Modest maternal protein restriction fails to program adult hypertension in female rats

Modest maternal dietary protein restriction in the rat leads to hypertension in adult male offspring. The purpose of this study was to determine whether female rats are resistant to developing the increased blood pressure seen in male rats after maternal protein restriction. Pregnant rats were fed a normal protein (19%, NP) or low-protein (8.5%, LP) diet throughout gestation. Renal renin protein and ANG II levels were reduced by 50-65% in male LP compared with NP pups, but were not suppressed in female LP compared with female NP. Mean arterial pressure in conscious, chronically instrumented adult female offspring (22 wk) was not different in LP (LP: 120 +/- 3 mmHg vs. NP: 121 +/- 2 mmHg), and glomerular filtration rate was also not different in LP vs. NP. The number of glomeruli per kidney was similar in adult LP and NP female offspring (LP: 26,050 +/- 2,071 vs. NP: 26,248 +/- 1,292, NP), and individual glomerular volume was also not different (LP: 0.92 +/- 0.11 10(6) microm(3), LP vs. NP: 1.07 +/- 0.11 10(6) microm(3)); the total volume of all glomeruli per kidney was also not significantly different. Thus female rats are relatively resistant to the programming for adult hypertension by perinatal protein restriction that we have described in males. This resistance may be due to the fact that modest maternal protein restriction does not reduce the number of glomeruli with which females are endowed as it does in males. The intrarenal renin-angiotensin system during development may play a key role in this protective effect of female gender.     

Adult cardiorenal benefits from postnatal fish oil supplement in rat offspring of low-protein pregnancies

We investigated the effect of fish oil (FO) treatment on cardiorenal structure of adult offspring from low-protein pregnancies. Three month old offspring were assigned to eight groups (four male groups and four female groups, n=8 each) (NP=normal-protein diet, LP=low-protein diet): NP, LP, NP plus FO, and LP plus FO. Left ventricle and kidney were analyzed with light microscopy and stereology. The both sexes of LP offspring showed 30% lower birth weights than the respective NP offspring and high blood pressure (BP) levels in adulthood which was efficiently reduced by FO treatment. In the heart, FO treated the cardiomyocyte hypertrophy, the vascularization impairment, and decreased the cardiomyocyte loss usually observed in adult LP offspring. In the kidney, FO treated, in the male, the imbalance of the cortex-to-medulla ratio observed in both sexes of LP offspring, and reduced the glomeruli loss in the LP offspring. The positive correlation between the number of cardiomyocyte nuclei later in life and the body mass (BM) at birth was significant only in both sexes of LP offspring and this correlation disappeared in LP plus fish oil offspring. The positive correlation between the number of glomeruli later in life and the BM at birth was significant in NP male offspring and in both sexes of LP offspring. In conclusion, FO supplement, which is a rich source of n-3 fatty acids (DHA and EPA), has beneficial effects on BP control and cardiac and renal adverse remodeling usually seen in offspring of the LP pregnancies.     

Birth weight and postnatal dietary protein level affect performance, muscle metabolism and meat quality in pigs

