein hypothesis. The present review focuses on a mechanistic approach to programmed adiposity and the growth and development of other organs by protein intake in infancy, which may be mediated by branched-chain amino acids, insulin, and insulin-like growth factor 1 via the mammalian target of rapamycin. Observational studies and clinical trials have shown that lowering the protein content in infant and follow-on formulas may reduce the risk of becoming obese later in life. The recent body of evidence is currently being translated into new policies. Therefore, the evolution of European regulatory laws and recommendations by expert panels on the protein content of infant and follow-on formulas are also reviewed. Research gaps, such as the critical window for programming adiposity by protein intake, testing formulas with modified amino acids, and the long-term consequences of differences in protein intake on organ functionality among well-nourished infants, have been identified.

The Programming Power of the Placenta

Size at birth is a critical determinant of life expectancy, and is dependent primarily on the placental supply of nutrients. However, the placenta is not just a passive organ for the materno-fetal transfer of nutrients and oxygen. Studies show that the placenta can adapt morphologically and functionally to optimize substrate supply, and thus fetal growth, under adverse intrauterine conditions. These adaptations help meet the fetal drive for growth, and their effectiveness will determine the amount and relative proportions of specific metabolic substrates supplied to the fetus at different stages of development. This flow of nutrients will ultimately program physiological systems at the gene, cell, tissue, organ, and system levels, and inadequacies can cause permanent structural and functional changes that lead to overt disease, particularly with increasing age. This review examines the environmental regulation of the placental phenotype with particular emphasis on the impact of maternal nutritional challenges and oxygen scarcity in mice, rats and guinea pigs. It also focuses on the effects of such conditions on fetal growth and the developmental programming of disease postnatally. A challenge for future research is to link placental structure and function with clinical phenotypes in the offspring.

Protective Effect of Antenatal Antioxidant on Nicotine-Induced Heart Ischemia-Sensitive Phenotype in Rat Offspring

Fetal nicotine exposure increased risk of developing cardiovascular disease later in life. The present study tested the hypothesis that perinatal nicotine-induced programming of heart ischemia-sensitive phenotype is mediated by enhanced reactive oxygen species (ROS) in offspring. Nicotine was administered to pregnant rats via subcutaneous osmotic minipumps from day 4 of gestation to day 10 after birth, in the absence or presence of a ROS inhibitor, N-acetyl-cysteine (NAC) in drinking water. Experiments were conducted in 8 month old age male offspring. Isolated hearts were perfused in a Langendorff preparation. Perinatal nicotine treatment significantly increased ischemia and reperfusion-induced left ventricular injury, and decreased post-ischemic recovery of left ventricular function and coronary flow rate. In addition, nicotine enhanced cardiac ROS production and significantly attenuated protein kinase Cε (PKCε) protein abundance in the heart. Although nicotine had no effect on total cardiac glycogen synthase kinase-3β (GSK3β) protein expression, it significantly increased the phosphorylation of GSK3β at serine 9 residue in the heart. NAC inhibited nicotine-mediated increase in ROS production, recovered PKCε gene expression and abrogated increased phosphorylation of GSK3β. Of importance, NAC blocked perinatal nicotine-induced increase in ischemia and reperfusion injury in the heart. These findings provide novel evidence that increased oxidative stress plays a causal role in perinatal nicotine-induced developmental programming of ischemic sensitive phenotype in the heart, and suggest potential therapeutic targets of anti-oxidative stress in the treatment of ischemic heart disease.

Maternal high-fat feeding in pregnancy programs atherosclerotic lesion size in the ApoE*3 Leiden mouse

