Fetal exposure to low protein maternal diet alters the susceptibility of young adult rats to sulfur dioxide-induced lung injury

Effect of Maternal Gradient Nutritional Restriction during Pregnancy on Mammary Gland Development in Offspring

We aimed to investigate the effect of different levels of nutritional restriction on mammary gland development during the embryonic period by gradient nutritional restriction in pregnant female mice. We started the nutritional restriction of 60 female CD-1(ICR) mice from day 9 of gestation based on 100%, 90%, 80%, 70% and 60% of ad libitum intake. After delivery, the weight and body fat of the offspring and the mother were recorded (n = 12). Offspring mammary development and gene expression were explored by whole mount and qPCR. Mammary development patterns of in offspring were constructed using Sholl analysis, principal component analysis (PCA) and regression analysis. We found that: (1) Mild maternal nutritional restriction (90-70% of ad libitum intake) did not affect offspring weight, while body fat percentage was more sensitive to nutritional restriction (lower at 80% ad libitum feeding). (2) A precipitous drop in mammary development and altered developmental patterns occurred when nutritional restriction ranged from 80% to 70% of ad libitum intake. (3) Mild maternal nutritional restriction (90% of ad libitum intake) promoted mammary-development-related gene expression. In conclusion, our results suggest that mild maternal nutritional restriction during gestation contributes to increased embryonic mammary gland development. When maternal nutritional restriction reaches 70% of ad libitum intake, the mammary glands of the offspring show noticeable maldevelopment. Our results help provide a theoretical basis for the effect of maternal nutritional restriction during gestation on offspring mammary development and a reference for the amount of maternal nutritional restriction.

Complex patterns of cell growth in the placenta in normal pregnancy and as adaptations to maternal diet restriction

The major milestones in mouse placental development are well described, but our understanding is limited to how the placenta can adapt to damage or changes in the environment. By using stereology and expression of cell cycle markers, we found that the placenta grows under normal conditions not just by hyperplasia of trophoblast cells but also through extensive polyploidy and cell hypertrophy. In response to feeding a low protein diet to mothers prior to and during pregnancy, to mimic chronic malnutrition, we found that this normal program was altered and that it was influenced by the sex of the conceptus. Male fetuses showed intrauterine growth restriction (IUGR) by embryonic day (E) 18.5, just before term, whereas female fetuses showed IUGR as early as E16.5. This difference was correlated with differences in the size of the labyrinth layer of the placenta, the site of nutrient and gas exchange. Functional changes were implied based on up-regulation of nutrient transporter genes. The junctional zone was also affected, with a reduction in both glycogen trophoblast and spongiotrophoblast cells. These changes were associated with increased expression of Phlda2 and reduced expression of Egfr. Polyploidy, which results from endoreduplication, is a normal feature of trophoblast giant cells (TGC) but also spongiotrophoblast cells. Ploidy was increased in sinusoidal-TGCs and spongiotrophoblast cells, but not parietal-TGCs, in low protein placentas. These results indicate that the placenta undergoes a range of changes in development and function in response to poor maternal diet, many of which we interpret are aimed at mitigating the impacts on fetal and maternal health.

They Are What You Eat: Can Nutritional Factors during Gestation and Early Infancy Modulate the Neonatal Immune Response?

The ontogeny of the human immune system is sensitive to nutrition even in the very early embryo, with both deficiency and excess of macro- and micronutrients being potentially detrimental. Neonates are particularly vulnerable to infectious disease due to the immaturity of the immune system and modulation of nutritional immunity may play a role in this sensitivity. This review examines whether nutrition around the time of conception, throughout pregnancy, and in early neonatal life may impact on the developing infant immune system.

Association between exposure to the Chinese famine during infancy and the risk of self-reported chronic lung diseases in adulthood: a cross-sectional study

OBJECTIVE

To examine the association between early-life exposure to the Chinese famine and the risk of chronic lung diseases in adulthood.

DESIGN

Data analysis from a cross-sectional survey.

SETTING AND PARTICIPANTS

4135 subjects were enrolled into the study from the China Health and Retirement Longitudinal Study (CHARLS) 2011-2012 baseline survey to analyse the associations between prenatal and early postnatal famine exposure and the risk of chronic lung diseases in adulthood.