Intrauterine growth restriction (IUGR), resulting in low birth body weight (LBW) occurs naturally in pigs. However, IUGR may also cause persistent changes in physiology and metabolism resulting in poorer performance, organogenesis and meat quality. As IUGR pigs have a lower daily gain from birth to slaughter they may differ in utilization of nutrients and requirements for dietary protein compared with their larger littermates. Thus, the objective in this study was to examine the interaction between birth body weight (BW) and the postnatal dietary protein level, in relation to postnatal performance, organogenesis, muscle metabolism and meat quality. The experiment was carried out with offspring from 16 purebred Danish Landrace gilts mated to Danish Landrace boars. The female and entire male pigs with LBW that survived at weaning were compared with the female and male pigs with the highest/high birth body weight (HBW) within each litter. The offspring were reared individually from weaning and were fed ad libitum a diet containing either a normal level of protein (NP) for optimal growth or an isocaloric diet containing a 30% lower protein content (LP) from 3 weeks to 150 days of age. At slaughter, we found no interactions between birth weight group and dietary protein level for any of the measured traits. The relative crown-rump length (cm/kg) at birth indicates that LBW pigs were thinner than HBW pigs. Daily gain and feed intake were reduced by 14% and 10%, respectively, while the kg feed/kg gain was slightly increased by 3% in LBW pigs compared with HBW pigs. The LP diet reduced daily gain by 27% due to reduced feed intake and increased kg feed/kg gain by 12% and 21%, respectively compared with the NP diet. LBW male pigs produced meat with a higher shear force than male HBW pigs and also LP pigs produced meat with higher shear force than NP pigs. The activity of lactate dehydrogenase in the Longissimus dorsi muscle (LD) was reduced in pigs fed the LP diet. Calpastatin was increased in LD of LBW pigs and decreased in pigs fed the NP diet. In conclusion, these results suggest a rejection of our hypothesis that low birth weight littermates have a lower requirement for dietary protein compared with heavy weight littermates. Furthermore, LBW male pigs and LP fed pigs of both genders produced less tender meat than HBW pigs or NP fed pigs, respectively.     

Combined prenatal and postnatal protein restriction influences adult kidney structure, function, and arterial pressure

The effects of prenatal protein restriction on adult renal and cardiovascular function have been studied in considerable detail. However, little is known about the effects of life-long protein restriction, a common condition in the developing world. Therefore, we determined in rats the effects of combined pre- and postnatal protein restriction on adult arterial pressure and renal function and responses to increased dietary sodium. Nephron number was also determined. Male Sprague-Dawley rats were born to mothers fed a low [8% (wt/wt), LP] or normal [20% (wt/wt), NP] isocaloric protein diet throughout pregnancy and maintained on these diets after birth. At postnatal day 135, nephron number, mean arterial pressure (MAP), and renal function were determined. A high-NaCl [8.0% (wt/wt), high-salt] diet was fed to a subset of rats from weaning. MAP was less in LP than in NP rats (120 +/- 2 vs. 128 +/- 2 mmHg, P < 0.05) and was not significantly altered by increased salt intake. Nephron number was 31% less in LP than in NP rats (P < 0.001). The volume of individual glomeruli was also less in LP than in NP rats, as were calculated effective renal plasma flow and glomerular filtration rate. Glomerular filtration rate, but not effective renal plasma flow, appeared to be increased by high salt intake, particularly in LP rats. In conclusion, protein restriction induced a severe nephron deficit, but MAP was lower, rather than higher, in protein-restricted than in control rats in adulthood. These findings indicate that the postnatal environment plays a key role in determining the outcomes of developmental programming.     

Effects of dietary protein restriction on nephron number in the mouse

In rats, maternal protein restriction reduces nephron endowment and often leads to adult hypertension. Sex differences in these responses have been identified. The molecular and genetic bases of these phenomena can best be identified in a mouse model, but effects of maternal protein restriction on kidney development have not been examined in mice. Therefore, we determined how combined prenatal and postnatal protein restriction in mice affects organ weight, glomerular number and dimensions, and renal expression of angiotensin receptor mRNA, in both male and female offspring. C57/BL6/129sv mice received either a normal (20% wt/wt; NP) or low (9% wt/wt; LP) protein diet during gestation and postnatal life. Offspring were examined at postnatal day 30. Protein restriction retarded growth of the kidney, liver, spleen, heart, and brain. All organs except the brain weighed less in female than male offspring. Protein restriction increased normalized (to body weight) brain weight, with females having relatively heavier brains than males. The effects of protein restriction were not sex dependent, except that normalized liver weight was reduced in males but increased in females. Glomerular volume, but not number, was greater in female than in male mice. Maternal protein restriction reduced nephron endowment similarly in male and female mice. Renal expression of AT(1A) receptor mRNA was approximately sixfold greater in female than male NP mice, but similar in male LP and female LP mice. We conclude that maternal protein restriction reduces nephron endowment in mice. This effect provides a basis for future studies of developmental programming in the mouse.     