Periods of rapid growth seen during the early stages of fetal development, including cell proliferation and differentiation, are greatly influenced by the maternal environment. We demonstrate here that over-nutrition, specifically exposure to a high-fat diet in utero, programed the extent of atherosclerosis in the offspring of ApoE*3 Leiden transgenic mice. Pregnant ApoE*3 Leiden mice were fed either a control chow diet (2.8% fat, n=12) or a high-fat, moderate-cholesterol diet (MHF, 19.4% fat, n=12). Dams were fed the chow diet during the suckling period. At 28 days postnatal age wild type and ApoE*3 Leiden offspring from chow or MHF-fed mothers were fed either a control chow diet (n=37) or a diet rich in cocoa butter (15%) and cholesterol (0.25%), for 14 weeks to induce atherosclerosis (n=36). Offspring from MHF-fed mothers had 1.9-fold larger atherosclerotic lesions (P<0.001). There was no direct effect of prenatal diet on plasma triglycerides or cholesterol; however, transgenic ApoE*3 Leiden offspring displayed raised cholesterol when on an atherogenic diet compared with wild-type controls (P=0.031). Lesion size was correlated with plasma lipid parameters after adjustment for genotype, maternal diet and postnatal diet (R 2=0.563, P<0.001). ApoE*3 Leiden mothers fed a MHF diet developed hypercholesterolemia (plasma cholesterol two-fold higher than in chow-fed mothers, P=0.011). The data strongly suggest that maternal hypercholesterolemia programs later susceptibility to atherosclerosis. This is consistent with previous observations in humans and animal models.

Maternal Low Quality Protein Diet Alters Plasma Amino Acid Concentrations of Weaning Rats

Several studies have indicated the influence of a maternal low protein diet on the fetus. However, the effect of a maternal low quality protein diet on fetal growth and development is largely unknown. Wistar rats (11 weeks old) were mated and maintained on either a chow diet with 20% casein (n = 6) as the control group (C), or a low quality protein diet with 20% wheat gluten (n = 7) as the experimental group (WG) through gestation and lactation. Maternal body weights were similar in both groups throughout the study. Birth weights were not influenced by maternal diet and offspring body weights during lactation were similar between the groups. Offspring’s plasma amino acid profiles showed that plasma methionine, glutamine and lysine were significantly lower and aspartic acid, ornithine and glycine-proline were significantly higher in the WG. Plant based protein comprises an important part of protein intake in developing countries. It is well-known that these diets can be inadequate in terms of essential amino acids. The current study shows differential effects of a maternal low quality protein diet on the offspring’s plasma amino acids. Future studies will examine further aspects of the influence of maternal low quality protein diets on fetal growth and development.

Maternal protein restriction increases respiratory and sympathetic activities and sensitizes peripheral chemoreflex in male rat offspring

BACKGROUND

Maternal protein restriction in rats increases the risk of adult offspring arterial hypertension through unknown mechanisms.

OBJECTIVES

The aims of the study were to evaluate the effects of a low-protein (LP) diet during pregnancy and lactation on baseline sympathetic and respiratory activities and peripheral chemoreflex sensitivity in the rat offspring.

METHODS

Wistar rat dams were fed a control [normal-protein (NP); 17% protein] or an LP (8% protein) diet during pregnancy and lactation, and their male offspring were studied at 30 d of age. Direct measurements of baseline arterial blood pressure (ABP), heart rate (HR), and respiratory frequency (Rf) as well as peripheral chemoreflex activation (potassium cyanide: 0.04%) were recorded in pups while they were awake. In addition, recordings of the phrenic nerve (PN) and thoracic sympathetic nerve (tSN) activities were obtained from the in situ preparations. Hypoxia-inducible factor 1α (HIF-1α) expression was also evaluated in carotid bifurcation through a Western blotting assay.

RESULTS

At 30 d of age, unanesthetized LP rats exhibited enhanced resting Rf (P = 0.001) and similar ABP and HR compared with the NP rats. Despite their similar baseline ABP values, LP rats exhibited augmented low-frequency variability (∼91%; P = 0.01). In addition, the unanesthetized LP rats showed enhanced pressor (P = 0.01) and tachypnoeic (P = 0.03) responses to peripheral chemoreflex activation. The LP rats displayed elevated baseline tSN activity (∼86%; P = 0.02) and PN burst frequency (45%; P = 0.01) and amplitude (53%; P = 0.001) as well as augmented sympathetic (P = 0.01) and phrenic (P = 0.04) excitatory responses to peripheral chemoreflex activation compared with the NP group. Furthermore, LP rats showed an increase of ∼100% in HIF-1α protein density in carotid bifurcation compared with NP rats.

CONCLUSION

Sympathetic-respiratory overactivity and amplified peripheral chemoreceptor responses, potentially through HIF-1α-dependent mechanisms, precede the onset of hypertension in juvenile rats exposed to protein undernutrition during gestation and lactation.

