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.     

Human placental transthyretin in fetal growth restriction in combination with preeclampsia and the HELLP syndrome

Fetal growth restriction is a serious, still poorly understood pregnancy-related pathology often associated with preeclampsia. Recent studies speculate on the role of human transthyretin, a carrier protein for thyroxin and retinol binding protein, in the etiology of both pregnancy pathologies. Objective was to investigate the localization and abundance of transthyretin (TTR) in placentas of pregnancies suffering from fetal growth restriction with and without preeclampsia and HELLP. This was a retrospective case control study on human paraffin-embedded placentas from pregnancies with a gestational age at delivery between the 24th and 34th week of gestation. 16 placentas were included in this study, 11 cases and 5 from normotensive pregnancies as controls. Cases were divided into three groups: four from early onset idiopathic intrauterine growth restriction (IUGR), four from early-onset severe preeclampsia (PE), and three from early-onset IUGR with preeclampsia plus HELLP syndrome. Distribution and abundance of TTR were investigated by means of immunohistochemistry. Semi quantitative analysis of TTR staining of placental sections revealed that TTR was mostly expressed in the villous trophoblast covering placental villi. Only weak staining of TTR in villous stroma could be detected. The comparison of placentas revealed that in pure IUGR and severe PE there is a much stronger TTR reactivity compared to controls and cases with IUGR?+?PE?+?HELLP. Concluding, the study showed that TTR is dysregulated in cases of IUGR and severe early onset preeclampsia. Interestingly, TTR expression is not affected in cases with HELLP syndrome that reveal the same staining intensities as age-matched controls.     

Uteroplacental restriction in the rat impairs fetal growth in association with alterations in placental growth factors including PTHrP

During pregnancy, parathyroid hormone-related protein (PTHrP) is one of many growth factors that play important roles to promote fetal growth and development, including stimulation of placental calcium transport. Angiotensin II, acting through the AT(1a) receptor, is also known to promote placental growth. We examined the effects of bilateral uterine artery and vein ligation (restriction), which mimics placental insufficiency in humans, on growth, intrauterine PTHrP, placental AT(1a), and pup calcium. Growth restriction was surgically induced on day 18 of pregnancy in Wistar-Kyoto female rats by uterine vessel ligation. Uteroplacental insufficiency reduced fetal body weight by 15% and litter size (P < 0.001) compared with the control rats with no effect on placental weight or amniotic fluid volume. Uteroplacental insufficiency reduced placental PTHrP content by 46%, with increases in PTHrP (by 2.6-fold), parathyroid hormone (PTH)/PTHrP receptor (by 11.6-fold), and AT(1a) (by 1.7-fold) relative mRNA in placenta following restriction compared with results in control (P < 0.05). There were no alterations in uterine PTHrP and PTH/PTHrP receptor mRNA expression. Maternal and fetal plasma PTHrP and calcium concentrations were unchanged. Although fetal total body calcium was not altered, placental restriction altered perinatal calcium homeostasis, as evidenced by lower pup total body calcium after birth (P < 0.05). The increased uterine and amniotic fluid PTHrP (P < 0.05) may be an attempt to compensate for the induced impaired placental function. The present study demonstrates that uteroplacental insufficiency alters intrauterine PTHrP, placental AT(1a) expression, and perinatal calcium in association with a reduction in fetal growth. Uteroplacental insufficiency may provide an important model for exploring the early origins of adult diseases.     

Ultrasound evidence of early fetal growth restriction after maternal malaria infection

Background

Intermittent preventive treatment (IPT), the main strategy to prevent malaria and reduce anaemia and low birthweight, focuses on the second half of pregnancy. However, intrauterine growth restriction may occur earlier in pregnancy. The aim of this study was to measure the effects of malaria in the first half of pregnancy by comparing the fetal biparietal diameter (BPD) of infected and uninfected women whose pregnancies had been accurately dated by crown rump length (CRL) before 14 weeks of gestation.

