Placental mitochondrial dysfunction with metabolic diseases: Therapeutic approaches

Both obesity and gestational diabetes mellitus (GDM) lead to poor maternal and fetal outcomes, including pregnancy complications, fetal growth issues, stillbirth, and developmental programming of adult-onset disease in the offspring. Increased placental oxidative/nitrative stress and reduced placental (trophoblast) mitochondrial respiration occur in association with the altered maternal metabolic milieu of obesity and GDM. The effect is particularly evident when the fetus is male, suggesting a sexually dimorphic influence on the placenta. In addition, obesity and GDM are associated with inflexibility in trophoblast, limiting the ability to switch between usage of glucose, fatty acids, and glutamine as substrates for oxidative phosphorylation, again in a sexually dimorphic manner. Here we review mechanisms underlying placental mitochondrial dysfunction: its relationship to maternal and fetal outcomes and the influence of fetal sex. Prevention of placental oxidative stress and mitochondrial dysfunction may improve pregnancy outcomes. We outline pathways to ameliorate deficient mitochondrial respiration, particularly the benefits and pitfalls of mitochondria-targeted antioxidants.     

Maternal protein restriction reduces expression of angiotensin I-converting enzyme 2 in rat placental labyrinth zone in late pregnancy

Both the systemic and the uteroplacental renin-angiotensin system (RAS) display dramatic changes during pregnancy. However, whether gestational protein insufficiency affects the expressions of RAS in the placenta remains unknown. In this study, we hypothesized that the expression of Ace2 in the placental labyrinth was reduced by maternal protein restriction. Pregnant Sprague-Dawley rats were fed a normal diet or a low-protein diet (LP) from Day 1 of pregnancy until they were killed at Day 14 or Day 18. The labyrinth zone (LZ) of the placenta was then dissected and snap frozen for expression analysis by quantitative real-time PCR of Ace, Ace2, Agtr1a, Agtr1b, and Agtr2. Formalin-fixed placentas were used for immunohistochemical analysis on ACE and ACE2 proteins. The findings include 1) the expression of Ace2 in rat LZ was reduced by maternal protein restriction in late pregnancy; 2) ACE protein was mainly present in syncytiotrophoblasts, whereas ACE2 protein was found predominantly in fetal mesenchymal tissue and fetal capillaries; 3) Agtr1a was predominant in the rat LZ, and its mRNA levels, but not protein levels, were reduced by LP; 4) expressions of Ace, Ace2, and Agtr1a in the rat LZ and their response to LP occurred in a gender-dependent manner. These results may indicate that a reduced expression of Ace2 and perhaps an associated reduction in angiotensin (1-7) production in the placenta by maternal protein restriction may be responsible for fetal growth restriction and associated programming of adulthood hypertension.     

Acute supplementation of amino acids increases net protein accretion in IUGR fetal sheep

Placental insufficiency decreases fetal amino acid uptake from the placenta, plasma insulin concentrations, and protein accretion, thus compromising normal fetal growth trajectory. We tested whether acute supplementation of amino acids or insulin into the fetus with intrauterine growth restriction (IUGR) would increase net fetal protein accretion rates. Late-gestation IUGR and control (CON) fetal sheep received acute, 3-h infusions of amino acids (with euinsulinemia), insulin (with euglycemia and euaminoacidemia), or saline. Fetal leucine metabolism was measured under steady-state conditions followed by a fetal muscle biopsy to quantify insulin signaling. In CON, increasing amino acid delivery rates to the fetus by 100% increased leucine oxidation rates by 100%. In IUGR, amino acid infusion completely suppressed fetal protein breakdown rates but increased leucine oxidation rate by only 25%, resulting in increased protein accretion rates by 150%. Acute insulin infusion, however, had very little effect on amino acid delivery rates, fetal leucine disposal rates, or fetal protein accretion rates in CON or IUGR fetuses despite robust signaling of the fetal skeletal muscle insulin-signaling cascade. These results indicate that, when amino acids are given directly into the fetal circulation independently of changes in insulin concentrations, IUGR fetal sheep have suppressed protein breakdown rates, thus increasing net fetal protein accretion.     

