Normal Lactational Environment Restores Nephron Endowment and Prevents Hypertension after Placental Restriction in the Rat

Endurance training in early life results in long-term programming of heart mass in rats

Being born small for gestational age increases the risk of developing adult cardiovascular and metabolic diseases. This study aimed to examine if early‐life exercise could increase heart mass in the adult hearts from growth restricted rats. Bilateral uterine vessel ligation to induce uteroplacental insufficiency and fetal growth restriction in the offspring (Restricted) or sham surgery (Control) was performed on day 18 of gestation in WKY rats. A separate group of sham litters had litter size reduced to five pups at birth (Reduced litter), which restricted postnatal growth. Male offspring remained sedentary or underwent treadmill running from 5 to 9 weeks (early exercise) or 20 to 24 weeks of age (later exercise). Remarkably, in Control, Restricted, and Reduced litter groups, early exercise increased (P < 0.05) absolute and relative (to body mass) heart mass in adulthood. This was despite the animals being sedentary for ~4 months after exercise. Later exercise also increased adult absolute and relative heart mass (P < 0.05). Blood pressure was not significantly altered between groups or by early or later exercise. Phosphorylation of Akt Ser⁴⁷³ in adulthood was increased in the early exercise groups but not the later exercise groups. Microarray gene analysis and validation by real‐time PCR did not reveal any long‐term effects of early exercise on the expression of any individual genes. In summary, early exercise programs the heart for increased mass into adulthood, perhaps by an upregulation of protein synthesis based on greater phosphorylation of Akt Ser⁴⁷³.

Intrauterine growth restriction programs an accelerated age-related increase in cardiovascular risk in male offspring

Placental insufficiency programs an increase in blood pressure associated with a twofold increase in serum testosterone in male growth-restricted offspring at 4 mo of age. Population studies indicate that the inverse relationship between birth weight and blood pressure is amplified with age. Thus, we tested the hypothesis that intrauterine growth restriction programs an age-related increase in blood pressure in male offspring. Growth-restricted offspring retained a significantly higher blood pressure at 12 but not at 18 mo of age compared with age-matched controls. Blood pressure was significantly increased in control offspring at 18 mo of age relative to control counterparts at 12 mo; however, blood pressure was not increased in growth-restricted at 18 mo relative to growth-restricted counterparts at 12 mo. Serum testosterone levels were not elevated in growth-restricted offspring relative to control at 12 mo of age. Thus, male growth-restricted offspring no longer exhibited a positive association between blood pressure and testosterone at 12 mo of age. Unlike hypertension in male growth-restricted offspring at 4 mo of age, inhibition of the renin-angiotensin system with enalapril (250 mg/l for 2 wk) did not abolish the difference in blood pressure in growth-restricted offspring relative to control counterparts at 12 mo of age. Therefore, these data suggest that intrauterine growth restriction programs an accelerated age-related increase in blood pressure in growth-restricted offspring. Furthermore, this study suggests that the etiology of increased blood pressure in male growth-restricted offspring at 12 mo of age differs from that at 4 mo of age.

Infant exposure to Chinese famine increased the risk of hypertension in adulthood: results from the China Health and Retirement Longitudinal Study

BACKGROUND

Early-life developmental adaptations in response to severe malnutrition may play a crucial role in susceptibility to hypertension. This study aimed to explore the associations between exposure to the Chinese famine (1959-1961) at fetal, infant and preschool stages during fetal life or childhood and the risk of hypertension in adulthood.

METHODS

We used the data of 1,966 adults born between 1956 and 1964 in selected families from the China Health and Retirement Longitudinal Study (CHARLS) national survey.

RESULTS

Prevalence of hypertension among adults in non-exposed, fetal-exposed, infant-exposed, and preschool-exposed cohorts was 18.9, 20.7, 28.7, and 23.4 %, respectively. In severely affected famine areas, only infant-exposed cohort had a significant increased risk of hypertension compared with non-exposed cohort (OR 2.12; 95 % CI 1.19, 3.79; P = 0.011), and the significance remained after adjusted gender, smoking, and drinking (OR 2.11; 95 % CI 1.18, 3.77; P = 0.012). After stratification by BMI and economic status, the risk of hypertension was higher for subjects with BMI ≥ 24 kg/m(2)(OR 2.09; 95 % CI 1.09, 4.01; P = 0.026) or high economic status(OR 2.26; 95 % CI 1.19, 4.31; P = 0.013) than those with BMI < 24 kg/m(2)(OR 1.65; 95 % CI 0.71, 3.83; P = 0.246) or low economic status (OR 2.18; 95 % CI 1.14, 4.18; P = 0.019) in infant-exposed cohort of severely affected famine areas. However, there was no consistent association observed in less severely affected area or other exposed cohorts in severely affected areas.

CONCLUSIONS

Infanthood exposed to famine might increase the risk of hypertension in adulthood, and a postnatal 'rich' nutrient environment further increased the risk.

In Utero Origins of Hypertension: Mechanisms and Targets for Therapy

The developmental origins of health and disease theory is based on evidence that a suboptimal environment during fetal and neonatal development can significantly impact the evolution of adult-onset disease. Abundant evidence exists that a compromised prenatal (and early postnatal) environment leads to an increased risk of hypertension later in life. Hypertension is a silent, chronic, and progressive disease defined by elevated blood pressure (>140/90 mmHg) and is strongly correlated with cardiovascular morbidity/mortality. The pathophysiological mechanisms, however, are complex and poorly understood, and hypertension continues to be one of the most resilient health problems in modern society. Research into the programming of hypertension has proposed pharmacological treatment strategies to reverse and/or prevent disease. In addition, modifications to the lifestyle of pregnant women might impart far-reaching benefits to the health of their children. As more information is discovered, more successful management of hypertension can be expected to follow; however, while pregnancy complications such as fetal growth restriction, preeclampsia, preterm birth, etc., continue to occur, their offspring will be at increased risk for hypertension. This article reviews the current knowledge surrounding the developmental origins of hypertension, with a focus on mechanistic pathways and targets for therapeutic and pharmacologic interventions.

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.