Maternal protein restriction induce skeletal muscle changes without altering the MRFs MyoD and myogenin expression in offspring

Stimuli during pregnancy, such as protein restriction, can affect morphophysiological parameters in the offspring with consequences in adulthood. The phenomenon known as fetal programming can cause short- and long-term changes in the skeletal muscle phenotype. We investigated the morphology and the myogenic regulatory factors (MRFs) MyoD and myogenin expression in soleus, SOL; oxidative and slow twitching and in extensor digitorum longus, EDL; glycolytic and fast twitching muscles in the offspring of dams subjected to protein restriction during pregnancy. Four groups of male Wistar offspring rats were studied. Offspring from dams fed a low-protein diet (6?% protein, LP) and normal protein diet (17?% protein, NP) were euthanized at 30 and 112?days old, and their muscles were removed and kept at ?80?°C. Muscles histological sections (8?μm) were submitted to a myofibrillar adenosine triphosphatase histochemistry reaction for morphometric analysis. Gene and protein expression levels of MyoD and myogenin were determined by RT-qPCR and western blotting. The major findings observed were distinct patterns of morphological changes in SOL and EDL muscles in LP offspring at 30 and 112?days old without changes in MRFs MyoD and myogenin expression. Our results indicate that maternal protein restriction followed by normal diet after birth induced morphological changes in muscles with distinct morphofunctional characteristics over the long term, but did not alter the MRFs MyoD and myogenin expression. Further studies are necessary to better understand the mechanisms underlying the maternal protein restriction response on skeletal muscle.     

Maternal green tea polyphenol intake during lactation attenuates kidney injury in high-fat-diet-fed male offspring programmed by maternal protein restriction in rats

Maternal malnutrition is known to increase the risk of obesity in offspring. We investigated whether green tea extract (GTE) intake during lactation affects obesity-related fibrosis and inflammation in the kidney of high-fat-diet-fed adult offspring of protein-restricted-diet-fed dams during pregnancy and lactation. Pregnant Wistar rats received diets containing 20% (normal-protein, NP) or 8% (low-protein, LP) casein, and they received 0%-, 0.12%- or 0.24%-GTE-containing LP diets (LP/LP, LP/LGT and LP/HGT, respectively) during lactation. At weaning, the pups that received a diet providing 13% (normal-fat, NF) or 45% (high-fat, HF) energy from fat were divided into five groups: NP/NP/NF, LP/LP/NF, LP/LP/HF, LP/LGT/HF and LP/HGT/HF. At week 45, the degree of fibrosis; macrophage infiltration; protein expression levels of TGF-β; and mRNA levels of TNF-α, DNMT, UHRF1 and histone lysine methyltransferase (G9a) in the kidneys of male offspring were examined. The area of fibrosis and TGF-βlevels increased in the LP/LP/HF group. Conversely, the fibrotic areas and TGF-β levels in the LP/HGT/HF group decreased (33% and 31%, respectively) compared with those in the LP/LP/HF group. The number of macrophages and mRNA levels of TNF-α in the LP/HGT/HF group decreased (34% and 29%, respectively) compared with those in the LP/LP/HF group. DNMT1, UHRF1 and G9a mRNA levels in the LP/HGT/HF group decreased compared with those in the LP/LP/HF group. In conclusion, GTE intake during lactation attenuated tubulointerstitial fibrosis and macrophage infiltration by down-regulating epigenetic modulators such as DNMT1, UHRF1 and G9a in the kidney of HF-diet-fed adult offspring programmed by maternal protein restriction.     