MAIN OUTCOME MEASURES

Chronic lung diseases were defined based on self-reported information.

RESULTS

The prevalence of self-reported chronic lung diseases in fetus-exposed, infant-exposed, preschool-exposed, and non-exposed groups was 6.5%, 7.9%, 6.8%, and 6.1%, respectively. The risk of chronic lung diseases in the infant-exposed group was significantly higher (OR 1.95, 95% CI 1.10 to 3.44) than the non-exposed group in severely affected areas, even after adjusting for gender, smoking, and drinking, family economic status, and the highest educational attainment of the parents (OR 2.57, 95% CI 1.26 to 5.25). In addition, after stratification by gender and famine severity, we found that only infant exposure to the severe famine was associated with the elevated risk of chronic lung diseases among male adults (OR 3.16, 95% CI 1.17 to 8.51).

CONCLUSIONS

Severe famine exposure during the period of infancy might increase the risk of chronic lung diseases in male adults.

Proteinuria in aging rats due to low-protein diet during mid-gestation

Nephrogenesis in the rat starts mid-gestation and continues into lactation. Maternal low protein (LP) intake leads to renal injury in rats and associates with mild renal injury in humans. We hypothesized that LP during early nephrogenesis or throughout gestation would induce more renal injury in rat offspring than when LP was only present before nephrogenesis. Pregnant rats were fed LP diet (9% casein) at early gestation (LPE, day 0-7), mid (LPM, day 8-14), late (LPL, day 15-22) or throughout gestation (LPA, day 0-22) and compared to controls on 18% casein diet. Offspring were studied at 18 months. Renal injury was assessed by 24 h proteinuria, plasma urea, antioxidant enzyme activities, and apoptosis (Bax/Bcl2). Proteinuria was higher in LPM males and LPE and LPM females. In LPM males glutathione peroxidase activity was lower, while in LPE males catalase activity was higher. Antioxidants were not much affected in females. Bax expression was higher in LPM males and females, while Bcl2 expression was higher in LPA females. Thus even before nephrogenesis (day 0-7), LP impacted on renal integrity in adult life, while LP during a later phase (day 15-22) or throughout gestation had less effect. In summary, for aging rat kidney LP poses the greatest threat when restricted to early nephrogenesis.

Nutrient-restricted fetus and the cardio–renal connection in hypertensive offspring

A suboptimal intrauterine environment has a number of deleterious effects on fetal development and postpartum health outcomes. Epidemiological studies on several human populations have linked socioeconomic status and low birth weight to an increased incidence of diseases such as hypertension, diabetes, obesity and cardiovascular disease. A growing number of experimental studies in a variety of animal models demonstrate that maternal stressors, such as nutrition and reduced uterine perfusion, affect the intrauterine milieu and result in increased blood pressure in offspring. Several mechanisms appear to contribute to hypertension, including vascular dysfunction and increased peripheral resistance, altered cardio-renal structure and alterations in cardio-renal function. Although many studies have characterized models of developmentally generated hypertension, few have begun to seek therapeutic modalities to ameliorate its incidence. This review discusses recent work that refines hypotheses linking a suboptimal intrauterine environment to cardiovascular and renal phenotypes that have increased susceptibility to cardiovascular disease and hypertension.

Protein deprivation attenuates Hsp expression in fat tissue

For ruminants, dietary protein is the first limiting component to the utilization of low-quality forage. Throughout gestation, low-protein intake may result in prenatal programming that causes various metabolic disturbances and physiological modulations to dams and their developing embryos. We studied the effect of long-term low-protein diet (LPD) on physiological, biochemical, and molecular parameters of the energy status in gestating beef cows. LPD resulted in significant reductions in feed intake and heart rate and promoted a negative retained energy status already after 3 weeks. Elevated levels of plasma creatinine and non-esterified fatty acids indicate endogenous degradation of fat and protein as a response to the demands in energy and nitrogen. Increasing levels of β-hydroxybutyrate confirmed the negative energy status obtained by the physiological measurements. At the molecular level, subcutaneous fat, Hsp90, Hsp70, and proteasome subunits decreased significantly after 3 months on LPD, in parallel with an increase of adipocyte fatty acid-binding protein. These results may indicate a decrease in turn-over of proteins, at the cost of induced lipolysis, and suggest that the response to protein deprivation, when examined in an energy-storing tissue, includes downregulation of the constitutive heat shock proteins involved in the protein degradation pathway of energy production and upregulation of tissue-specific genes such as those involved in energy production from fat degradation.