Increased systolic blood pressure in rat offspring following a maternal low-protein diet is normalized by maternal dietary choline supplementation

An adverse prenatal environment may induce long-term metabolic consequences, in particular hypertension and cardiovascular disease. A maternal low-protein (LP) diet is well known to result in increased blood pressure (BP) in offspring. Choline has been shown to have direct BP-reducing effects in humans and animals. It has been suggested that endogenous choline synthesis via phosphatidylcholine is constrained during maternal LP exposure. The present study investigates the effect of choline supplementation to mothers fed a LP diet during pregnancy on systolic BP (SBP) in offspring as measured by tail-cuff plethysmography. Wistar rats were assigned to one of three diets to be fed ad libitum throughout pregnancy: (1) control diet (CONT, 20% protein); (2) an LP diet (9% protein); and (3) LP supplemented with choline (LP + C). Dams were fed the CONT diet throughout lactation and offspring were fed the CONT diet from weaning for the remainder of the trial. At postnatal day 150, SBP and retroperitoneal fat mass was significantly increased in LP offspring compared with CONT animals and was normalized in LP + C offspring. Effects of LP + C reduction in SBP were similar in both males and females. Plasma choline and phosphatidylcholine concentrations were not different across treatment groups, but maternal choline supplementation resulted in a significant reduction in homocysteine concentrations in LP + C offspring compared with LP and CONT animals. The present trial shows for the first time that maternal supplementation with dietary choline during periods of LP exposure can normalize increased SBP and fat mass observed in offspring in later life.

Impaired myocardial development resulting in neonatal cardiac hypoplasia alters postnatal growth and stress response in the heart

AIMS

Foetal growth has been proposed to influence cardiovascular health in adulthood, a process referred to as foetal programming. Indeed, intrauterine growth restriction in animal models alters heart size and cardiomyocyte number in the perinatal period, yet the consequences for the adult or challenged heart are largely unknown. The aim of this study was to elucidate postnatal myocardial growth pattern, left ventricular function, and stress response in the adult heart after neonatal cardiac hypoplasia in mice.

METHODS AND RESULTS

Utilizing a new mouse model of impaired cardiac development leading to fully functional but hypoplastic hearts at birth, we show that myocardial mass is normalized until early adulthood by accelerated physiological cardiomyocyte hypertrophy. Compensatory hypertrophy, however, cannot be maintained upon ageing, resulting in reduced organ size without maladaptive myocardial remodelling. Angiotensin II stress revealed aberrant cardiomyocyte growth kinetics in adult hearts after neonatal hypoplasia compared with normally developed controls, characterized by reversible overshooting hypertrophy. This exaggerated growth mainly depends on STAT3, whose inhibition during angiotensin II treatment reduces left ventricular mass in both groups but causes contractile dysfunction in developmentally impaired hearts only. Whereas JAK/STAT3 inhibition reduces cardiomyocyte cross-sectional area in the latter, it prevents fibrosis in control hearts, indicating fundamentally different mechanisms of action.

CONCLUSION

Impaired prenatal development leading to neonatal cardiac hypoplasia alters postnatal cardiac growth and stress response in vivo, thereby linking foetal programming to organ size control in the heart.

Developmental programming of cardiovascular disease following intrauterine growth restriction: findings utilising a rat model of maternal protein restriction

Over recent years, studies have demonstrated links between risk of cardiovascular disease in adulthood and adverse events that occurred very early in life during fetal development. The concept that there are embryonic and fetal adaptive responses to a sub-optimal intrauterine environment often brought about by poor maternal diet that result in permanent adverse consequences to life-long health is consistent with the definition of "programming". The purpose of this review is to provide an overview of the current knowledge of the effects of intrauterine growth restriction (IUGR) on long-term cardiac structure and function, with particular emphasis on the effects of maternal protein restriction. Much of our recent knowledge has been derived from animal models. We review the current literature of one of the most commonly used models of IUGR (maternal protein restriction in rats), in relation to birth weight and postnatal growth, blood pressure and cardiac structure and function. In doing so, we highlight the complexity of developmental programming, with regards to timing, degree of severity of the insult, genotype and the subsequent postnatal phenotype.