Protein-restriction diet during the suckling phase programs rat metabolism against obesity and insulin resistance exacerbation induced by a high-fat diet in adulthood

Protein restriction during the suckling phase can malprogram rat offspring to a lean phenotype associated with metabolic dysfunctions later in life. We tested whether protein-caloric restriction during lactation can exacerbate the effect of a high-fat (HF) diet at adulthood. To test this hypothesis, we fed lactating Wistar dams with a low-protein (LP; 4% protein) diet during the first 2 weeks of lactation or a normal-protein (NP; 23% protein) diet throughout lactation. Rat offspring from NP and LP mothers received a normal-protein diet until 60 days old. At this time, a batch of animals from both groups was fed an HF (35% fat) diet, while another received an NF (7% fat) diet. Maternal protein-caloric restriction provoked lower body weight and fat pad stores, hypoinsulinemia, glucose intolerance, higher insulin sensitivity, reduced insulin secretion and altered autonomic nervous system (ANS) function in adult rat offspring. At 90 days old, NP rats fed an HF diet in adulthood displayed obesity, impaired glucose homeostasis and altered insulin secretion and ANS activity. Interestingly, the LP/HF group also presented fat pad and body weight gain, altered glucose homeostasis, hyperleptinemia and impaired insulin secretion but at a smaller magnitude than the NP-HF group. In addition, LP/HF rats displayed elevated insulin sensitivity. We concluded that protein-caloric restriction during the first 14 days of life programs the rat metabolism against obesity and insulin resistance exacerbation induced by an obesogenic HF diet.     

Early Low Protein Diet Aggravates Unbalance between Antioxidant Enzymes Leading to Islet Dysfunction

Background

Islets from adult rat possess weak antioxidant defense leading to unbalance between superoxide dismutase (SOD) and hydrogen peroxide-inactivating enzymatic activities, catalase (CAT) and glutathione peroxidase (GPX) rending them susceptible to oxidative stress. We have shown that this vulnerability is influenced by maternal diet during gestation and lactation.

Methodology/Principal Findings

The present study investigated if low antioxidant activity in islets is already observed at birth and if maternal protein restriction influences the development of islet antioxidant defenses. Rats were fed a control diet (C group) or a low protein diet during gestation (LP) or until weaning (LPT), after which offspring received the control diet. We found that antioxidant enzymatic activities varied with age. At birth and after weaning, normal islets possessed an efficient GPX activity. However, the antioxidant capacity decreased thereafter increasing the potential vulnerability to oxidative stress. Maternal protein malnutrition changed the antioxidant enzymatic activities in islets of the progeny. At 3 months, SOD activity was increased in LP and LPT islets with no concomitant activation of CAT and GPX. This unbalance could lead to higher hydrogen peroxide production, which may concur to oxidative stress causing defective insulin gene expression due to modification of critical factors that modulate the insulin promoter. We found indeed that insulin mRNA level was reduced in both groups of malnourished offspring compared to controls. Analyzing the expression of such critical factors, we found that c-Myc expression was strongly increased in islets from both protein-restricted groups compared to controls.

Conclusion and Significance

Modification in antioxidant activity by maternal low protein diet could predispose to pancreatic islet dysfunction later in life and provide new insights to define a molecular mechanism responsible for intrauterine programming of endocrine pancreas.     

根田鼠母体捕食应激效应与Trivers-Willard 模型的关系

本研究了根田鼠母体捕食应激对其子代出生、断乳和成体体重、窝性比及死亡率的作用,检验Trivers—Willard模型的2个前提条件、母体应激激素在母体投资中的作用,以及母体捕食应激效应与该模型的关系。将妊娠根田鼠母体暴露于其捕食艾鼬,母体应激子代的出生和断乳体重均显降低;到成体,雄性体重有此效应,而雌性体重则接近对照。出生窝性比无变化,但成体窝性比向雌性偏斜。不同年龄阶段的死亡率无显变化,但累计死亡率明显增大。处理雄性子代在断乳和成体时的皮质酮含量显增高,而雌性子代则无显变化,从而验证了Trivers-Willard模型的2个前提条件,提出应激母体激素参与母体对子代的投资观点,并认为,母体捕食应激使根田鼠子代成体窝性比向雌性偏斜的生理投资符合进化稳定对策。     

Maternal vitamin d deficiency delays glomerular maturity in f1 and f2 offspring

Background

There is a high prevalence of vitamin D insufficiency in women of reproductive age.