Inhibition of TGF-β signaling and decreased apoptosis in IUGR-associated lung disease in rats

Intrauterine growth restriction is associated with impaired lung function in adulthood. It is unknown whether such impairment of lung function is linked to the transforming growth factor (TGF)-β system in the lung. Therefore, we investigated the effects of IUGR on lung function, expression of extracellular matrix (ECM) components and TGF-β signaling in rats. IUGR was induced in rats by isocaloric protein restriction during gestation. Lung function was assessed with direct plethysmography at postnatal day (P) 70. Pulmonary activity of the TGF-β system was determined at P1 and P70. TGF-β signaling was blocked in vitro using adenovirus-delivered Smad7. At P70, respiratory airway compliance was significantly impaired after IUGR. These changes were accompanied by decreased expression of TGF-β1 at P1 and P70 and a consistently dampened phosphorylation of Smad2 and Smad3. Furthermore, the mRNA expression levels of inhibitors of TGF-β signaling (Smad7 and Smurf2) were reduced, and the expression of TGF-β-regulated ECM components (e.g. collagen I) was decreased in the lungs of IUGR animals at P1; whereas elastin and tenascin N expression was significantly upregulated. In vitro inhibition of TGF-β signaling in NIH/3T3, MLE 12 and endothelial cells by adenovirus-delivered Smad7 demonstrated a direct effect on the expression of ECM components. Taken together, these data demonstrate a significant impact of IUGR on lung development and function and suggest that attenuated TGF-β signaling may contribute to the pathological processes of IUGR-associated lung disease.

Nutritionally mediated programming of the developing immune system

A growing body of evidence highlights the importance of a mother's nutrition from preconception through lactation in programming the emerging organ systems and homeostatic pathways of her offspring. The developing immune system may be particularly vulnerable. Indeed, examples of nutrition-mediated immune programming can be found in the literature on intra-uterine growth retardation, maternal micronutrient deficiencies, and infant feeding. Current models of immune ontogeny depict a "layered" expansion of increasingly complex defenses, which may be permanently altered by maternal malnutrition. One programming mechanism involves activation of the maternal hypothalamic-pituitary-adrenal axis in response to nutritional stress. Fetal or neonatal exposure to elevated stress hormones is linked in animal studies to permanent changes in neuroendocrine-immune interactions, with diverse manifestations such as an attenuated inflammatory response or reduced resistance to tumor colonization. Maternal malnutrition may also have a direct influence, as evidenced by nutrient-driven epigenetic changes to developing T regulatory cells and subsequent risk of allergy or asthma. A 3rd programming pathway involves placental or breast milk transfer of maternal immune factors with immunomodulatory functions (e.g. cytokines). Maternal malnutrition can directly affect transfer mechanisms or influence the quality or quantity of transferred factors. The public health implications of nutrition-mediated immune programming are of particular importance in the developing world, where prevalent maternal undernutrition is coupled with persistent infectious challenges. However, early alterations to the immune system, resulting from either nutritional deficiencies or excesses, have broad relevance for immune-mediated diseases, such as asthma, and chronic inflammatory conditions like cardiovascular disease.

Dietary composition programmes placental phenotype in mice

Dietary composition during pregnancy influences fetal and adult phenotype but its effects on placental phenotype remain largely unknown. Using molecular, morphological and functional analyses, placental nutrient transfer capacity was examined in mice fed isocaloric diets containing 23%, 18% or 9% casein (C) during pregnancy. At day 16, placental transfer of glucose, but not methyl-aminoisobutyric acid (MeAIB), was greater in C18 and C9 than C23 mice, in association with increased placental expression of the glucose transporter Slc2a1/GLUT1, and the growth factor Igf2. At day 19, placental glucose transport remained high in C9 mice while MeAIB transfer was less in C18 than C23 mice, despite greater placental weights in C18 and C9 than C23 mice. Placental System A amino acid transporter expression correlated with protein intake at day 19. Relative growth of transport verses endocrine zones of the placenta was influenced by diet at both ages without changing the absolute volume of the transport surface. Fetal weight was unaffected by diet at day 16 but was reduced in C9 animals by day 19. Morphological and functional adaptations in placental phenotype, therefore, occur to optimise nutrient transfer when dietary composition is varied, even subtly. This has important implications for the intrauterine programming of life expectancy.