Impacts of arginine nutrition on embryonic and fetal development in mammals

Embryonic loss and intrauterine growth restriction (IUGR) are significant problems in humans and other animals. Results from studies involving pigs and sheep have indicated that limited uterine capacity and placental insufficiency are major factors contributing to suboptimal reproduction in mammals. Our discovery of the unusual abundance of the arginine family of amino acids in porcine and ovine allantoic fluids during early gestation led to the novel hypothesis that arginine plays an important role in conceptus (embryo and extra-embryonic membranes) development. Arginine is metabolized to ornithine, proline, and nitric oxide, with each having important physiological functions. Nitric oxide is a vasodilator and angiogenic factor, whereas ornithine and proline are substrates for uterine and placental synthesis of polyamines that are key regulators of gene expression, protein synthesis, and angiogenesis. Additionally, arginine activates the mechanistic (mammalian) target of rapamycin cell signaling pathway to stimulate protein synthesis in the placenta, uterus, and fetus. Thus, dietary supplementation with 0.83 % l-arginine to gilts consuming 2 kg of a typical gestation diet between either days 14 and 28 or between days 30 and 114 of pregnancy increases the number of live-born piglets and litter birth weight. Similar results have been reported for gestating rats and ewes. In sheep, arginine also stimulates development of fetal brown adipose tissue. Furthermore, oral administration of arginine to women with IUGR has been reported to enhance fetal growth. Collectively, enhancement of uterine as well as placental growth and function through dietary arginine supplementation provides an effective solution to improving embryonic and fetal survival and growth.     

Maternal-fetal hepatic and placental metabolome profiles are associated with reduced fetal growth in a rat model of maternal obesity

Introduction

Maternal obesity is associated with a range of pregnancy complications, including fetal growth restriction (FGR), whereby a fetus fails to reach its genetically determined growth. Placental insufficiency and reduced nutrient transport play a role in the onset of FGR.

Objectives

Metabolomic profiling was used to reveal altered maternal and fetal metabolic pathways in a model of diet induced obesity during pregnancy, leading to reduced fetal growth.

Methods

We examined the metabolome of maternal and fetal livers, and placenta following a high fat and salt intake. Sprague–Dawley rats were assigned to (a) control diet (CD; 1 % salt, 10 % kcal from fat), (b) high salt diet (SD; 4 % salt, 10 % kcal from fat), (c) high fat diet (HF; 1 % salt, 45 % kcal from fat) or (d) high-fat high-salt diet (HFSD; 4 % salt, 45 % kcal from fat) 21 days prior to pregnancy and during gestation. Metabolites from maternal and fetal livers, and placenta were identified using gas and liquid chromatography combined with mass spectrometry.

Results

Maternal HF intake resulted in reduced fetal weight. Altered metabolite profiles were observed in the HF maternal and fetal liver, and placenta. Polyunsaturated fatty acid metabolism was significantly altered in maternal and fetal liver by maternal fat intake.

Conclusion

Excess of linoleic and α-linoleic acid (essential fatty acids) may be detrimental during placentation and associated with a reduction in fetal weight. Additionally, maternal, placental and fetal response to increased fat consumption seems likely to involve palmitoleic acid utilization as an adaptive response during maternal obesity.

     

Metabolism of glucose by fetus and placenta of sheep. The effects of normal fluctuations in uterine blood flow