Uteroplacental insufficiency leads to hypertension, but not glucose intolerance or impaired skeletal muscle mitochondrial biogenesis, in 12-month-old rats

Growth restriction impacts on offspring development and increases their risk of disease in adulthood which is exacerbated with “second hits.” The aim of this study was to investigate if blood pressure, glucose tolerance, and skeletal muscle mitochondrial biogenesis were altered in 12-month-old male and female offspring with prenatal or postnatal growth restriction. Bilateral uterine vessel ligation induced uteroplacental insufficiency and growth restriction in offspring (Restricted). A sham surgery was also performed during pregnancy (Control) and some litters from sham mothers had their litter size reduced (Reduced litter), which restricted postnatal growth. Growth-restricted females only developed hypertension at 12 months, which was not observed in males. In Restricted females only homeostasis model assessment for insulin resistance was decreased, indicating enhanced hepatic insulin sensitivity, which was not observed in males. Plasma leptin was increased only in the Reduced males at 12 months compared to Control and Restricted males, which was not observed in females. Compared to Controls, leptin, ghrelin, and adiponectin were unaltered in the Restricted males and females, suggesting that at 12 months of age the reduction in body weight in the Restricted offspring is not a consequence of circulating adipokines. Skeletal muscle PGC-1α levels were unaltered in 12-month-old male and female rats, which indicate improvements in lean muscle mass by 12 months of age. In summary, sex strongly impacts the cardiometabolic effects of growth restriction in 12-month-old rats and it is females who are at particular risk of developing long-term hypertension following growth restriction.

Offspring’s hydromineral adaptive responses to maternal undernutrition during lactation

Early development, throughout gestation and lactation, represents a period of extreme vulnerability during which susceptibility to later metabolic and cardiovascular injuries increases. Maternal diet is a major determinant of the foetal and newborn developmental environment; maternal undernutrition may result in adaptive responses leading to structural and molecular alterations in various organs and tissues, such as the brain and kidney. New nephron anlages appear in the renal cortex up to postnatal day 4 and the last anlages to be formed develop into functional nephrons by postnatal day 10 in rodents. We used a model of undernutrition in rat dams that were food-restricted during the first half of the lactation period in order to study the long-term effects of maternal diet on renal development, behaviour and neural hydromineral control mechanisms. The study showed that after 40% food restriction in maternal dietary intake, the dipsogenic responses for both water and salt intake were not altered; Fos expression in brain areas investigated involved in hydromineral homeostasis control was always higher in the offspring in response to isoproterenol. This was accompanied by normal plasma osmolality changes and typical renal histology. These results suggest that the mechanisms for the control of hydromineral balance were unaffected in the offspring of these 40% food-restricted mothers. Undernutrition of the pups may not be as drastic as suggested by dams’ restriction.

Early life obesity and chronic kidney disease in later life

The prevalence of chronic kidney disease (CKD) has increased considerably with a parallel rise in the prevalence of obesity. It is now recognized that early life nutrition has life-long effects on the susceptibility of an individual to develop obesity, diabetes, cardiovascular disease and CKD. The kidney can be programmed by a number of intrauterine and neonatal insults. Low birth weight (LBW) is one of the most identifiable markers of a suboptimal prenatal environment, and the important intrarenal factors sensitive to programming events include decreased nephron number and altered control of the renin-angiotensin system (RAS). LBW complicated by accelerated catch-up growth is associated with an increased risk of obesity, hypertension and CKD in later life. High birth weight and exposure to maternal diabetes or obesity can enhance the risk for developing CKD in later life. Rapid postnatal growth per se may also contribute to the subsequent development of obesity and CKD regardless of birth weight and prenatal nutrition. Although the mechanisms of renal risks due to early life nutritional programming remain largely unknown, experimental and clinical studies suggest the burdening role of early life obesity in longstanding cardiovascular and renal diseases.

Transgenerational left ventricular hypertrophy and hypertension in offspring after uteroplacental insufficiency in male rats

Epidemiological studies have shown an association between low birthweight and adult disease development with transmission to subsequent generations. The aim of the present study was to examine the effect of intrauterine growth restriction in rats, induced by uteroplacental insufficiency, on cardiac structure, number, size, nuclearity, and adult blood pressure in first (F1) and second (F2) generation male offspring. Uteroplacental insufficiency or sham surgery was induced in F0 Wistar-Kyoto pregnant rats in late gestation giving rise to F1 restricted and control offspring, respectively. F1 control and restricted females were mated with normal males, resulting in F2 control and restricted offspring, respectively. F1 restricted male offspring were significantly lighter at birth (P < 0.05), but there were no differences in birthweight of F2 offspring. Left ventricular weights and volumes were significantly increased (P < 0.05) in F1 and F2 restricted offspring at day 35. Left ventricular cardiomyocyte number was not different in F1 and F2 restricted offspring. At 6 months-of-age, F1 and F2 restricted offspring had elevated blood pressure (8-15 mmHg, P < 0.05). Our findings demonstrate the emergence of left ventricular hypertrophy and hypertension, with no change in cardiomyocyte number, in F1 restricted male offspring, and this was transmitted to the F2 offspring. The findings support transgenerational programming effects.

Fathers that are born small program alterations in the next-generation preimplantation rat embryos

BACKGROUND

Low birth weight is associated with increased risk of adult cardiovascular and metabolic disease development, with recent studies highlighting transmission to subsequent generations via both maternal and paternal lines. However, the timing of parent-specific programming of disease risk to the next generation remains to be characterized.

OBJECTIVE

The aim of this study was to examine how paternal low birth weight affects the cellular and molecular physiology of the next-generation [second-generation (F2)] blastocysts, before uterine implantation.

METHODS

Uteroplacental insufficiency was surgically induced in Wistar Kyoto pregnant rats in late gestation, giving rise to first-generation restricted (born small) and sham-operated control (normal birth weight) male offspring, respectively. First-generation restricted and control male rats were naturally mated with normal females.

RESULTS

Resultant F2 blastocysts derived from restricted males displayed reduced expression of growth regulatory genes of the mammalian target of rapamycin pathway compared with F2 control blastocysts (9-74%; P < 0.05). No differences were found in F2 restricted blastocyst structural characteristics, cell number, or carbohydrate utilization at the time of blastocyst retrieval or after 24 h of in vitro culture. However, histidine, methionine, pyruvate, serine, and tryosine consumption and aspartate and leucine production were greater in F2 restricted outgrowth than in controls (P < 0.05).

CONCLUSIONS

The findings from this study clearly indicate that male rat offspring born small, arising from uteroplacental insufficiency, have physiologic alterations that manifest as modifications in gene expression levels and nutrient metabolism of F2 blastocysts, even in the absence of overt cellular growth differences. These data demonstrate that growth restriction and associated disease risk have the capacity to be transmitted to the next generation of offspring via the male germ line and is manifest as early as the blastocyst stage of development.