Supplementation of a maternal low-protein diet in rat pregnancy with folic acid ameliorates programming effects upon feeding behaviour in the absence of disturbances to the methionine-homocysteine cycle

Maternal protein restriction in rat pregnancy is associated with altered feeding behaviour in later life. When allowed to self-select their diet, rats subject to prenatal undernutrition show an increased preference for fatty foods. The main aim of the present study was to evaluate the contribution of folic acid in the maternal diet to programming of appetite, since disturbances of the folate and methionine-homocysteine cycles have been suggested to impact upon epigenetic regulation of gene expression and hence programme long-term physiology and metabolism. Pregnant rats were fed diets containing either 9 or 18 % casein by weight, with folate provided at either 1 or 5 mg/kg diet. Adult male animals exposed to low protein (LP) in fetal life exhibited increased preference for high-fat food. Providing the higher level of folate in the maternal diet prevented this effect of LP, but offspring of rats fed 18 % casein diet with additional folate behaved in a similar manner to LP-exposed animals. Among day 20 gestation fetuses, it was apparent that both protein restriction and maternal folate supplementation could have adverse effects upon placental growth. Examination of methionine-homocysteine and folate cycle intermediates, tissue glutathione concentrations and expression of mRNA for methionine synthase, DNA methyltransferase 1 and methyltetrahydrofolate reductase revealed no gross disturbances of folate and one-carbon metabolism in either maternal or fetal tissue. The present findings indicated that any role for DNA methylation in programming of physiology is not related to major perturbations of folate metabolism, and is likely to be gene-specific rather than genome-wide.

Influence of age on the development of immunological lung response in intrauterine undernourishment

OBJECTIVE

We investigated the effect of intrauterine undernourishment on some features of asthma using a model of allergic lung inflammation in rats. The effects of age at which the rats were challenged (5 and 9 wk) were also evaluated.

METHODS

Intrauterine undernourished offspring were obtained from dams that were fed 50% of the nourished diet of counterparts and were immunized at 5 and 9 wk of age. They were tested for immunoglobulin E anti-ova titers (by passive cutaneous anaphylaxis), cell count in the bronchoalveolar fluid, leukotriene concentration, airway reactivity, mucus production, and blood corticosterone and leptin concentrations 21 d after immunologic challenge.

RESULTS

Intrauterine undernourishment significantly reduced the antigen-specific immunoglobulin E production, inflammatory cell infiltration into airways, mucus secretion, and production of leukotrienes B(4)/C(4) in the lungs in both age groups compared with respective nourished rats. The increased reactivity to methacholine that follows antigen challenge was not affected by intrauterine undernourishment. Corticosterone levels increased with age in the undernourished rats' offspring, but not in the nourished rats' offspring. Undernourished offspring already presented high levels of corticosterone before inflammatory stimulus and were not modified by antigen challenge. Leptin levels increased with challenge in the nourished rats but not in the undernourished rats and could not be related to corticosterone levels in the undernourished rats.

CONCLUSION

Intrauterine undernourishment has a striking and age-dependent effect on the offspring, reducing lung allergic inflammation.