Methods

This work studied the first two generations of offspring (F1 and F2) of Swiss mice from mothers fed one of two diets: SC (standard chow) or VitD- (vitamin D-deficient). Functional and developmental kidney measurements were taken.

Results

The first two generations of the VitD- group had higher blood pressure at 6 months of age than the offspring of the SC group as well as an increase in renin and AT1r expression. However, at all ages, both F1 and F2 VitD- mice had shorter glomerular diameters, and diet played a significant role in the total variation. Both the F1 and F2 generations of the VitD- group had more immature glomeruli than offspring from the SC group. Immature glomeruli begin to disappear at 10 days, but at this age, F1-VitD- mice had more immature and mature glomeruli than F1-SC mice. At 6 months of age, F1-VitD- mice exhibited more glomeruli, while F2-VitD- mice exhibited the same number of glomeruli as F2-SC mice, but fewer glomeruli compared to the F1-VitD group. Both diet and generation account for the total variation in the number of glomeruli. Decreases in urine output and podocin expression and increases in urea and creatinine in the urine were observed in F1 offspring.

Conclusion

These findings demonstrate that maternal vitamin D deficiency accompanies changes in the renal expression of important factors that may retard the maturation of glomeruli by extending the period of nephrogenesis.     

Consumption of a high-salt diet by ewes during pregnancy alters nephrogenesis in 5-month-old offspring

Maternal nutrition during pregnancy can affect kidney development in the foetus, which may lead to adverse consequences in the mature kidney. It was expected that high-salt intake by pregnant ewes would lead to a reduction in foetal glomerular number but that the ovine kidney would adapt to maintain homoeostasis, in part by increasing the size of each glomerulus. Merino ewes that were fed either a control (1.5% NaCl) or high-salt (10.5% NaCl) diet during pregnancy, as well as their 5-month-old offspring, were subjected to a dietary salt challenge, and glomerular number and size and sodium excretion were measured. The high-salt offspring had 20% fewer glomeruli compared with the control offspring (P < 0.001), but they also had larger glomerular radii compared with the control offspring (P < 0.001). Consequently, the cross-sectional area of glomeruli was 18% larger in the high-salt offspring than in the control offspring (P < 0.05). There was no difference in the daily urinary sodium excretion between the two offspring groups (P > 0.05), although the high-salt offspring produced urine with a higher concentration of sodium. Our results demonstrated that maternal high-salt intake during pregnancy affected foetal nephrogenesis, altering glomerular number at birth. However, the ability to concentrate and excrete salt was not compromised, which indicates that the kidney was able to adapt to the reduction in the number of glomeruli.     