Pregnant growth restricted female rats have bone gains during late gestation which contributes to second generation adolescent and adult offspring having normal bone health

Low birth weight, due to uteroplacental insufficiency, results in programmed bone deficits in the first generation (F1). These deficits may be passed onto subsequent generations. We characterized the effects of being born small on maternal bone health during pregnancy; and aimed to characterize the contribution of the maternal environment and germ line effects to bone health in F2 offspring from mothers born small. Bilateral uterine vessel ligation (or sham) surgery was performed on female F0 WKY rats on gestational day 18 (term 22days) to induce uteroplacental insufficiency and fetal growth restriction. Control and Restricted F1 female offspring were allocated to a non-pregnant or pregnant group. To generate F2 offspring, F1 females were allocated to either non-embryo or embryo transfer groups. Embryo transfer was performed on gestational day 1, where second generation (F2) embryos were gestated (donor-in-recipient) in either a Control (Control-in-Control, Restricted-in-Control) or Restricted (Control-in-Restricted, Restricted-in-Restricted) mother. Restricted F1 females were born 10-15% lighter than Controls. Restricted non-pregnant females had shorter femurs, reduced trabecular and cortical bone mineral contents, trabecular density and bone geometry measures determined by peripheral quantitative computed tomography (pQCT) compared to non-pregnant Controls. Pregnancy restored the bone deficits that were present in F1 Restricted females. F2 non-embryo transfer male and female offspring were born of normal weight, while F2 embryo transfer males and females gestated in a Control mother (Control-in-Control, Restricted-in-Control) were heavier at birth compared to offspring gestated in a Restricted mother (Restricted-in-Restricted, Control-in-Restricted). Male F2 Restricted embryo groups (Restricted-in-Control and Restricted-in-Restricted) had accelerated postnatal growth. There was no transmission of bone deficits present at 35days or 6months in F2 offspring. Embryo transfer procedure had confounding effects preventing the separation of maternal environment and germ line contribution to outcomes. Deficits present in F1 non-pregnant Restricted females were absent during late gestation, indicating that pregnant F1 Restricted females experienced gains in bone. These beneficial maternal pregnancy adaptations may have prevented transmission of bone deficits to F2 offspring.

Fetal programming and cardiovascular pathology

Low birth weight serves as a crude proxy for impaired growth during fetal life and indicates a failure for the fetus to achieve its full growth potential. Low birth weight can occur in response to numerous etiologies that include complications during pregnancy, poor prenatal care, parental smoking, maternal alcohol consumption, or stress. Numerous epidemiological and experimental studies demonstrate that birth weight is inversely associated with blood pressure and coronary heart disease. Sex and age impact the developmental programming of hypertension. In addition, impaired growth during fetal life also programs enhanced vulnerability to a secondary insult. Macrosomia, which occurs in response to maternal obesity, diabetes, and excessive weight gain during gestation, is also associated with increased cardiovascular risk. Yet, the exact mechanisms that permanently change the structure, physiology, and endocrine health of an individual across their lifespan following altered growth during fetal life are not entirely clear. Transmission of increased risk from one generation to the next in the absence of an additional prenatal insult indicates an important role for epigenetic processes. Experimental studies also indicate that the sympathetic nervous system, the renin angiotensin system, increased production of oxidative stress, and increased endothelin play an important role in the developmental programming of blood pressure in later life. Thus, this review will highlight how adverse influences during fetal life and early development program an increased risk for cardiovascular disease including high blood pressure and provide an overview of the underlying mechanisms that contribute to the fetal origins of cardiovascular pathology.

Understanding the role of maternal diet on kidney development; an opportunity to improve cardiovascular and renal health for future generations

The leading causes of mortality and morbidity worldwide are cardiovascular disease (high blood pressure, high cholesterol and renal disease), cancer and diabetes. It is increasingly obvious that the development of these diseases encompasses complex interactions between adult lifestyle and genetic predisposition. Maternal malnutrition can influence the fetal and early life environment and pose a risk factor for the future development of adult diseases, most likely due to impaired organogenesis in the developing offspring. This then predisposes these offspring to cardiovascular disease and renal dysfunction in adulthood. Studies in experimental animals have further illustrated the significant impact maternal diet has on offspring health. Many studies report changes in kidney structure (a reduction in the number of nephrons in the kidney) in offspring of protein-deprived dams. Although the early studies suggested that increased blood pressure was also present in offspring of protein-restricted dams, this is not a universal finding and requires clarification. Importantly, to date, the literature offers little to no understanding of when in development these changes in kidney development occur, nor are the cellular and molecular mechanisms that drive these changes well characterised. Moreover, the mechanisms linking maternal nutrition and a suboptimal renal phenotype in offspring are yet to be discerned—one potential mechanism involves epigenetics. This review will focus on recent information on potential mechanisms by which maternal nutrition (focusing on malnutrition due to protein restriction, micronutrient restriction and excessive fat intake) influences kidney development and thereby function in later life.

Leptin in pregnancy and development: a contributor to adulthood disease?

Emerging research has highlighted the importance of leptin in fetal growth and development independent of its essential role in the maintenance of hunger and satiety through the modulation of neuropeptide Y and proopiomelanocortin neurons. Alterations in maternal-placental-fetal leptin exchange may modify the development of the fetus and contribute to the increased risk of developing disease in adulthood. In addition, leptin also plays an important role in reproductive functions, with plasma leptin concentrations rising in pregnant women, peaking during the third trimester. Elevated plasma leptin concentrations occur at the completion of organogenesis, and research in animal models has demonstrated that leptin is involved in the development and maturation of a number of organs, including the heart, brain, kidneys, and pancreas. Elevated maternal plasma leptin is associated with maternal obesity, and reduced fetal plasma leptin is correlated with intrauterine growth restriction. Alterations in plasma leptin during development may be associated with an increased risk of developing a number of adulthood diseases, including cardiovascular, metabolic, and renal diseases via altered fetal development and organogenesis. Importantly, research has shown that leptin antagonism after birth significantly reduces maturation of numerous organs. Conversely, restoration of the leptin deficiency after birth in growth-restricted animals restores the offspring's body weight and improves organogenesis. Therefore, leptin appears to play a major role in organogenesis, which may adversely affect the risk of developing a number of diseases in adulthood. Therefore, greater understanding of the role of leptin during development may assist in the prevention and treatment of a number of disease states that occur in adulthood.

Low female birth weight and advanced maternal age programme alterations in next-generation blastocyst development

Low birth weight is associated with an increased risk for adult disease development with recent studies highlighting transmission to subsequent generations. However, the mechanisms and timing of programming of disease transmission to the next generation remain unknown. The aim of this study was to examine the effects of low birth weight and advanced maternal age on second-generation preimplantation blastocysts. Uteroplacental insufficiency or sham surgery was performed in late-gestation WKY pregnant rats, giving rise to first-generation (F1) restricted (born small) and control offspring respectively. F1 control and restricted females, at 4 or 12 months of age, were naturally mated with normal males. Second-generation (F2) blastocysts from restricted females displayed reduced expression of genes related to growth compared with F2 control (P<0.05). Following 24 h culture, F2 restricted blastocysts had accelerated development, with increased total cell number, a result of increased trophectoderm cells compared with control (P<0.05). There were alterations in carbohydrate and serine utilisation in F2 restricted blastocysts and F2 restricted outgrowths from 4-month-old females respectively (P<0.05). F2 blastocysts from aged restricted females were developmentally delayed at retrieval, with reduced total cell number attributable to reduced trophectoderm number with changes in carbohydrate utilisation (P<0.05). Advanced maternal age resulted in alterations in a number of amino acids in media obtained from F2 blastocyst outgrowths (P<0.05). These findings demonstrate that growth restriction and advanced maternal age can alter F2 preimplantation embryo physiology and the subsequent offspring growth.