A hierarchical analysis of transcriptome alterations in intrauterine growth restriction (IUGR) reveals common pathophysiological pathways in mammals

Intra-uterine growth restriction (IUGR) is a frequent disease, affecting up to 10% of human pregnancies and responsible for increased perinatal morbidity and mortality. Moreover, low birth weight is an important cause of the metabolic syndrome in the adult. Protein depletion during the gestation of rat females has been widely used as a model for human IUGR. By transcriptome analysis of control and protein-deprived rat placentas, we were able to identify 2543 transcripts modified more than 2.5 fold (1347 induced and 1196 repressed). Automatic functional classification enabled us to identify clusters of induced genes affecting chromosome structure, transcription, intracellular transport, protein modifications and apoptosis. In particular, we suggest the existence of a complex balance regulating apoptosis. Among repressed genes, we noted several groups of genes involved in immunity, signalling and degradation of noxious chemicals. These observations suggest that IUGR placentas have a decreased resistance to external aggression. The promoters of the most induced and most repressed genes were contrasted for their composition in putative transcription factor binding sites. There was an over-representation of Zn finger (ZNF) proteins and Pdx1 (pancreatic and duodenal homeobox protein 1) putative binding sites. Consistently, Pdx1 and a high proportion of ZNF genes were induced at the transcriptional level. A similar analysis of ZNF promoters showed an increased presence of putative binding sites for the Tata box binding protein (Tbp). Consistently again, we showed that the Tbp and TBP-associated factors (Tafs) were up-regulated in IUGR placentas. Also, samples of human IUGR and control placentas showed that human orthologous ZNFs and PDX1 were transcriptionally induced, especially in non-vascular IUGR. Immunohistochemistry revealed increased expression of PDX1 in IUGR human placentas. In conclusion, our approach permitted the proposition of hypotheses on a hierarchy of gene inductions/repressions leading to massive transcriptional alterations in the IUGR placenta, in humans and in rodents.

Wheezing and eczema in relation to infant anthropometry: evidence of developmental programming of disease in childhood

Early life factors and, in particular, the fetal environment have been suggested to programme risk of allergic disease in later life. Diversion of nutrients away from immune organs towards the brain, a process termed brain sparing, has been proposed as a mechanism underpinning this association. The study population was a group of 256 seven-year old children from the UK recruited from two general practitioner surgeries. Historical anthropometric data from birth to age three and current anthropometry were assessed as predictors of parent-reported wheeze and eczema. Eczema at seven years was not related to any anthropometric indices at birth or during infancy. A smaller head circumference at 10-15 days of age was noted in children with current wheeze at age 7 years (P = 0.018) and this relationship persisted after adjustment for current anthropometry and confounders. Comparison of children with head circumference over 36.5 cm at 10-15 days with those with head circumference under 35.5 cm, showed reduced odds for wheeze at 7 years (OR 0.12, 95% CI 0.03-0.44, P(trend) = 0.009). These data suggest that factors that determine fetal growth may be associated with wheeze in childhood and support the developmental origins of health and disease hypothesis. Brain sparing does not appear to play a role in this early life programming.

The association between birthweight and longevity in the rat is complex and modulated by maternal protein intake during fetal life

Maternal protein restriction in rat pregnancy has been suggested to reduce lifespan of the resulting offspring by inducing fetal growth retardation, followed by postnatal catch-up growth. We tested the hypothesis that lifespan could be programmed in both males and females by exposure to undernutrition at specific stages of fetal development. Protein restriction throughout gestation significantly reduced lifespan in both males and females. Low birthweight increased longevity, whilst rapid postnatal growth had a detrimental effect. There was no evidence that undernutrition programmed lifespan through oxidative processes in the major organs. Fetal programming is an important contributor to the ageing process.

Increased glutathione conjugate transport: a possible compensatory protection mechanism against oxidative stress in obesity?

OBJECTIVE

To compare glutathione S-conjugate transport in obese and nonobese persons, and how glutathione S-conjugates are involved in the antioxidant status in obesity.

MATERIALS AND METHODS

The efflux of glutathione conjugates and malondialdehyde (MDA) levels were measured in erythrocytes of obese (N = 33) and nonobese (N = 28) persons at every 30 min during a 120 min incubation time in vitro. 2,4-dinitrophenyl-S-glutathione (DNP-SG) represented the glutathione S-conjugate.