母鼠营养不良导致子代在生命早期出现糖脂代谢紊乱及其机制探讨

为了探讨母鼠孕期和哺乳期营养不良对子代生命早期糖脂代谢的影响及其机制,文章对孕期和哺乳期母鼠分别喂养高脂饮食、低蛋白饮食和正常饮食,观察其子鼠断乳时(3周龄)糖脂代谢指标,并采用荧光定量PCR方法检测子鼠肝组织氧化物酶增殖物激活受体γ(PPARγ)基因的表达情况。结果表明：子鼠在3周龄时,与正常饮食组相比,低蛋白饮食组子鼠出生体重(7.36±0.91 vs 8.94±1.39,P<0.0001)较低,体长较短(12.27±0.53 vs 13.44±0.36,P<0.0001);高脂饮食组子鼠体重(9.53±0.68 vs 7.36±0.91,P<0.0001)和体长(13.22±0.35 vs 12.27±0.53,P<0.0001)均高于低蛋白饮食组;另外,高脂饮食组子鼠腹腔糖耐量实验30 min和60 min血糖明显高于正常饮食组(P<0.001),且高脂饮食组30 min血糖水平也明显高于低蛋白饮食组(P<0.001),高脂饮食组子鼠糖耐量曲线下面积明显大于正常饮食组(P<0.001)。另外,与正常饮食组相比,高脂饮食组子鼠空腹胆固醇水平明显升高(1.64±0.21 vs 1.18±0.16,P<0.01),低蛋白饮食组空腹胆固醇水平明显下降(0.96±0.09 vs 1.18±0.16,P<0.05)。荧光定量PCR结果显示,在低蛋白饮食组和高脂饮食组,其子鼠肝组织PPARγ基因表达量均明显高于正常饮食组(P<0.05)。结果显示,母鼠妊娠期和哺乳期高脂饮食与低蛋白饮食均可以诱导子鼠在发育早期出现糖脂代谢紊乱,PPARγ基因可能在其中参与了重要的调控作用。     

Involvement of Renal Corpuscle microRNA Expression on Epithelial-to-Mesenchymal Transition in Maternal Low Protein Diet in Adult Programmed Rats

Prior study shows that maternal protein-restricted (LP) 16-wk-old offspring have pronounced reduction of nephron number and arterial hypertension associated with unchanged glomerular filtration rate, besides enhanced glomerular area, which may be related to glomerular hyperfiltration/overflow and which accounts for the glomerular filtration barrier breakdown and early glomerulosclerosis. In the current study, LP rats showed heavy proteinuria associated with podocyte simplification and foot process effacement. TGF-β1 glomerular expression was significantly enhanced in LP. Isolated LP glomeruli show a reduced level of miR-200a, miR-141, miR-429 and ZEB2 mRNA and upregulated collagen 1α1/2 mRNA expression. By western blot analyzes of whole kidney tissue, we found significant reduction of both podocin and nephrin and enhanced expression of mesenchymal protein markers such as desmin, collagen type I and fibronectin. From our present knowledge, these are the first data showing renal miRNA modulation in the protein restriction model of fetal programming. The fetal-programmed adult offspring showed pronounced structural glomerular disorders with an accentuated and advanced stage of fibrosis, which led us to state that the glomerular miR-200 family would be downregulated by TGF-β1 action inducing ZEB 2 expression that may subsequently cause glomeruli epithelial-to-mesenchymal transition.     

Cholecystokinin-8S levels in discrete hypothalamic nuclei of weanling rats exposed to maternal protein malnutrition

Perinatal malnutrition and growth retardation at birth are suggested to be important risk factors for the development of overweight and syndrome X in later life. Underlying mechanisms are unknown. Body weight and food intake are regulated, e.g. by hypothalamic neuropeptidergic systems which are thought to be highly vulnerable to persisting malorganization due to perinatal malnutrition. To investigate possible consequences for hypothalamic cholecystokinin-8S (CCK-8S) in the offspring, pregnant Wistar rats were fed an 8% protein diet during pregnancy and lactation (low-protein group; LP) while control mothers (CO) received a 17% protein isocaloric standard diet. LP offspring displayed underweight at birth (P < 0.05) and during suckling (P < 0.001), while leptin levels were not altered. At weaning, under basal conditions CCK-8S was decreased in LP offspring in the paraventricular hypothalamic nucleus and arcuate hypothalamic nucleus (P < 0.05), as well as in the dorsomedial hypothalamic nucleus, lateral hypothalamic area and ventromedial hypothalamic nucleus (P < 0.01). In summary, these data indicate (1) an inhibition of the satiety peptide CCK-8S in main regulators of body weight and food intake in low-protein malnourished newborn rats; (2) no direct relationship of hypothalamic CCK-8S to circulating leptin at this age; and (3) no neurochemical signs of hypothalamic CCKergic dysregulation in this animal model at the age of weaning.