Physiological skeletal gains and losses in rat mothers during pregnancy and lactation are not observed following uteroplacental insufficiency

Fluctuations in maternal bone mass during pregnancy and lactation facilitate calcium transfer to offspring. Uteroplacental insufficiency causes fetal growth restriction and programs poor adult bone health. We aimed to characterise maternal skeletal phenotype during normal pregnancy and pregnancy complicated by uteroplacental insufficiency. Uteroplacental restriction (Restricted) or sham surgery (Control) was performed on gestational Day 18 (term=22 days) in pregnant Wistar-Kyoto rats. Maternal right femurs were collected on embryonic Day 20, postnatal Day 1 and Weeks 5, 7 and 9 postnatal. Dual-energy X-ray absorptiometry was used to quantify global bone mineral content, density and body composition. Peripheral quantitative computed tomography was utilised to determine trabecular and cortical content, density, circumferences and strength. Control rats exhibited expected reductions in trabecular and cortical content, density and bone strength from embryonic Day 20 to postnatal Day 1 (P<0.05). These skeletal alterations were absent in Restricted rats. By postnatal Day 7, bone parameters in Control and Restricted rats were not different from non-pregnant rats, indicating restoration of maternal bone. The lack of bone loss in mothers suffering uteroplacental insufficiency suggests that calcium transfer to pups would be impaired. This reduction in calcium availability is a likely contributor to the programming of poor adult bone health in growth-restricted offspring.

Birth weight, malnutrition and kidney-associated outcomes--a global concern

An adverse intrauterine environment is associated with an increased risk of elevated blood pressure and kidney disease in later life. Many studies have focused on low birth weight, prematurity and growth restriction as surrogate markers of an adverse intrauterine environment; however, high birth weight, exposure to maternal diabetes and rapid growth during early childhood are also emerging as developmental risk factors for chronic diseases. Altered programming of nephron number is an important link between exposure to developmental stressors and subsequent risk of hypertension and kidney disease. Maternal, fetal, and childhood nutrition are crucial contributors to these programming effects. Resource-poor countries experience the sequential burdens of fetal and childhood undernutrition and subsequent overnutrition, which synergistically act to augment the effects of developmental programming; this observation might explain in part the disproportionate burden of chronic disease in these regions. Numerous nutritional interventions have been effective in reducing the short-term risk of low birth weight and prematurity. Understanding the potential long-term benefits of such interventions is crucial to inform policy decisions to interrupt the developmental programming cycle and stem the growing epidemics of hypertension and kidney disease worldwide.

Effect of prenatal programming and postnatal rearing on glomerular filtration rate in adult rats

The present study examined whether a prenatal low-protein diet programs a decrease in glomerular filtration rate (GFR) and an increase in systolic blood pressure (BP). In addition, we examined whether altering the postnatal nutritional environment of nursing neonatal rats affected GFR and BP when rats were studied as adults. Pregnant rats were fed a normal (20%) protein diet or a low-protein diet (6%) during the last half of pregnancy until birth, when rats were fed a 20% protein diet. Mature adult rats from the prenatal low-protein group had systolic hypertension and a GFR of 0.38 ± 0.03 versus 0.57 ± 0.05 ml·min(-1)·100 g body wt(-1) in the 20% group (P < 0.01). In cross-fostering experiments, mothers continued on the same prenatal diet until weaning. Prenatal 6% protein rats cross-fostered to a 20% mother on day 1 of life had a GFR of 0.53 ± 0.05 ml·min(-1)·100 g body wt(-1), which was not different than the 20% group cross-fostered to a different 20% mother (0.45 ± 0.04 ml·min(-1)·100 g body wt(-1)). BP in the 6% to 20% group was comparable with the 20% to 20% group. Offspring of rats fed either 20% or 6% protein diets during pregnancy and cross-fostered to a 6% mother had elevated BP but a comparable GFR normalized to body weight as the 20% to 20% control group. Thus, a prenatal low-protein diet causes hypertension and a reduction in GFR in mature adult offspring, which can be modified by postnatal rearing.

Sex differences in the developmental origins of cardiovascular disease

The Developmental Origins of Health and Disease (DOHaD) proposes that adverse events during early life program an increased risk for cardiovascular disease. Experimental models provide proof of concept but also indicate that insults during early life program sex differences in adult blood pressure and cardiovascular risk. This review will highlight the potential mechanisms that contribute to the etiology of sex differences in the developmental programming of cardiovascular disease.

GDNF and MAPK-ERK pathway signaling is reduced during nephrogenesis following maternal under-nutrition

Maternal under-nutrition (MUN) during gestation results in growth-restricted newborns with reduced glomerular number and subsequent hypertension. We investigated dysregulation of glial derived neurotrophic factor (GDNF) and MAPK-ERK (mitogen-activated protein kinase-extracellular signal-regulated protein kinase) signal pathway gene expression following MUN. MUN rats were 50% food restricted from embryonic day 10 till postnatal day 1. Kidneys were harvested at embryonic day (E)20, and postnatal days (P)1 and 21. Kidney protein expression was determined by Western blot. At E20, protein expression of growth factor receptor alpha 1 (GFRα1) and phosphorylated ERK1/2 and mitogen-activated protein kinase kinase (MEK)1/2 were reduced significantly, and immunohistochemistry confirmed reduction of phosphorylated ERK (pERK) with maintenance of pERK localization. Total MEK and ERK were unchanged. At P1, only GFRα1 and pERK1/2 were reduced significantly while at P21, expression of all growth factors except total MEK was unchanged. Total MEK was increased. Glomerular number was decreased by 19% in P21 kidneys and blood pressure was increased in 12-week-old rats. In conclusion, GDNF and MAPK-ERK signaling are dysregulated during active nephrogenesis in fetal and early newborn offspring kidneys in the MUN model. This may be a key mechanism in reduced offspring nephrogenesis and programmed hypertension.