The metabolism by the fetus and placenta of [2-3H, U-14C]glucose infused into fetal sheep has been studied. Uptake of glucose from the fetus by the placenta and transfer to the ewe, as well as placental metabolism of glucose to fructose and lactate have been quantified. About two-thirds of the glucose removed from the fetal circulation was taken up by placenta. Less than 15% of this passed back into the maternal circulation, the remainder was converted, at roughly equivalent rates, into lactate and fructose, most of which was transferred back to the fetus. It seems likely that little of this glucose is oxidised by the placenta. This data indicates that there are substrate cycles between the placenta and fetus, one possible function of which is to limit fetal glucose loss back to the mother; lactate and fructose have limited placental permeability. At uterine blood flow rates in the middle of the normal range net glucose uptake by the placenta from the maternal circulation was about 7-fold higher than that from the fetus. About 20% of this was transported to the fetus, 50% was oxidised and much of the remainder converted to lactate and transferred back to the ewe. Labelling patterns in fructose and lactate make it unlikely that this placental pool of glucose mixes freely with that derived from uptake from the fetus. Net movement of glucose across the placenta is markedly influenced by fluctuations in uterine blood flow over the normal range of 500-3000 ml/min. At low flow rates there is net output of glucose from the fetus to the placenta, and in some instances from the placenta to the ewe, i.e. there is evidence of net utero-placental production of glucose to the ewe separate from output by the fetus. There is a close linear relationship between uterine glucose supply (maternal arterial concentration x uterine blood flow) and net balance across the placenta. As uterine supply of glucose falls there is increased uptake by the placenta of glucose from the fetal circulation and corresponding enhanced recycling of fructose and lactate to the fetus. This production of fructose and lactate by the placenta may function to reduce glucose loss from the fetus to the ewe. Hence at high rates of placental uptake of glucose from the fetus placental production of lactate and particularly fructose may approach saturation and allow significant backflow of glucose from the fetus to the ewe. Under these conditions glucose uptake may in part sustain placental oxygen consumption.     

Maternal meal quality alters fetal rat brain serotonin concentrations

The quality of food eaten by pregnant animals may influence fetal neurotransmitter biosynthesis by altering the relative availability of precursor amino acids. Fetal brain concentrations of tryptophan and the neurotransmitter serotonin increase following the consumption of a carbohydrate-fat meal or after the injection of insulin in fasting animals; in contrast, the fetal concentrations of these compounds are reduced in animals whose mothers eat a meal containing casein protein or amino acids which compete with tryptophan for uptake from maternal blood into the placenta and fetus.     

Complex,coordinated and highly regulated changes in placental signaling and nutrient transport capacity in IUGR

The most common cause of intrauterine growth restriction (IUGR) in the developed world is placental insufficiency, a concept often used synonymously with reduced utero-placental and umbilical blood flows. However, placental insufficiency and IUGR are associated with complex, coordinated and highly regulated changes in placental signaling and nutrient transport including inhibition of insulin and mTOR signaling and down-regulation of specific amino acid transporters, Na⁺/K⁺-ATPase, the Na^+/H⁺-exchanger, folate and lactate transporters. In contrast, placental glucose transport capacity is unaltered and Ca²⁺-ATPase activity and the expression of proteins involved in placental lipid transport are increased in IUGR. These findings are not entirely consistent with the traditional view that the placenta is dysfunctional in IUGR, but rather suggest that the placenta adapts to reduce fetal growth in response to an inability of the mother to allocate resources to the fetus. This new model has implications for the understanding of the mechanisms underpinning IUGR and for the development of intervention strategies.     

Effect of restriction of placental growth on fetal and utero-placental metabolism