Early developmental conditioning of later health and disease: physiology or pathophysiology?

Extensive experimental animal studies and epidemiological observations have shown that environmental influences during early development affect the risk of later pathophysiological processes associated with chronic, especially noncommunicable, disease (NCD). This field is recognized as the developmental origins of health and disease (DOHaD). We discuss the extent to which DOHaD represents the result of the physiological processes of developmental plasticity, which may have potential adverse consequences in terms of NCD risk later, or whether it is the manifestation of pathophysiological processes acting in early life but only becoming apparent as disease later. We argue that the evidence suggests the former, through the operation of conditioning processes induced across the normal range of developmental environments, and we summarize current knowledge of the physiological processes involved. The adaptive pathway to later risk accords with current concepts in evolutionary developmental biology, especially those concerning parental effects. Outside the normal range, effects on development can result in nonadaptive processes, and we review their underlying mechanisms and consequences. New concepts concerning the underlying epigenetic and other mechanisms involved in both disruptive and nondisruptive pathways to disease are reviewed, including the evidence for transgenerational passage of risk from both maternal and paternal lines. These concepts have wider implications for understanding the causes and possible prevention of NCDs such as type 2 diabetes and cardiovascular disease, for broader social policy and for the increasing attention paid in public health to the lifecourse approach to NCD prevention.

Feeding a protein-restricted diet during pregnancy induces altered epigenetic regulation of peroxisomal proliferator-activated receptor-α in the heart of the offspring

Impaired flexibility in the use of substrates for energy production in the heart is implicated in cardiomyopathy. We investigated the effect of maternal protein restriction during pregnancy in rats on the transcription of key genes in cardiac lipid and carbohydrate metabolism in the offspring. Rats were fed protein-sufficient or protein-restricted (PR) diets during pregnancy. Triacylglycerol concentration in adult (day 105) heart was altered by maternal protein intake contingent on post-weaning fat intake and sex. mRNA expression of peroxisomal proliferator-activated receptor (PPAR)-α and carnitine palmitoyltransferase-1 was increased by the maternal PR diet in adult, but not neonatal, offspring. PPARα promoter methylation was lower in adult and neonatal heart from PR offspring. These findings suggest that prenatal nutrition alters the future transcriptional regulation of cardiac energy metabolism in the offspring through changes in epigenetic regulation of specific genes. However, changes in gene functional changes may not be apparent in early life.

When early life growth restriction in rats is followed by attenuated postnatal growth: effects on cardiac function in adulthood

PURPOSE

Epidemiological and experimental studies demonstrate that intrauterine growth restriction (IUGR) followed by accelerated postnatal growth leads to increased risk of developing cardiac disease in adulthood. The aim of this study was to examine the effect of early life growth restriction on cardiac structure and function in young adult rats.

METHODS

IUGR was induced in Wistar Kyoto dams through administration of a low protein diet (LPD; 8.7% casein) during pregnancy and lactation; controls received a normal protein diet (NPD; 20% casein). Cardiac function and structure were assessed in female NPD (n = 7) and LPD (n = 7) offspring at 18 weeks of age by echocardiography and pressure-volume techniques, and systolic blood pressure by tail-cuff sphygmomanometry.

RESULTS

LPD offspring remained significantly smaller throughout life compared to controls. There were no differences in the levels of systolic blood pressure, left ventricular cardiac dimensions, heart rate, ejection fraction and fractional shortening of the cardiac muscle between the investigated groups. Aortic peak systolic velocity was significantly reduced in the LPD group (P = 0.02).

CONCLUSION

Our findings support the idea that the programming of adult cardiovascular disease can be prevented or delayed in IUGR offspring when postnatal growth trajectory resembles that of in utero.