Cross-fostering and improved lactation ameliorates deficits in endocrine pancreatic morphology in growth-restricted adult male rat offspring

Uteroplacental insufficiency and poor postnatal nutrition impair adult glucose tolerance and insulin secretion in male rat offspring, which can be partially ameliorated by improving postnatal nutrition. Uteroplacental insufficiency was induced in the WKY rat on day 18 of pregnancy (Restricted) compared to sham-operated Controls. Pups were then cross-fostered onto Control or Restricted mothers one day after birth resulting in: (Pup-on-Mother) Control-on-Control, Control-on-Restricted, Restricted-on-Control and Restricted-on-Restricted. Endocrine pancreatic morphology and markers of intrinsic β-cell function and glucose homeostasis were assessed in male offspring at 6 months. Pancreatic and hepatic gene expression was quantified at postnatal day 7 and 6 months. Restricted pups were born 10-15% lighter than Controls and remained lighter at 6 months. Relative islet and β-cell mass were 51-65% lower in Restricted-on-Restricted compared to Controls at 6 months. Non-fasting plasma C-reactive protein levels were also increased, suggestive of an inflammatory response. Overall, the average number of islets, small islets and proportion of β-cells per islet correlated positively with birth weight. Intrinsic β-cell function, estimated by insulin secretion relative to β-cell mass, was unaffected by Restriction, suggesting that the in vivo functional deficit was attributable to reduced mass, not function. Importantly, these deficits were ameliorated when lactational nutrition was normalized in Restricted-on-Control offspring, who also showed increased pancreatic Igf1r, Pdx1 and Vegf mRNA expression at 7 days compared to Control-on-Control and Restricted-on-Restricted. This highlights lactation as a critical period for intervention following prenatal restraint, whereby deficits in endocrine pancreatic mass and associated impaired in vivo insulin secretion can be ameliorated.

Branched-chain amino acid supplemented diet during maternal food restriction prevents developmental hypertension in adult rat offspring

Maternal food restriction is known to cause developmental hypertension in offspring. We have previously shown that maternal high-protein diet can reverse fetal programming of hypertension and that branched-chain amino acid (BCAA) concentrations in maternal and fetal plasma were increased by maternal high-protein intake. Then, we hypothesized that isocaloric supplementation with BCAA to a maternal food restriction can reverse the adverse outcome. Pregnant rats were divided into four groups at 7.5 days postcoitum: normally nourished (NN) and 70% undernourished (UN) groups with and without BCAA supplementation (NN-standard diet (SD), NN-BCAA, UN-SD and UN-BCAA groups). Compared with pups in the NN groups, those in the UN-SD group had significantly increased systolic blood pressure (SBP) at 8 and 16 weeks of age (P < 0.05). However, the elevation of SBP was not observed in offspring in the UN-BCAA group. Offspring glomeruli number of the UN groups was significantly lower (P < 0.05) than that of the NN groups, independent of BCAA supplementation. Angiotensin II receptor type 2 (ATR2) mRNA and protein expression in the kidney was significantly augmented in the UN-BCAA group at 30 weeks of age. In conclusion, BCAA supplementation during maternal food restriction prevents developmental hypertension together with increased ATR2 expression in adult offspring kidney.

Maternal undernutrition upregulates apoptosis in offspring nephrogenesis

Maternal undernutrition (MUN) results in growth-restricted newborns with reduced nephron numbers that is associated with increased risk of hypertension and renal disease. The total adult complement of nephrons is set during nephrogenesis suggesting that MUN affects the staged development of nephrons in as yet unknown manner. A possible cause may be the increased renal apoptosis; therefore, we investigated whether apoptotic signaling and cell death were increased in MUN rat kidneys. Pregnant rat dams were fed an ad libitum diet [control] or were 50% food restricted (MUN) starting at embryonic day (E) 10. Male offspring kidneys (n = 5 each, MUN and control) were analyzed for mRNA using quantitative PCR (E20) and for protein expression using Western blotting and immunohistochemistry (E20 and postnatal day 1, P1). Apoptosis was measured by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. Upregulation of pro-apoptotic protein expression was detected at E20 (Fas receptor, caspase 9) and at P1 (caspase 3, Bax). The anti-apoptotic factor Bcl2 was significantly decreased in P1 kidneys. Kidney TUNEL showed apoptotic nuclei significantly increased in the P1 nephrogenic zone (MUN 3.3 + 0.3 v. C 1.6 + 0.5, P = 0.002). The majority of apoptotic nuclei co-localized to mesenchyme and pretubular aggregates in the nephrogenic zone. Differential regulation of apoptosis in mesenchyme and pretubular aggregates following parturition suggests a mechanism for nephropenia in gestational programming of the kidney.

Stage of perinatal development regulates skeletal muscle mitochondrial biogenesis and myogenic regulatory factor genes with little impact of growth restriction or cross-fostering

Foetal growth restriction impairs skeletal muscle development and adult muscle mitochondrial biogenesis. We hypothesized that key genes involved in muscle development and mitochondrial biogenesis would be altered following uteroplacental insufficiency in rat pups, and improving postnatal nutrition by cross-fostering would ameliorate these deficits. Bilateral uterine vessel ligation (Restricted) or sham (Control) surgery was performed on day 18 of gestation. Males and females were investigated at day 20 of gestation (E20), 1 (PN1), 7 (PN7) and 35 (PN35) days postnatally. A separate cohort of Control and Restricted pups were cross-fostered onto a different Control or Restricted mother and examined at PN7. In both sexes, peroxisome proliferator-activated receptor (PPAR)-γ coactivator-1α (PGC-1α), cytochrome c oxidase subunits 3 and 4 (COX III and IV) and myogenic regulatory factor 4 expression increased from late gestation to postnatal life, whereas mitochondrial transcription factor A, myogenic differentiation 1 (MyoD), myogenin and insulin-like growth factor I (IGF-I) decreased. Foetal growth restriction increased MyoD mRNA in females at PN7, whereas in males IGF-I mRNA was higher at E20 and PN1. Cross-fostering Restricted pups onto a Control mother significantly increased COX III mRNA in males and COX IV mRNA in both sexes above controls with little effect on other genes. Developmental age appears to be a major factor regulating skeletal muscle mitochondrial and developmental genes, with growth restriction and cross-fostering having only subtle effects. It therefore appears that reductions in adult mitochondrial biogenesis markers likely develop after weaning.

Growth restriction alters adult spatial memory and sensorimotor gating in a sex-specific manner

In Western society, impaired uteroplacental blood flow is the major cause of human intrauterine growth restriction. Infants born small and who experience late childhood accelerated growth have an increased risk of developing adult diseases. Recent studies also suggest a link between birth weight and altered adult behavior, particularly relating to motor function, learning and memory, depression and schizophrenia. The aim of this study was to determine the relative influence of prenatal and postnatal growth restriction on adult behavioral outcomes in male and female rats. Uteroplacental insufficiency was induced in Wistar Kyoto rats by bilateral uterine vessel ligation on day 18 of gestation producing growth-restricted offspring (Restricted group). The Control group had sham surgery. Another group underwent sham surgery, with a reduction in litter size to five at birth equivalent to the Restricted litter size (Reduced Litter group). At 6 months of age, a series of behavioral tests were conducted in male and female offspring. Growth restriction did not impair motor function. In fact, Restricted and Reduced Litter males showed enhanced motor performance compared with Controls (P < 0.05). Spatial memory was greater in Restricted females only (P < 0.05). The Porsolts test was unremarkable, however, males exhibited more depressive-like behavior than females (P < 0.05). A reduction in sensorimotor gating function was identified in Reduced Litter males and females (P < 0.05). We have demonstrated that growth restriction and/or a poor lactational environment can affect adult rat behavior, particularly balance and coordination, memory and learning, and sensorimotor gating function, in a sex-specific manner.