Methodology/Principal Findings

In 3,779 women living on the Thai-Myanmar border who delivered a normal singleton live born baby between 2001–10 and who had gestational age estimated by CRL measurement <14 weeks, the observed and expected BPD z-scores (<24 weeks) in pregnancies that were (n = 336) and were not (n = 3,443) complicated by malaria between the two scans were compared. The mean (standard deviation) fetal BPD z-scores in women with Plasmodium (P) falciparum and/or P.vivax malaria infections were significantly lower than in non-infected pregnancies; −0.57 (1.13) versus −0.10 (1.17), p<0.001. Even a single or an asymptomatic malaria episode resulted in a significantly lower z-score. Fetal female sex (p<0.001) and low body mass index (p = 0.01) were also independently associated with a smaller BPD in multivariate analysis.

Conclusions/Significance

Despite early treatment in all positive women, one or more (a)symptomatic P.falciparum or P.vivax malaria infections in the first half of pregnancy result in a smaller than expected mid-trimester fetal head diameter. Strategies to prevent malaria in pregnancy should include early pregnancy.     

Protein restriction in early pregnancy alters fetal and placental growth and allantoic fluid proteins in swine

This study was designed to determine the impact of protein malnutrition during early pregnancy on fetal and placental growth and on the protein synthesis capacity of placental and endometrial tissues. Twelve crossbred sows received 1.8 kg/d of a control (13% protein) or protein-restricted (0.5% protein) diet from the day of breeding to Day 63 of pregnancy, when dissections were performed on each conceptus unit. The de novo protein synthetic rate of placental and endometrial explants was measured using (35)S-methionine. These proteins and the proteins from amniotic and allantoic fluids were separated by polyacrylamide gel electrophoresis. Placental weight was significantly reduced in the sows fed the restricted diet, with a tendency for decreased fetal weight as well. No differences were found due to dietary treatment in de novo protein synthesis or in the electrophoretic patterns of secreted proteins of the placenta or endometrium. The apparent quantity of 3 proteins in the allantoic fluid of the restricted diet fetuses decreased, while 1 protein increased in comparison with that of the control fetuses. These data suggest that protein malnutrition in early pregnancy decreases placental growth, thereby decreasing both fetal growth and the opportunity for compensatory growth upon nutritional rehabilitation.     

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.     

Increased insulin sensitivity and maintenance of glucose utilization rates in fetal sheep with placental insufficiency and intrauterine growth restriction

In this study we determined body weight-specific fetal (umbilical) glucose uptake (UGU), utilization (GUR), and production rates (GPR) and insulin action in intrauterine growth-restricted (IUGR) fetal sheep. During basal conditions, UGU from the placenta was 33% lower in IUGR fetuses, but GUR was not different between IUGR and control fetuses. The difference between glucose utilization and UGU rates in the IUGR fetuses demonstrated the presence and rate of fetal GPR (41% of GUR). The mRNA concentrations of the gluconeogenic enzymes glucose-6-phophatase and PEPCK were higher in the livers of IUGR fetuses, perhaps in response to CREB activation, as phosphorylated CREB/total CREB was increased 4.2-fold. A hyperglycemic clamp resulted in similar rates of glucose uptake and utilization in IUGR and control fetuses. The nearly identical GURs in IUGR and control fetuses at both basal and high glucose concentrations occurred at mean plasma insulin concentrations in the IUGR fetuses that were approximately 70% lower than controls, indicating increased insulin sensitivity. Furthermore, under basal conditions, hepatic glycogen content was similar, skeletal muscle glycogen was increased 2.2-fold, the fraction of fetal GUR that was oxidized was 32% lower, and GLUT1 and GLUT4 concentrations in liver and skeletal muscle were the same in IUGR fetuses compared with controls. These results indicate that insulin-responsive fetal tissues (liver and skeletal muscle) adapt to the hypoglycemic-hypoinsulinemic IUGR environment with mechanisms that promote glucose utilization, particularly for glucose storage, including increased insulin action, glucose production, shunting of glucose utilization to glycogen production, and maintenance of glucose transporter concentrations.     

Effect of iron deficiency on placental cytokine expression and fetal growth in the pregnant rat.