The regulation of pre- and post-maturational plasticity of mammalian islet cell mass

Regeneration of mature cells that produce functional insulin represents a major focus and a challenge of current diabetes research aimed at restoring beta cell mass in patients with most forms of diabetes, as well as in ageing. The capacity to adapt to diverse physiological states during life and the consequent ability to cope with increased metabolic demands in the normal regulation of glucose homeostasis is a distinctive feature of the endocrine pancreas in mammals. Both beta and alpha cells, and presumably other islet cells, are dynamically regulated via nutrient, neural and/or hormonal activation of growth factor signalling and the post-transcriptional modification of a variety of genes or via the microbiome to continually maintain a balance between regeneration (e.g. proliferation, neogenesis) and apoptosis. Here we review key regulators that determine islet cell mass at different ages in mammals. Understanding the chronobiology and the dynamics and age-dependent processes that regulate the relationship between the different cell types in the overall maintenance of an optimally functional islet cell mass could provide important insights into planning therapeutic approaches to counter and/or prevent the development of diabetes.

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.

The impact of early nutrition on the ageing trajectory

Epidemiological studies, including those in identical twins, and in individuals in utero during periods of famine have provided robust evidence of strong correlations between low birth-weight and subsequent risk of disease in later life, including type 2 diabetes (T2D), CVD, and metabolic syndrome. These and studies in animal models have suggested that the early environment, especially early nutrition, plays an important role in mediating these associations. The concept of early life programming is therefore widely accepted; however the molecular mechanisms by which early environmental insults can have long-term effects on a cell and consequently the metabolism of an organism in later life, are relatively unclear. So far, these mechanisms include permanent structural changes to the organ caused by suboptimal levels of an important factor during a critical developmental period, changes in gene expression caused by epigenetic modifications (including DNA methylation, histone modification and microRNA) and permanent changes in cellular ageing. Many of the conditions associated with early-life nutrition are also those which have an age-associated aetiology. Recently, a common molecular mechanism in animal models of developmental programming and epidemiological studies has been development of oxidative stress and macromolecule damage, specifically DNA damage and telomere shortening. These are phenotypes common to accelerated cellular ageing. Thus, this review will encompass epidemiological and animal models of developmental programming with specific emphasis on cellular ageing and how these could lead to potential therapeutic interventions and strategies which could combat the burden of common age-associated disease, such as T2D and CVD.

The fetal origins of hypertension: a systematic review and meta-analysis of the evidence from animal experiments of maternal undernutrition

OBJECTIVE

Numerous experiments in animals have been performed to investigate the effect of prenatal undernutrition on the development of hypertension in later life, with inconclusive results. We systematically reviewed animal studies examining the effects of maternal undernutrition on SBP, DBP, and mean arterial blood pressure (BP) in offspring.

METHODS

A search was performed in Medline and Embase to identify articles that reported on maternal undernutrition and hypertension in experimental animal studies. Summary estimates of the effect of undernutrition on SBP, DBP, and mean arterial BP were obtained through meta-analysis.

RESULTS

Of the 6151 articles identified, 194 were considered eligible after screening titles and abstracts. After detailed evaluation, 101 met the inclusion criteria and were included in the review. Both maternal general and protein undernutrition increased SBP [general undernutrition: 14.5 mmHg, 95% confidence interval (CI) 10.8-18.3; protein undernutrition: 18.9 mmHg, 95% CI 16.1-21.8] and mean arterial BP (general undernutrition: 5.0 mmHg, 95% CI 1.4-8.6; protein undernutrition: 10.5 mmHg, 95% CI 6.7-14.2). There was substantial heterogeneity in the results. DBP was increased by protein undernutrition (9.5 mmHg, 95% CI 2.6-16.3), whereas general undernutrition had no significant effect.

CONCLUSION

The results of this meta-analysis generally support the view that in animals, maternal undernutrition--both general and protein--results in increased SBP and mean arterial BP. DBP was only increased after protein undernutrition. The results depended strongly on the applied measurement technique and animal model.

Growth restriction in the rat alters expression of metabolic genes during postnatal cardiac development in a sex-specific manner