The effect of restriction of placental growth on the supply of glucose to the gravid uterus and fetus and on fetal and utero-placental metabolism of glucose and lactate was examined in this study. Endometrial caruncles were removed from 13 sheep (caruncle sheep) prior to mating, which restricted placental growth in the subsequent pregnancy. Half the fetuses of caruncle sheep were small or growth retarded, with the remainder normal in size. After insertion of vascular catheters at 110 days gestation, the caruncle sheep, together with 16 control sheep, were studied between 121 and 130 days of gestation. Glucose delivery to and consumption by the gravid uterus and its contents, both as a total and per kg of tissue mass, was significantly lower in caruncle ewes with small fetuses, although glucose extraction was similar to that in controls. Utero-placental glucose consumption was significantly lower in caruncle ewes carrying small fetuses compared to that in control ewes, both as a total and per kg of placenta. Small caruncle fetuses were hypoxaemic and hypoglycaemic and the lactate concentration in the common umbilical vein was significantly higher than in control sheep. Glucose delivery to and consumption by the fetus was significantly lower in normal-sized and in small caruncle fetuses compared to controls. Fetal glucose consumption per kg of fetus was similar in control and caruncle sheep. Fetal glucose extraction increased as fetal weight decreased. Utero-placental production of lactate was similar in control and caruncle ewes. However, uterine output of lactate decreased as placental weight fell. Utero-placental production of lactate per kg of placenta was significantly higher in caruncle ewes compared to controls and increased as oxygen content in blood from the fetal femoral artery decreased. Fetal lactate consumption per kg of fetus increased as the concentration of lactate in blood from the common umbilical vein increased. It is concluded that intrauterine growth retardation due to restriction of placental growth is associated with a reduced supply of glucose to both the pregnant uterus and fetus and a redistribution of glucose therein to the fetus, both directly as glucose and indirectly as lactate. This reflects the disproportionate maintenance of fetal weight relative to that of the placenta, reduced utero-placental consumption of glucose per kg of placenta, conversion of a greater proportion of that glucose or other substrate(s) to lactate by the placenta and an increase in the fraction of the lactate produced by utero-placental tissues that is secreted into the fetal circulation.     

Improving amino acid nutrition to prevent intrauterine growth restriction in mammals

Intrauterine growth restriction (IUGR) is one of the most common concerns in human obstetrics and domestic animal production. It is usually caused by placental insufficiency, which decreases fetal uptake of nutrients (especially amino acids) from the placenta. Amino acids are not only building blocks for protein but also key regulators of metabolic pathways in fetoplacental development. The enhanced demands of amino acids by the developing conceptus must be met via active transport systems across the placenta as normal pregnancy advances. Growing evidence indicates that IUGR is associated with a reduction in placental amino acid transport capacity and metabolic pathways within the embryonic/fetal development. The positive relationships between amino acid concentrations in circulating maternal blood and placental amino acid transport into fetus encourage designing new therapies to prevent or treat IUGR by enhancing amino acid availability in maternal diets or maternal circulation. Despite the positive effects of available dietary interventions, nutritional therapy for IUGR is still in its infancy. Based on understanding of the underlying mechanisms whereby amino acids promote fetal growth and of their dietary requirements by IUGR, supplementation with functional amino acids (e.g., arginine and glutamine) hold great promise for preventing fetal growth restriction and improving health and growth of IUGR offspring.     

Maternal Magnesium Restriction Elevates Glucocorticoid Stress and Inflammation in the Placenta and Fetus of WNIN Rat Dams

Magnesium plays a major role in many vital functions in the body. We reported earlier that maternal magnesium restriction altered body composition, fat metabolism, and insulin resistance in WNIN rat offspring and was associated with increased glucocorticoid stress in the offspring in their later life. We hypothesize that increased glucocorticoid stress and inflammation which originate in Mg restricted rat dams is transmitted through placenta to the fetus and underlie the metabolic disturbances in the later life of the offspring. Female weanling WNIN rats received ad libitum, a control diet (MgC) or the same with 62% restriction of Mg (MgR) for 3 months, and their plasma magnesium, inflammatory cytokines, and corticosterone were determined (n = 6 per group) before mating. Following mating with control males, placentae, and fetuses were collected on gestational day 15 (GD 15) from MgC and MgR dams (eight dams from each group and three samples from each dam) and used to determine the levels of inflammatory cytokines, corticosterone, and expression of relevant genes. MgR placentae and fetuses had higher (than MgC) levels of corticosterone and proinflammatory cytokines. Expression of Hsd11b1 was increased (sixfold, p < 0.05), while that of Hsd11b2 was decreased (0.4-fold, p < 0.05) in MgR (than MgC) placenta, whereas expression of Hsd11b1was increased (3.4-fold, p < 0.05) in MgR fetus. Chronic dietary magnesium restriction in WNIN female rats increased their levels of corticosterone, leptin, and proinflammatory cytokines which appeared to be transmitted through placenta to the fetus and could thus be associated with increased stress, altered body composition, fat metabolism, and insulin resistance in the later life of the offspring.     