Alcohol exposure during late gestation: multiple developmental outcomes in sheep

Alcohol consumption during pregnancy remains common in many countries. Exposure to even low amounts of alcohol (i.e. ethanol) in pregnancy can lead to the heterogeneous fetal alcohol spectrum disorders (FASD), while heavy alcohol consumption can result in the fetal alcohol syndrome (FAS). FAS is characterized by cerebral dysfunction, growth restriction and craniofacial malformations. However, the effects of lower doses of alcohol during pregnancy, such as those that lead to FASD, are less well understood. In this article, we discuss the findings of recent studies performed in our laboratories on the effects of fetal alcohol exposure using sheep, in which we investigated the effects of late gestational alcohol exposure on the developing brain, arteries, kidneys, heart and lungs. Our studies indicate that alcohol exposure in late gestation can (1) affect cerebral white matter development and increase the risk of hemorrhage in the fetal brain, (2) cause left ventricular hypertrophy with evidence of altered cardiomyocyte maturation, (3) lead to a decrease in nephron number in the kidney, (4) cause altered arterial wall stiffness and endothelial and smooth muscle function and (5) result in altered surfactant protein mRNA expression, surfactant phospholipid composition and pro-inflammatory cytokine mRNA expression in the lung. These findings suggest that fetal alcohol exposure in late gestation can affect multiple organs, potentially increasing the risk of disease and organ dysfunction in later life.

Effect of low birth weight on women's health

PURPOSE

The theory of the developmental origins of health and disease hypothesizes that low birth weight (≤5.5 lb) indicative of poor fetal growth is associated with an increased risk of chronic, noncommunicable disease in later life, including hypertension, type 2 diabetes mellitus, and osteoporosis. Whether women are at greater risk than men is not clear. Experimental studies that mimic the cause of slow fetal growth are being used to examine the underlying mechanisms that link a poor fetal environment with later chronic disease and investigate how sex and age affect programmed risk. Thus, the aims of this review are to summarize the current literature related to the effect of low birth weight on women's health and provide insight into potential mechanisms that program increased risk of chronic disease across the lifespan.

METHODS

A search of PubMed was performed with the keywords low birth weight, women's health, female, and sex differences; additional terms included blood pressure, hypertension, renal, cardiovascular, obesity, glucose intolerance, type 2 diabetes, osteoporosis, bone health, reproductive senescence, menopause, and aging.

FINDINGS

The major chronic diseases associated with low birth weight include high blood pressure and cardiovascular disease, impaired glucose homeostasis and type 2 diabetes, impaired bone mass and osteoporosis, and early reproductive aging.

IMPLICATIONS

Low birth weight increases the risk of chronic disease in men and women. Low birth weight is also associated with increased risk of early menopause. Further studies are needed to fully address the effect of sex and age on the developmental programming of adult health and disease in women across their lifespan.

Developmental programming: variations in early growth and adult disease

Suboptimal conditions in utero are associated with the development of adult-onset diseases in offspring. Uteroplacental insufficiency in rats is a well-established animal model used to mimic and study the effects of developmental insults relevant to countries of abundant nutrient supply. However, wide-ranging outcomes for the offspring are apparent between the different investigators that use this model and also between cohorts generated in our laboratory. We aimed to explore the reasons for variability in rat models of uteroplacental insufficiency between different investigators and also between our own animal cohorts. We suggest differences in growth and disease development reflect uniqueness in susceptibility and highlight the complexity of interactions between genetic potential and environmental exposures. The impact of adverse exposures in utero has been described as having far-reaching effects that extend well beyond the first, directly exposed generation. However, the resulting phenotypes are not consistent between generations. This suggests that programmed effects are established de novo in each generation and challenges the prediction of disease. Characterization of growth and disease in the numerous rat models has led to our understanding of the impact of early life experiences on adult health. In order to drive the development of preventative and/or treatment strategies, future studies should focus on identifying the initial cause(s) of uteroplacental insufficiency, including genetic origins and the influence of poor diets.

Growth restriction in the rat alters expression of cardiac JAK/STAT genes in a sex-specific manner

Uteroplacental insufficiency resulting in intrauterine growth restriction has been associated with the development of cardiovascular disease, coronary heart disease and increased blood pressure, particularly in males. The molecular mechanisms that result in the programming of these phenotypes are not clear. This study investigated the expression of cardiac JAK/STAT signalling genes in growth restricted offspring born small due to uteroplacental insufficiency. Bilateral uterine vessel ligation was performed on day 18 of pregnancy to induce growth restriction (Restricted) or sham surgery (Control). Cardiac tissue at embryonic day (E) 20, postnatal day (PN) 1, PN7 and PN35 in male and female Wistar (WKY) rats (n=7–10 per group per age) was isolated and mRNA extracted. In the heart, there was an effect of age for males for all genes examined there was a decrease in expression after PN1. With females, JAK2 expression was significantly reduced after E20, while PI3K in females was increased at E30 and PN35. Further, mRNA expression was significantly altered in JAK/STAT signalling targets in Restricteds in a sex-specific manner. Compared with Controls, in males, JAK2 and STAT3 were significantly reduced in the Restricted, while in females SOCS3 was significantly increased and PI3K significantly decreased in the Restricted offspring. Finally, there were specific differences in the levels of gene expression within the JAK/STAT pathway when comparing males to females. Thus, growth restriction alters specific targets in the JAK/STAT signalling pathway, with altered JAK2 and STAT3 potentially contributing to the increased risk of cardiovascular disease in the growth restricted males.

Fetal and infant growth patterns and kidney function at school age

Low birth weight is associated with ESRD. To identify specific growth patterns in early life that may be related to kidney function in later life, we examined the associations of longitudinally measured fetal and infant growth with kidney function in school-aged children. This study was embedded in a population-based prospective cohort study among 6482 children followed from fetal life onward. Fetal and childhood growth was measured during second and third trimesters of pregnancy, at birth, and at 6, 12, 24, 36, and 48 months postnatally. At the age of 6 years, we measured kidney volume by ultrasound. GFR was estimated using blood creatinine levels. Higher gestational age-adjusted birth weight was associated with higher combined kidney volume and higher eGFR (per 1 SD score increase in birth weight; 1.27 cm(3) [95% confidence interval, 0.61 to 1.93] and 0.78 ml/min per 1.73 m2 [95% CI, 0.16 to 1.39], respectively). Fetal weight, birth weight, and weight at 6 months were positively associated with childhood kidney volume, whereas higher second trimester fetal weight was positively associated with higher GFR (all P values<0.05). Fetal and childhood lengths were not consistently associated with kidney function. In this cohort, lower fetal and early infant weight growth is associated with smaller kidney volume in childhood, whereas only lower fetal weight growth is associated with lower kidney function in childhood, independent of childhood growth. Whether these associations lead to an increased risk of kidney disease needs to be studied further.