This study investigated the impact of uteroplacental insufficiency and growth restriction on the expression of genes related to mitochondrial biogenesis, glucose transport, and antioxidant defenses in cardiac tissue at embryonic day 20 (E20) and postnatal days 1, 7, and 35 in male and female Wistar rats (8-10 per group). Bilateral uterine vessel ligation to induce growth restriction (Restricted) or sham surgery was performed at pregnancy day 18. In male and female Controls, expression of most cardiac genes decreased during postnatal life, including genes involved in mitochondrial biogenesis regulation such as PGC-1α, NRF-2, and mtTFA and the glucose transporter GLUT-1 (P < 0.05). However, the pattern of gene expression during cardiac development differed in male and female Restricted rats compared with their respective Controls. These effects of restriction were observed at postnatal day 1, with female Restricted rats having delayed reductions in PGC-1α and GLUT-1, whereas males had exacerbated reductions in PGC-1α and mtTFA (P < 0.05). By day 35, cardiac gene expression in Restricted hearts was similar to Controls, except for expression of the antioxidant enzyme MnSOD, which was significantly lower in both sexes. In summary, during postnatal life male and female Control rats have similar patterns of expression for genes involved in mitochondrial biogenesis and glucose transport. However, following uteroplacental insufficiency these gene expression patterns diverge in males and females during early postnatal life, with MnSOD gene expression reduced in later postnatal life.

Developmental origins of health and adult disease: what should neonatologists/paediatricians be considering about the long-term health of their patients?

The developmental origins of health and disease hypothesis is now strongly supported by both animal and human evidence, and as a consequence, obstetricians, neonatologists and paediatricians need to consider the impact that the in utero and early post-natal environment can have on later renal, cardiovascular and metabolic health. Four common clinical scenarios were provided along with animal and human evidence identifying long-term health implications. Suggestions as to how we should translate this growing body of evidence into practice are provided.

Impact of oxidative stress in fetal programming

Intrauterine stress induces increased risk of adult disease through fetal programming mechanisms. Oxidative stress can be generated by several conditions, such as, prenatal hypoxia, maternal under- and overnutrition, and excessive glucocorticoid exposure. The role of oxidant molecules as signaling factors in fetal programming via epigenetic mechanisms is discussed. By linking oxidative stress with dysregulation of specific target genes, we may be able to develop therapeutic strategies that protect against organ dysfunction in the programmed offspring.

Effects of hypoxia-induced intrauterine growth restriction on cardiac siderosis and oxidative stress

We have previously shown that adult rat offspring born intrauterine growth restricted (IUGR) as a result of a prenatal hypoxic insult exhibit several cardiovascular characteristics that are compatible with common manifestations of chronic iron toxicity. As hypoxia is one of the major regulators of iron absorption and metabolism, we hypothesized that hypoxia-induced IUGR offspring will have long-term changes in their ability to regulate iron metabolism leading to myocardial iron deposition and induction of myocardial oxidative stress. Pregnant Sprague Dawley rats were randomized to control (n = 8) or maternal hypoxia (11.5% oxygen; n = 8) during the last 6 days of pregnancy. At birth, litters were reduced to eight pups (four male and four female). At 4 or 12 months of age, offspring were euthanatized and samples (blood and myocardium) were collected. In only the male offspring, IUGR and aging were associated with an increase in myocardial markers of oxidative stress such as oxidized/reduced glutathione ratio and malondialdehyde. Aged male IUGR offspring also exhibited interstitial myocardial remodeling characterized by myocyte loss and disrupted extracellular matrix.Contrary to our hypothesis, however, neither IUGR nor aging were associated with changes in any systemic or local markers of iron metabolism. Our results suggest that hypoxic insults leading to IUGR produce long-term effects on the levels of oxidative stress and connective tissue distribution in the myocardium of male but not female offspring.

Fetal programming of renal function

Results from large epidemiological studies suggest a clear relation between low birth weight and adverse renal outcome evident as early as during childhood. Such adverse outcomes may include glomerular disease, hypertension, and renal failure and contribute to a phenomenon called fetal programming. Other factors potentially leading to an adverse renal outcome following fetal programming are maternal diabetes mellitus, smoking, salt overload, and use of glucocorticoids during pregnancy. However, clinical data on the latter are scarce. Here, we discuss potential underlying mechanisms of fetal programming, including reduced nephron number via diminished nephrogenesis and other renal (e.g., via the intrarenal renin-angiotensin-aldosterone system) and non-renal (e.g., changes in endothelial function) alterations. It appears likely that the outcomes of fetal programming may be influenced or modified postnatally, for example, by the amount of nutrients given at critical times.

The Effects of Prenatal Protein Restriction on β-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 β₂-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 β₂-AR and reduced noradrenaline and dopamine levels. In contrast, females exhibiting both decreased membrane expression of β₂-AR and catecholamine levels were protected from IR injury.