血管紧张素AT1受体抗体阳性孕鼠后代高盐饮食后血管功能障碍

血管紧张素AT1受体抗体(AT1-Ab)可损伤胎盘发育,进而导致胎儿宫内生长受限(intrauterine growth restriction,IUGR).根据胎儿源性成人疾病学说,IUGR会明显增加成人后患心血管疾病的几率.本研究旨在观察AT1-Ab阳性孕鼠后代生长至成年后血管功能有无异常.24只雌性Wistar大...     

Overexpression of Endogenous Anti-Oxidants with Selenium Supplementation Protects Trophoblast Cells from Reactive Oxygen Species-Induced Apoptosis in a Bcl-2-Dependent Manner

The human placenta provides life support for the developing foetus, and a healthy placenta is a prerequisite to a healthy start to life. Placental tissue is subject to oxidative stress which can lead to pathological conditions of pregnancy such as preeclampsia, preterm labour and intrauterine growth restriction. Up-regulation of endogenous anti-oxidants may alleviate placental oxidative stress and provide a therapy for these complications of pregnancy. In this study, selenium supplementation, as inorganic sodium selenite (NaSel) or organic selenomethionine (SeMet), was used to increase the protein production and cellular activity of the important redox active proteins glutathione peroxidase (GPx) and thioredoxin reductase (Thx-Red). Placental trophoblast cell lines, BeWo, JEG-3 and Swan-71, were cultured in various concentrations of NaSel or SeMet for 24 h and cell extracts prepared for western blots and enzyme assays. Rotenone and antimycin were used to stimulate mitochondrial reactive oxygen species (ROS) production and induce apoptosis. Trophoblast cells supplemented with 100 nM NaSel and 500 nM SeMet exhibited significantly enhanced expression and activity of both GPx and Thx-Red. Antimycin and rotenone were found to generate ROS when measured by 2′,7′-dichlorofluorescein diacetate (DCFDA) assay, and selenium supplementation was shown to reduce ROS production in a dose-dependent manner. Rotenone, 100 μM treatment for 4 h, caused trophoblast cell apoptosis as evidenced by increased Annexin V binding and decreased expression of Bcl-2. In both assays of apoptosis, selenium supplementation was able to prevent apoptosis, preserve Bcl-2 expression and protect trophoblast cells from mitochondrial oxidative stress. This data suggests that selenoproteins such as GPx and Thx-Red have an important role in protecting trophoblast cells from mitochondrial oxidative stress and that selenium supplementation may be important in treating some placental pathologies.     

Differential expression of placental 11β-hydroxysteroid dehydrogenases in pregnant women with diet-treated gestational diabetes mellitus

Fetal exposure to excess glucocorticoid is one of the critical factors for the fetal origins of adult diseases. However, the mechanism of the local regulation of glucocorticoid activity in the human placenta of pregnancies complicated with gestational diabetes mellitus (GDM) has not been fully understood. We investigated placental 11β-hydroxysteroid dehydrogenases (11β-HSDs) expression, and analyzed their relationship with cortisol levels in maternal and umbilical vein. Pregnant women with GDM after diet intervention (n=23) or normal glucose tolerance (NGT, n=22) were studied at the community-based hospital. We collected maternal and umbilical venous cord blood and placental tissues from both groups. Explanted placentas from NGT were cultured with palmitic acid, dexamethasone, insulin or their mixture for 24-h. We examined plasma cortisol, cortisone to cortisol ratio, insulin, the homeostasis model assessment of insulin resistance index (HOMA-IR) and the insulin secretion index. Quantitative real-time PCR, Western blot and immunohistochemical assay were applied for the measurement of 11β-HSD1 and 11β-HSD2 mRNA and protein. GDM had higher maternal cortisol levels, HOMA-IR, insulin secretion index and higher cortisone to cortisol ratio in umbilical vein. No significant change in cortisol levels in umbilical vein and newborn weight was found. GDM placental 11β-HSD1 levels decreased while 11β-HSD2 increased. Treatment of placenta explants from NGT with palmitic acid, dexamethasone, insulin or their combination resulted in a significant drop of 11β-HSD1 and increase in 11β-HSD2. Differential expression of 11β-HSDs in diet-treated GDM placenta provides a protective mechanism for the fetus throughout the adverse environment of pregnancy by limiting excessive exposure of the fetus to glucocorticoid.     