Effect of postnatal maternal protein intake on prenatal programming of hypertension

This study examined whether postnatal maternal dietary protein deprivation during the time of nursing can program hypertension when the offspring are studied as adults. Rats were fed either a 6% or 20% protein diet during the second half of pregnancy and continued on the same diet while rats were nursing their pups. The neonates of all of the rats were cross-fostered to a different mother and studied as adults. Adult rats that had a normal prenatal environment but were reared by mothers fed a low-protein diet until weaning (20%-6%) were hypertensive, had a higher renal Na(+)-K(+)-2Cl(-) cotransporter (NKCC2) and Na(+)-Cl(-) cotransporter (NCC) protein abundance yet a comparable number of glomeruli, and had higher plasma renin and angiotensin II levels compared to control (20%-20%). Rats whose mothers were fed a 6% protein diet and cross-fostered to a different rat fed a 6% protein diet until weaning (6%-6%) were hypertensive, had elevated plasma renin and angiotensin II levels, and had a reduction in nephron number but had NKCC2 and NCC levels comparable to 20% to 20% offspring. The 6% to 20% had blood pressure and glomerular numbers comparable to 20% to 20% rats. The hypertension resulting from prenatal dietary protein deprivation can be normalized by improving the postnatal environment. Combined prenatal and postnatal maternal dietary protein deprivation and maternal dietary protein deprivation while nursing alone (20%-6%) results in hypertension, but the mechanism for the hypertension in these groups is different.

Why and how we determine nephron number

The total number of glomeruli (nephrons) in a kidney is an important microanatomical parameter for at least three reasons: it provides an index of the success/extent of nephrogenesis and can thereby provide insights into the roles of specific genes and feto-maternal environmental factors in nephrogenesis; low nephron number has been linked to an increased risk of cardiovascular and renal disease in adulthood; and knowledge of quantitative kidney microanatomy can illuminate our understanding of physiological mechanisms in health and disease. A range of methods has been used to count glomeruli in kidneys over the past 100 years, with design-based stereology (the physical disector/fractionator combination) considered the gold standard. However, this approach is labor-intensive and expensive, and therefore is not utilized by most laboratories. A new method for counting and sizing every glomerulus in the kidney has recently been described. This method involves in vivo labeling of glomeruli with cationic ferritin, and then magnetic resonance imaging (MRI) of the ex vivo kidney. Values are obtained in one sixth of the time of disector-based approaches. This new MRI method holds great promise for studies of glomerular number and size ex vivo and in vivo.

Adverse prenatal environment and kidney development: implications for programing of adult disease

The 'developmental origins of health and disease' hypothesis suggests that many adult-onset diseases can be attributed to altered growth and development during early life. Perturbations during gestation can be detrimental and lead to an increased risk of developing renal, cardiovascular, metabolic, and neurocognitive dysfunction in adulthood. The kidney has emerged as being especially vulnerable to insult at almost any stage of development resulting in a reduction in nephron endowment. In both humans and animal models, a reduction in nephron endowment is strongly associated with an increased risk of hypertension. The focus of this review is twofold: i) to determine the importance of specific periods during development on long-term programing and ii) to examine the effects of maternal perturbations on the developing kidney and how this may program adult-onset disease. Recent evidence has suggested that insults occurring around the time of conception also have the capacity to influence long-term health. Although epigenetic mechanisms are implicated in mediating these outcomes, it is unclear as to how these may impact on kidney development. This presents exciting new challenges and areas for research.

Embryo transfer cannot delineate between the maternal pregnancy environment and germ line effects in the transgenerational transmission of disease in rats

Adverse conditions in utero can have transgenerational effects, in the absence of a subsequent insult. We aimed to investigate the contribution of the maternal pregnancy environment vs. germ line effects in mediating alterations to cardiorenal and metabolic physiology in offspring from mothers born small. Uteroplacental insufficiency was induced by bilateral uterine artery and vein ligation (Restricted group) or sham surgery (Control group) in Wistar-Kyoto rats. Restricted and control female offspring (F1) were mated with either breeder males (embryo donor) or vasectomized males (embryo recipient). Embryo transfer was performed at embryonic day (E) 1, whereby second-generation (F2) embryos gestated (donor-in-recipient) in either a control (Cont-in-Cont, Rest-in-Cont) or restricted (Cont-in-Rest, Rest-in-Rest) mother. In male and female offspring, glomerular number and size were measured at postnatal day (PN) 35, and systolic blood pressure, glucose control, insulin sensitivity, and pancreatic β-cell mass were measured in separate sibling cohorts at 6 mo. Rest-in-Rest offspring were hypothesized to have similar characteristics (reduced growth, altered metabolic control, and hypertension) to non-embryo-transferred Rest, such that embryo transfer would not be a confounding experimental influence. However, embryo-transferred Rest-in-Rest offspring underwent accelerated growth during the peripubertal phase, followed by slowed growth between 2 and 3 mo of age compared with non-embryo-transferred Rest groups. Furthermore, renal function and insulin response to a glucose load were different to respective non-embryo-transferred groups. Our data demonstrate the long-term effects of in vitro embryo manipulation, which confounded the utility of this approach in delineating between the maternal pregnancy environment and germ line effects that drive transgenerational outcomes.

Loss of a kidney during fetal life: long-term consequences and lessons learned

Epidemiological studies reveal that children born with a solitary functioning kidney (SFK) have a greater predisposition to develop renal insufficiency and hypertension in early adulthood. A congenital SFK is present in patients with unilateral renal agenesis or unilateral multicystic kidney dysplasia, leading to both structural and functional adaptations in the remaining kidney, which act to mitigate the reductions in glomerular filtration rate and sodium excretion that would otherwise ensue. To understand the mechanisms underlying the early development of renal insufficiency in children born with a SFK, we established a model of fetal uninephrectomy (uni-x) in sheep, a species that similar to humans complete nephrogenesis before birth. This model results in a 30% reduction in nephron number rather than 50%, due to compensatory nephrogenesis in the remaining kidney. Similar to children with a congenital SFK, uni-x sheep demonstrate a progressive increase in arterial pressure and a loss of renal function with aging. This review summarizes the compensatory changes in renal hemodynamics and tubular sodium handling that drive impairments in renal function and highlights the existence of sex differences in the functional adaptations following the loss of a kidney during fetal life.