Maternal periconceptional and gestational low protein diet affects mouse offspring growth, cardiovascular and adipose phenotype at 1 year of age

Human and animal studies have revealed a strong association between periconceptional environmental factors, such as poor maternal diet, and an increased propensity for cardiovascular and metabolic disease in adult offspring. Previously, we reported cardiovascular and physiological effects of maternal low protein diet (LPD) fed during discrete periods of periconceptional development on 6-month-old mouse offspring. Here, we extend the analysis in 1 year aging offspring, evaluating mechanisms regulating growth and adiposity. Isocaloric LPD (9% casein) or normal protein diet (18% casein; NPD) was fed to female MF-1 mice either exclusively during oocyte maturation (for 3.5 days prior to mating; Egg-LPD, Egg-NPD, respectively), throughout gestation (LPD, NPD) or exclusively during preimplantation development (for 3.5 days post mating; Emb-LPD). LPD and Emb-LPD female offspring were significantly lighter and heavier than NPD females respectively for up to 52 weeks. Egg-LPD, LPD and Emb-LPD offspring displayed significantly elevated systolic blood pressure at 52 weeks compared to respective controls (Egg-NPD, NPD). LPD females had significantly reduced inguinal and retroperitoneal fat pad: body weight ratios compared to NPD females. Expression of the insulin receptor (Insr) and insulin-like growth factor I receptor (Igf1r) in retroperitoneal fat was significantly elevated in Emb-LPD females (P<0.05), whilst Emb-LPD males displayed significantly decreased expression of the mitochondrial uncoupling protein 1 (Ucp1) gene compared to NPD offspring. LPD females displayed significantly increased expression of Ucp1 in interscapular brown adipose tissue when compared to NPD offspring. Our results demonstrate that aging offspring body weight, cardiovascular and adiposity homeostasis can be programmed by maternal periconceptional nutrition. These adverse outcomes further exemplify the criticality of dietary behaviour around the time of conception on long-term offspring health.

Increased cardiovascular reactivity to acute stress and salt-loading in adult male offspring of fat fed non-obese rats

Diet-induced obesity in rat pregnancy has been shown previously to be associated with consistently raised blood pressure in the offspring, attributed to sympathetic over-activation, but the relative contributions to this phenotype of maternal obesity versus raised dietary fat is unknown. Sprague-Dawley female rats were fed either a control (4.3% fat, n = 11) or lard-enriched (23.6% fat, n = 16) chow 10 days prior to mating, throughout pregnancy and lactation. In conscious adult (9-month-old) offspring cardiovascular parameters were measured (radiotelemetry). The short period of fat-feeding did not increase maternal weight versus controls and the baseline blood pressure was similar in offspring of fat fed dams (OF) and controls (OC). However, adult male OF showed heightened cardiovascular reactivity to acute restraint stress (p<0.01; Δ systolic blood pressure (SBP) and Δheart rate (HR)) with a prolonged recovery time compared to male OC. α1/β-adrenergic receptor blockade normalised the response. Also, after dietary salt-loading (8%-NaCl ad libitum for 1 week) male OF demonstrated higher SBP (p<0.05) in the awake phase (night-time) and increased low/high frequency ratio of power spectral density of HR variability versus OC. Baroreflex gain and basal power spectral density components of the heart rate or blood pressure were similar in male OF and OC. Minor abnormalities were evident in female OF. Fat feeding in the absence of maternal obesity in pregnant rats leads to altered sympathetic control of cardiovascular function in adult male offspring, and hypertension in response to stressor stimuli.