A murine model for the assessment of placental and fetal development in teratogenicity studies

During normal pregnancy in the mouse, maternal serum levels of the analogues to human schwangerschaftsprotein-1 and alpha-fetoprotein correlate significantly with the growth of the placenta and fetus respectively. This relationship has been utilized in the analysis of the effect of sodium selenite on placental and fetal growth in mice. Moderate doses of sodium selenite did not affect the growth of the placenta and fetus significantly, whereas high doses of selenite resulted in a large percentage of abortions. The protein markers were found to be useful in the prediction of placental and fetal growth, and they are suggested to be of general use in the study of the impact of teratogenic substances, since they reflect the status of the fetoplacental mass during gestation.     

Fetal insulin and placental 3-O-methyl glucose clearance in near-term sheep

It is difficult, if not impossible, to measure the placental transfer of glucose directly because of placental glucose consumption and the low A-V glucose difference across the sheep placenta. We have approached the problem of quantifying placental hexose transfer by using a nonmetabolized glucose analogue (3-O-methyl glucose) which shares the glucose transport system. We have measured the clearance by using a multisample technique permitting least squares linear computing to avoid the errors implicit in the Fick principle. The placental clearance of 3-O-methyl glucose was measured in the control condition and after the administration of insulin to the fetal circulation. A glucose clamp technique was used to maintain constant transplacental glucose concentrations throughout the duration of the experiment. A control series was performed in which the only intervention was the infusion of normal saline. In these experiments the maternal and fetal glucose concentrations remained constant as did the volume of distribution of 3-O-methyl glucose in the fetus. The maternal insulin concentration remained constant and fetal insulin concentration changed from 11 +/- 2 microU/ml to 355 +/- 51 microU/ml (P less than 0.01). In the face of this large increase in fetal plasma insulin, there was no change in the placental clearance of 3-O-methyl glucose. In the control condition the clearance was 14.1 +/- 1.0 ml/min per kg and this was 13.8 +/- 1.0 ml/min per kg in the high insulin condition. Fetal insulin may change placental glucose flux by decreasing fetal plasma glucose concentrations but does not do so by changing the activity of the glucose transport system.     

Paternal obesity induces epigenetic aberrations and gene expression changes in placenta and fetus

Paternal epigenome regulates placental and fetal growth. However, the effect of paternal obesity on placenta and its subsequent effect on the fetus via sperm remains unknown. We previously discovered abnormal methylation of imprinted genes involved in placental and fetal development in the spermatozoa of obese rats. In the present study, elaborate epigenetic characterization of sperm, placenta, and fetus was performed. For 16 weeks, male rats were fed either control or a high-fat diet. Following mating studies, sperm, placenta, and fetal tissue were collected. Significant changes were observed in placental weights, morphology, and cell populations. Methylation status of imprinted genes—Igf2, Peg3, Cdkn1c, and Gnas in spermatozoa, correlated with their expression in the placenta and fetus. Placental DNA methylating enzymes and 5-methylCytosine levels increased. Furthermore, in spermatozoa, DNA methylation of a few genes involved in pathways associated with placental endocrine function—gonadotropin-releasing hormone, prolactin, estrogen, and vascular endothelial growth factor, correlated with their expression in placenta and fetus. Changes in histone-modifying enzymes were also observed in the placenta. Histone marks H3K4me3, H3K9me3, and H4ac were downregulated, while H3K27me3 and H3ac were upregulated in placentas derived from obese male rats. This study shows that obesity-related changes in sperm methylome translate into abnormal expression in the F1-placenta fathered by the obese male, presumably affecting placental and fetal development.     