Transgenerational programming of fetal nephron deficits and sex-specific adult hypertension in rats

A developmental insult that restricts growth in the first generation has the potential to program disease in subsequent generations. The aim of this study was to ascertain transgenerational growth and cardio–renal effects, via the maternal line, in a rat model of utero–placental insufficiency. Bilateral uterine vessel ligation or sham surgery (offspring termed first generation; F1 Restricted and Control, respectively) was performed in WKY rats. F1 Restricted and Control females were mated with normal males to produce second generation (F2) offspring (Restricted and Control) studied from fetal (embryonic Day 20) to adult (12 months) life. F2 Restricted male and female fetuses had reduced (P < 0.05) nephron number (down 15–22%) but this deficit was not sustained postnatally and levels were similar to Controls at Day 35. F2 Restricted males, but not females, developed elevated (+16 mmHg, P < 0.05) systolic blood pressure at 6 months of age, which was sustained to 9 months. This was not explained by alterations to intra-renal or plasma components of the renin–angiotensin system. In a rat model of utero–placental insufficiency, we report alterations to F2 kidney development and sex-specific adult hypertension. This study demonstrates that low birthweight can have far-reaching effects that extend into the next generation.

How the kidney is impacted by the perinatal maternal environment to develop hypertension

Environmental conditions during perinatal development such as maternal undernutrition, maternal glucocorticoids, placental insufficiency, and maternal sodium overload can program changes in renal Na(+) excretion leading to hypertension. Experimental studies indicate that fetal exposure to an adverse maternal environment may reduce glomerular filtration rate by decreasing the surface area of the glomerular capillaries. Moreover, fetal responses to environmental insults during early life that contribute to the development of hypertension may include increased expression of tubular apical or basolateral membrane Na(+) transporters and increased production of renal superoxide leading to enhanced Na(+) reabsorption. This review will address the role of these potential renal mechanisms in the fetal programming of hypertension in experimental models induced by maternal undernutrition, fetal exposure to glucocorticoids, placental insufficiency, and maternal sodium overload in the rat.

Maternal high-fat diet programs rat offspring hypertension and activates the adipose renin-angiotensin system

OBJECTIVE

A maternal high-fat diet creates an increased risk of offspring obesity and systemic hypertension. Although the renal renin-angiotensin system (RAS) is known to regulate blood pressure, it is now recognized that the RAS is also activated in adipose tissue during obesity. We hypothesized that programmed offspring hypertension is associated with the activation of the adipose tissue RAS in the offspring of obese rat dams.

STUDY DESIGN

At 3 weeks of age, female rats were weaned to a high-fat diet (60% k/cal; n = 6) or control diet (10% k/cal; n = 6). At 11 weeks of age, these rats were mated and continued on their respective diets during pregnancy. After birth, at 1 day of age, subcutaneous adipose tissue was collected; litter size was standardized, and pups were cross-fostered to either control or high-fat diet dams, which created 4 study groups. At 21 days of age, offspring were weaned to control or high-fat diet. At 6 months of age, body fat and blood pressure were measured. Thereafter, subcutaneous and retroperitoneal adipose tissue was harvested from male offspring. Protein expression of adipose tissue RAS components were determined by Western blotting.

RESULTS

The maternal high-fat diet induced early and persistent alterations in offspring adipose RAS components. These changes were dependent on the period of exposure to the maternal high-fat diet, were adipose tissue specific (subcutaneous and retroperitoneal), and were exacerbated by a postnatal high-fat diet. Maternal high-fat diet increased adiposity and blood pressure in offspring, regardless of the period of exposure.

CONCLUSION

These findings suggest that programmed adiposity and the activation of the adipose tissue RAS are associated with hypertension in offspring of obese dams.

Developmental origins of chronic renal disease: an integrative hypothesis

Cardiovascular diseases are one of the leading causes of mortality. Hypertension (HT) is one of the principal risk factors associated with death. Chronic kidney disease (CKD), which is probably underestimated, increases the risk and the severity of adverse cardiovascular events. It is now recognized that low birth weight is a risk factor for these diseases, and this relationship is amplified by a rapid catch-up growth or overfeeding during infancy or childhood. The pathophysiological and molecular mechanisms involved in the “early programming” of CKD are multiple and partially understood. It has been proposed that the developmental programming of arterial hypertension and chronic kidney disease is related to a reduced nephron endowment. However, this mechanism is still discussed. This review discusses the complex relationship between birth weight and nephron endowment and how early growth and nutrition influence long term HT and CKD. We hypothesize that fetal environment reduces moderately the nephron number which appears insufficient by itself to induce long term diseases. Reduced nephron number constitutes a “factor of vulnerability” when additional factors, in particular a rapid postnatal growth or overfeeding, promote the early onset of diseases through a complex combination of various pathophysiological pathways.

Effect of fetal and child health on kidney development and long-term risk of hypertension and kidney disease

Developmental programming of non-communicable diseases is now an established paradigm. With respect to hypertension and chronic kidney disease, adverse events experienced in utero can affect development of the fetal kidney and reduce final nephron number. Low birthweight and prematurity are the most consistent clinical surrogates for a low nephron number and are associated with increased risk of hypertension, proteinuria, and kidney disease in later life. Rapid weight gain in childhood or adolescence further compounds these risks. Low birthweight, prematurity, and rapid childhood weight gain should alert clinicians to an individual's lifelong risk of hypertension and kidney disease, prompting education to minimise additional risk factors and ensuring follow-up. Birthweight and prematurity are affected substantially by maternal nutrition and health during pregnancy. Optimisation of maternal health and early childhood nutrition could, therefore, attenuate this programming cycle and reduce the global burden of hypertension and kidney disease in the future.

Short-term gestation, long-term risk: prematurity and chronic kidney disease

Thanks to remarkable advances in neonatal intensive care, infants who once had little chance for survival can now enter adulthood. Yet the consequences of premature birth or low birth weight (LBW) on nephrogenesis, final nephron number, and long-term kidney function are unclear. This review focuses on the theory, experimental evidence, and observational data that suggest an increased risk of chronic kidney disease (CKD) for infants born prematurely. Many premature and LBW infants begin life with an incomplete complement of immature nephrons. They are then exposed to a variety of external stressors that can hinder ongoing kidney development or cause additional nephron loss such as hemodynamic alterations, nephrotoxic medications, infections, and suboptimal nutrition. Acute kidney injury, in particular, may be a significant risk factor for the development of CKD. According to Brenner's hypothesis, patients with decreased nephron number develop hyperfiltration that results in sodium retention, hypertension, nephron loss, and CKD due to secondary focal segmental glomerulosclerosis. Because the risk of CKD in premature and LBW infants has not been accurately determined, there are no evidence-based recommendations for screening or management. Yet with the first generation of infants from the surfactant era only now reaching adulthood, it is possible that there is already an unrecognized epidemic of CKD. We suggest individualized, risk-based assessments of premature and LBW infants due to the increased risk of CKD and call for additional research into the long-term risk for CKD these infants face.

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.

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.