RESULTS

The efflux of conjugate in erythrocytes from obese subjects (708 +/- 147 DNP-SG efflux nmol/ml erythrocytes/h) was significantly higher than that of control group (490 +/- 105 DNP-SG efflux nmol/ml erythrocytes/h) (P < 0.05). At all time points measured (30-120 min), there was an increase in DNP-SG efflux in obese group (P < 0.05). This is manifested by a decrease in cellular DNP-SG levels. The susceptibility of erythrocytes to in vitro 1-chloro-2,4-dinitrobenzene (CDNB)-induced oxidative stress were greater for cells of control group (P < 0.05), although hemolysis sensitivity of these cells are not different between both groups (P > 0.05). Following CDNB pretreatment, incubation of erythrocyte with vanadate, a DNP-SG transport inhibitor, resulted in an increase of MDA in both groups. However, in this case, the difference in susceptibility was not related to obesity. On the other hand, while erythrocyte glutathione level was lower in obese subjects (79% of control) than in controls (P < 0.05), the adenosine 5'-triphosphate (ATP) levels, the enzyme activities of glutathione S-transferase (GST) and the conjugation capacities of the erythrocytes were not different between groups (P>0.05).

CONCLUSION

Obesity may increase erythrocyte glutathione conjugate transport independent from ATP and GST activity that may protect against MDA formation in vitro.

Developmental programming of health and disease

The environment encountered in fetal and neonatal life exerts a profound influence on physiological function and risk of disease in adult life. Epidemiological evidence suggests that impaired fetal growth followed by rapid catch-up in infancy is a strong predictor of obesity, hypertension, non-insulin-dependent diabetes and CHD. Whilst these associations have been widely accepted to be the product of nutritional factors operating in pregnancy, evidence from human populations to support this assertion is scarce. Animal studies clearly demonstrate that there is a direct association between nutrient imbalance in fetal life and later disease states, including hypertension, diabetes, obesity and renal disease. These associations are independent of changes in fetal growth rates. Experimental studies examining the impact of micro- or macronutrient restriction and excess in rodent pregnancy provide clues to the mechanisms that link fetal nutrition to permanent physiological changes that promote disease. Exposure to glucocorticoids in early life appears to be an important consequence of nutrient imbalance and may lead to alterations in gene expression that have major effects on tissue development and function. Epigenetic mechanisms, including DNA methylation, may also be important processes in early-life programming.

Integrating the ideas of life course across cellular, individual, and population levels in cancer causation

Cells, individuals, and societies are complex systems in which the integrity of structure and function is protected through tight regulation and control. For each level of organization, health represents the ability to maintain integrity in response to the wider environment. Critical stages during growth and development act as checkpoints, where choice is exercised, and help determine future direction. Important among factors influencing the checkpoints include the availability of nutrients or foods within the immediate environment. At the cellular and whole-body levels, this information can be communicated to future generations. Recent work on the developmental origins of adult disease indicate specific factors that set limits on structure and function and potentially limit the capacity of the cell and individual to respond to environmental stressors that represent potential risk factors for neoplastic change. Epigenetic mechanisms modulate structure and function at the cellular and tissue levels, reflecting the potential for the growth and development of individuals, and reflect the food and nutrients available to the body as a whole and within the wider society. Understanding the nature and the interaction of the critical factors that determine and regulate variable stable and unstable gene expression will be increasingly important in characterizing abnormal cellular function and risk of disease for individuals and populations. This will require the ability to synthesize large data sets within and between different levels of organization to develop and refine a deeper understanding of how the systems are effectively integrated and regulated within and across generations and where this fails in the genesis of cancer.

Programming of hepatic antioxidant capacity and oxidative injury in the ageing rat

Exposure to undernutrition in fetal life increases the susceptibility of humans and animals to major disease states in adult life. Studies of rodents exposed to protein restriction during fetal life indicate that lifespan is reduced, a finding that is the opposite of the well-documented improvement in longevity noted with post-weaning caloric restriction. The maternal low-protein (MLP) model of rat pregnancy therefore provides a suitable vehicle to consider how nutrition in fetal life may programme mechanisms of ageing. Pregnant rats were fed control (n = 7) or MLP diet (n = 7) throughout pregnancy. At birth, increased oxidation of hepatic proteins was noted, and this appeared related to activity of glutathione reductase. Older offspring were studied at 4, 16, 30 and 44 weeks of age and analyses revealed that MLP exposure in utero produced sex-specific differences in oxidant:antioxidant balance. In male offspring, MLP increased protein carbonyl concentrations in the liver (P = 0.013) and increased glutathione peroxidase activity (P = 0.018). These programmed changes were absent in the female offspring. The data support the hypothesis that reduced lifespan in rats subject to prenatal protein restriction is a consequence of enhanced oxidative processes promoting apoptosis and loss of tissue function. Mechanisms of ageing appear to be subject to nutritional programming during early development.