Differential expression of glucose transporters in rabbit placenta: effect of hypercholesterolemia in dams

Low birth weight is observed in rabbit offspring when maternal hypercholesterolemia is induced during gestation, but the related etiology is still unknown. Glucose is one of the most important substances during fetal development, and defect in glucose supply to fetus was related to pathophysiological mechanisms in intrauterine growth restriction. Thus, the aim of this work was to evaluate the impact of maternal hypercholesterolemia during rabbit gestation on the glucose metabolism and the routing of glucose transporters (SLC2 and SLC5 [previously known as GLUT and SGLT]) in placenta. In this study, maternal and offspring serum levels of glucose and insulin were evaluated for control and hypercholesterolemic groups, and the mRNA and protein expressions of placental SLCs were quantified by real-time RT-PCR and Western immunoblot, respectively. Our data demonstrate that maternal hypercholesterolemia during gestation: 1) induces offspring hypoglycemia; 2) does not modify the genetic and protein expressions of SLC2A1 and SLC2A4 (previously GLUT1 and GLUT4) in total placental extract; 3) downregulates the placental SLC5A1 (previously SGLT1) protein expression without affecting its mRNA levels; 4) impairs the translocation of SLC2A1 but not SLC2A4 from cytoplasmatic pool to the cell membrane surface. Then we assume that reduction of offspring birth weight in presence of maternal hypercholesterolemia may be related to the offspring's hypoglycemia and the reduction of the cell surface expression of placental SLC2A1.     

High and Low Protein∶ Carbohydrate Dietary Ratios during Gestation Alter Maternal-Fetal Cortisol Regulation in Pigs

Imbalanced maternal nutrition during gestation can cause alterations of the hypothalamic-pituitary-adrenal (HPA) system in offspring. The present study investigated the effects of maternal low- and high-protein diets during gestation in pigs on the maternal-fetal HPA regulation and expression of the glucocorticoid receptor (GR), mineralocorticoid receptor (MR), 11β-hydroxysteroid dehydrogenase 1 and 2 (11β-HSD1 and 11β-HSD2) and c-fos mRNAs in the placenta and fetal brain. Twenty-seven German Landrace sows were fed diets with high (HP, 30%), low (LP, 6.5%) or adequate (AP, 12.1%) protein levels made isoenergetic by varying the carbohydrate levels. On gestational day 94, fetuses were recovered under general anesthesia for the collection of blood, brain and placenta samples. The LP diet in sows increased salivary cortisol levels during gestation compared to the HP and AP sows and caused an increase of placental GR and c-fos mRNA expression. However, the diurnal rhythm of plasma cortisol was disturbed in both LP and HP sows. Total plasma cortisol concentrations in the umbilical cord vessels were elevated in fetuses from HP sows, whereas corticosteroid-binding globulin levels were decreased in LP fetuses. In the hypothalamus, LP fetuses displayed an enhanced mRNA expression of 11β-HSD1 and a reduced expression of c-fos. Additionally, the 11β-HSD2 mRNA expression was decreased in both LP and HP fetuses. The present results suggest that both low and high protein∶carbohydrate dietary ratios during gestation may alter the expression of genes encoding key determinants of glucocorticoid hormone action in the fetus with potential long-lasting consequences for stress adaptation and health.     

Inhibition of placental ornithine decarboxylase by DL-alpha-difluoro-methyl ornithine causes fetal growth restriction in rat

The roles of polyamines in intrauterine growth restriction (IUGR) is studied. The DL-alpha-difluoromethyl ornithine (DFMO), an irreversible inhibitor of ornithine decarboxylase (ODC) which is a rate limiting enzyme of polyamine synthesis was administrated to pregnant rats so that we obtained rat fetuses with IUGR. The changes of maternal nutrition, damage of the placenta, and the direct effect of DFMO on the fetus were examined in this IUGR model. Administration of DFMO did not induced changes of maternal nutrition except for triglyceride and the fetal metabolic state. But the placental weight, ODC activity, and DNA in the placenta were decreased significantly. The ODC activity in the total placenta decreased to less than 10% of that of the control. Depression of ODC activity in the placenta may be the major cause of IUGR induced by DFMO administration, and polyamines play important roles to carry pregnancy.