Low birth weight, bone metabolism and fracture risk

As for other diseases of higher age, low birth weight was expected to be a risk factor for an altered bone metabolism and osteoporosis.ON THE FIRST GLANCE THIS EXPECTATION APPEARS TO BE CONFIRMED BY ANIMAL DATA: rats with intrauterine growth restriction following maternal protein malnutrition show a reduction of bone mineral density going in line with a decrease in serum vitamin D concentrations.HOWEVER, THE SITUATION IS LESS CLEAR IN NEWBORNS WITH LOW BIRTH WEIGHT: Some studies show a relation of birth weight and bone mineral density whereas others don't. The older the former low birth weight patients the fainter the effect seems to be. In fact young adults with idiopathic short stature have a low bone mineral density than the low birth weight group irrespective of whether they have experienced catch-up growth or not. As a consequence low birth weight is can not be identified as a relevant risk factor for hip fractures in menopausal women. Postmenopausal women with low birth weight even show higher vitamin D concentrations than normal birth weight individuals.In conclusion, there is no consistent long term effect of low birth weight on bone mineral density or hip fracture risk later in life. Whether methodological weaknesses in the studies performed so far are causal or whether postnatal factors such as physical activity and nutrition are of higher importance can only be speculated upon at present.

Nutritional programming of pancreatic β-cell plasticity

Nutritional insufficiency during pregnancy has been shown to alter the metabolism of the offspring and can increase the risk of type 2 diabetes. The phenotype in the offspring involves changes to the morphology and functional capacity of the endocrine pancreas, and in the supporting islet microvasculature. Pancreatic β-cells possess a plastic potential and can partially recover from catastrophic loss. This is partly due to the existence of progenitors within the islets and the ability to generate new islets by neogenesis from the pancreatic ducts. This regenerative capacity is induced by bone marrow-derived stem cells, including endothelial cell progenitors and is associated with increased angiogenesis within the islets. Nutritional insults in early life, such as feeding a low protein diet to the mother, impair the regenerative capacity of the β-cells. The mechanisms underlying this include a reduced ability of β-cells to differentiate from the progenitor population, changes in the inductive signals from the microvasculature and an altered presence of endothelial progenitors. Statin treatment within animal models was associated with angiogenesis in the islet microvasculature, improved vascular function and an increase in β-cell mass. This demonstrates that reversal of the impaired β-cell phenotype observed following nutritional insult in early life is potentially possible.

Cultured neonatal rat cardiomyocytes display differences in glucose uptake and sensitivity to dexamethasone related to maternal diet

Feeding a low protein (LP) diet in rat pregnancy is associated with impaired cardiovascular health and function, possibly as a result of tissue remodelling. To assess whether cardiomyocytes retain differences induced by protein restriction, cells from neonatal rats exposed to control or LP diets in utero were cultured for a period of 10 days. At the end of this period, no differences in cell size, proliferation differentiation or metabolic function were noted. When treated with dexamethasone (0.1-10 μM) for 2 days, it was noted that insulin-stimulated glucose uptake was enhanced, but only in cells from LP rats. Increased glucocorticoid sensitivity of cardiomyocytes from LP rats could not be explained by differential expression of the glucocorticoid receptor or the glucose transporters, GLUT1 and GLUT4. The findings of the study suggest that sensitivity to endocrine signals may be permanently programmed by undernutrition through mechanisms that are preserved in vitro.

Programming of adult cardiovascular disease following exposure to late-gestation hyperglycemia

BACKGROUND

In utero exposure to hyperglycemia is becoming increasingly prevalent as the number of women entering pregnancy with type II diabetes, or developing gestational diabetes, increases. Both animal studies and epidemiologic investigations have found cardiovascular abnormalities in adult offspring of hyperglycemic mothers (OHM).

OBJECTIVE

We hypothesized that adult OHM would have abnormal cardiac function in vivo and increased susceptibility to ischemia.

METHODS

Pregnant rats were made diabetic on day 12 of gestation. Serum glucose was monitored twice daily and insulin provided to maintain serum glucose at 200-400 mg/dl. Offspring were fostered to normal mothers after birth. Adult OHM were studied at 8-10 months of age with echocardiography to assess in vivo cardiac function and isolated hearts to determine the response to ischemia.

RESULTS

Echocardiography found significant diastolic dysfunction in male OHM compared to male controls. In isolated hearts, baseline cardiac function and left ventricular compliance was significantly diminished in male OHM compared to controls. Ischemia caused a significant decline in heart function in controls and female OHM, while function in male OHM remained unchanged.

CONCLUSIONS

Adult male OHM demonstrate programmed cardiac dysfunction. Given the growing number of pregnancies complicated by hyperglycemia, additional assessment of cardiac function of adults born to diabetic mothers may be warranted.