Does a nephron deficit in rats predispose to salt-sensitive hypertension?

AIM

This study tested the hypothesis that a nephron deficit predisposes rats to salt-sensitive hypertension in adulthood.

METHODS

Female Wistar-Kyoto rats were fed a low (9%) or a normal (20%) protein diet during pregnancy and lactation. Male, birth-weight-matched offspring were paired. One rat from each pair was perfusion fixed at 4 weeks of age and the other rat at 40 weeks of age. Kidneys were removed and nephron number and total renal filtration surface area (FSA) determined using unbiased stereological techniques. The rats that were allowed to grow to adulthood had tail-cuff systolic blood pressure and body weight determined twice weekly. Between 30 and 40 weeks of age, a normal or a high-salt diet was fed to the rats.

RESULTS

The offspring of rats fed the low-protein diet were significantly smaller at birth, and at 4 weeks of age they had a significant reduction in kidney volume, nephron number, and total renal FSA when compared to controls. Tail-cuff systolic blood pressure in the offspring from 4 to 29 weeks of age did not significantly differ between the two groups. Administration of a high-salt diet from 30 to 40 weeks of age led to a significant increase in blood pressure in both dietary treatment groups; however, it was not exacerbated in the rats exposed to the low-protein diet in utero.

CONCLUSIONS

Maternal protein restriction in rats did not lead to salt-sensitive hypertension. Nephron endowment and FSA did not correlate with blood pressure in adulthood.

Synthesis of erythrocyte glutathione in healthy adults consuming the safe amount of dietary protein

BACKGROUND

The finding that plasma glutathione turnover decreases as dietary protein intake decreases suggests that the safe amount of dietary protein, although sufficient for maintenance of nitrogen balance, may be insufficient for maintenance of cellular glutathione.

OBJECTIVE

Our objective was to determine the effect of the safe protein intake on the erythrocyte glutathione synthesis rate and its relation with urinary 5-L-oxoproline excretion.

DESIGN

Erythrocyte glutathione synthesis and urinary 5-L-oxoproline excretion were measured in young adults (6 men and 6 women) by using an infusion of [(13)C(2)]glycine on 3 occasions: initially during the subjects' habitual protein intake (1.13 g.kg(-1).d(-1)) and on days 3 and 10 of consumption of a diet providing the safe protein intake (0.75 g.kg(-1).d(-1)).

RESULTS

Compared with baseline values, the fractional synthesis rate of erythrocyte glutathione was significantly lower (P < 0.05) on days 3 and 10 of the diet with the safe protein intake. Urinary 5-L-oxoproline excretion increased significantly (P < 0.05) above baseline by the third day of the diet with the safe protein intake and remained elevated. Erythrocyte glutathione concentrations and absolute synthesis rates decreased by day 3 but recovered to baseline values by day 10. Erythrocyte concentrations of cysteine, methionine, and serine remained unchanged, whereas erythrocyte concentrations of glycine, glutamic acid, and glutamine increased significantly by day 10.

CONCLUSION

During adaptation to the safe amount of dietary protein, there are changes in the concentration and kinetics of erythrocyte glutathione that suggest a reduced antioxidant capacity and possible increased susceptibility to oxidant stress.

Fetal programming of cardiovascular function through exposure to maternal undernutrition

A substantial and robust body of epidemiological evidence indicates that prenatal dietary experience may be a factor determining cardiovascular disease risk. Retrospective cohort studies indicate that low birth weight and disproportion at birth are powerful predictors of later disease risk. This prenatal influence on non-communicable disease in later life has been termed programming. Maternal nutritional status has been proposed to be the major programming influence on the developing fetus. The evidence from epidemiological studies of nutrition, fetal development and birth outcome is, however, often weak and inconclusive. The validity of the nutritional programming concept is highly dependent on experimental studies in animals. The feeding of low-protein diets in rat pregnancy results in perturbations in fetal growth and dimensions at birth. The offspring of rats fed low-protein diets exhibit a number of metabolic and physiological disturbances, and are consistently found to have high blood pressure from early postnatal life. This experimental model has been used to explore potential mechanisms of programming through which maternal diet may programme the cardiovascular function of the fetus. Indications from this work are that fetal exposure to maternally-derived glucocorticoids plays a key role in the programming mechanism. Secondary to this activity, the fetal hypothalamic-pituitary-adrenal axis may stimulate renin-angiotensin system activity, resulting in increased vascular resistance and hypertension.

Age-related changes in antioxidant enzyme activities and lipid peroxidation in lungs of control and sulfur dioxide exposed rats

Antioxidant defenses within the lung are pivotal in preventing damage from oxidative toxicants. There have also been several reports with conflicting results on the antioxidant system during aging. In this study, we attempted to investigate age-related alterations in both antioxidant enzyme activities and thiobarbituric acid-reactive substances (TBARS), a product of lipid peroxidation, in the whole lung of control and sulfur dioxide (SO2) exposed rats of different age groups (3-, 12-, and 24-months-old). Swiss-Albino Male rats were exposed to 10 ppm. SO2 1 hr/day, 7 days/week for 6 weeks. The antioxidant enzymes examined include Cu,Zn-superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and glutathione S-transferase (GST). A mixed pattern of age-associated alterations in antioxidant activities was observed. SOD, GSH-Px and GST activities were increased with age, but CAT activity was decreased. Lung SOD, GSH-Px and GST activities were also increased in response to SO2. The level of TBARS was increased with age. SO2 exposure stimulated lipid peroxide formation in the lung as indicated by an increase in the level of TBARS. These findings suggest that both aging and SO2 exposure may impose an oxidative stress to the body. We conclude that the increase in the activities of the antioxidant enzymes of the lung during aging, could be interpreted as a positive feedback mechanism in response to rising lipid peroxidation.

Atopy, lung function, and obstructive airways disease after prenatal exposure to famine

BACKGROUND

Associations have been found between a large head size at birth and atopy, and between low birth weight and obstructive airways disease. A study was undertaken of people born around the time of the Dutch famine in 1944-5 to determine the effects of maternal malnutrition during specific periods of gestation on the prevalence of obstructive airways disease and atopy.

METHODS

Nine hundred and twelve people aged about 50, born at term between November 1943 and February 1947 in Amsterdam, were asked about their medical history. Lung function was measured in 733 and serum concentrations of total IgE and specific IgE against mite, pollen and cat were measured in 726. Those exposed in late, mid, and early gestation (exposed participants) were compared with those born before or conceived after the famine (non-exposed participants).

RESULTS

Exposure to famine during gestation affected neither the concentrations of total or specific IgE nor lung function values. The prevalence of obstructive airways disease was increased in people exposed to famine in mid gestation (odds ratio adjusted for sex 1.7, 95% confidence interval (CI) 1.1 to 2.6) and tended to be higher in those exposed in early gestation (odds ratio 1.5, 95% CI 0. 9 to 2.6).

CONCLUSIONS

The observed increase in the prevalence of obstructive airways disease in people exposed to famine in mid and early gestation was not parallelled by effects on IgE concentrations or lung function. The link between exposure to famine in mid and early gestation and obstructive airways disease in adulthood suggests that fetal lungs can be permanently affected by nutritional challenges during periods of rapid growth.

Intrauterine programming of cardiovascular disease by maternal nutritional status

The origins of cardiovascular disease are related to genetic factors, postnatal environmental and behavioral influences, and also the environment experienced in utero. Patterns of disproportionate fetal growth consistent with maternal undernutrition appear to be predictive of later hypertension and coronary heart disease. These findings from epidemiologic studies are strongly supported by animal studies. Experimental models are suggestive of a role for glucocorticoid hormones in the intrauterine programming of cardiovascular function. New understanding of the relationships between maternal diet and the development and maturation of fetal tissues may enable prevention of cardiovascular disease by intervention in early life.