Iron deficiency anemia is the most common nutritional disorder in the world. Anemia is especially serious during pregnancy, with deleterious consequences for both the mother and her developing fetus. We have developed a model to investigate the mechanisms whereby fetal growth and development are affected by maternal anemia. Weanling rats were fed a control or iron-deficient diet before and throughout pregnancy and were killed at Day 21. Dams on the deficient diet had lower hematocrits, serum iron concentrations, and liver iron levels. Similar results were recorded in the fetus, except that the degree of deficiency was markedly less, indicating compensation by the placenta. No effect was observed on maternal weight or the number and viability of fetuses. The fetuses from iron-deficient dams, however, were smaller than controls, with higher placental:fetal ratios and relatively smaller livers. Iron deficiency increased levels of tumor necrosis factor alpha (TNFalpha) only in the trophoblast giant cells of the placenta. In contrast, levels of type 1 TNFalpha receptor increased significantly in giant cells, labyrinth, cytotrophoblast, and fetal vessels. Leptin levels increased significantly in labyrinth and marginally (P = 0.054) in trophoblast giant cells. No change was observed in leptin receptor levels in any region of the placentas from iron-deficient dams. The data show that iron deficiency not only has direct effects on iron levels and metabolism but also on other regulators of growth and development, such as placental cytokines, and that these changes may, in part at least, explain the deleterious consequences of maternal iron deficiency during pregnancy.     

Supplementation with high-dose cholecalciferol throughout pregnancy induces fetal growth restriction through inhibiting placental proliferation and trophoblast epithelial-mesenchymal transition

Vitamin D deficiency has been associated with adverse pregnant outcomes. Several studies investigated the effects of maternal vitamin D3 supplementation on fetal development with inconsistent results. The aim of this study was to investigate the effects of maternal supplementation with different doses of vitamin D3 on fetal development. Pregnant mice were administered with different doses of cholecalciferol (0, 2,000, 10,000, 40,000 IU/kg/day) by gavage throughout pregnancy. Fetal weight and crown-rump length were measured. Placental proliferation and mesenchymal characteristics were detected. HTR-8/SVneo cells were incubated in the absence or presence of calcitriol (500 nmol/L) to evaluate the effects of active vitamin D3 on migration and invasion of human trophoblast cells. Although a low dose of cholecalciferol was safe, fetal weight and crown-rump length were decreased in dams treated with high-dose cholecalciferol throughout pregnancy. Placental weight and labyrinth thickness were reduced in mice administered with high-dose cholecalciferol. An obvious calcification was observed in placentae of mice administered with high-dose cholecalciferol. Ki67-positive cells, a marker of placental proliferation, were reduced in mice administered with high-dose cholecalciferol. N-cadherin and vimentin, two mesenchymal markers, were decreased in cholecalciferol-treated mouse placentae and calcitriol-treated human trophoblast cells. MMP-2 and MMP-9, two matrix metalloproteinases, were downregulated in cholecalciferol-treated mouse placentae and calcitriol-treated human trophoblast cells. In addition, trophoblast migration and invasion were suppressed by calcitriol. Supplementation with high-dose cholecalciferol induces fetal growth restriction partially through inhibiting placental proliferation and trophoblast epithelial-mesenchymal transition.     

Differential levels of soluble endoglin (CD105) in myeloid malignancies

Angiogenesis contributes to disease progression in solid and hematopoietic malignancies, and endoglin (CD105), a component of the transforming growth factor (TGF)-beta receptor complex, is a powerful marker of neovascularization. Elevated amounts of soluble CD105 (sCD105) have been recently identified in selected solid tumors but no data are available on sCD105 in hematopoietic malignancies. Therefore, levels of sCD105 were investigated in sera of patients with acute myeloid leukemia (AML) (n = 10) or chronic myeloproliferative disorders (CMD) (n = 28), and correlated with those of soluble TGF-beta(1) (sTGF-beta(1)). Dot blot assay detected higher amounts of sCD105 (P < 0.05) both in AML (4.34 +/- 2.62 OD/mm(2)) and in CMD (3.71 +/- 2.09 OD/mm(2)) patients than in healthy subjects (n = 14, 2.38 +/- 1.18 OD/mm(2)). Instead, enzyme-linked immunosorbent assay (ELISA) identified (P < 0.05) lower and higher levels of sTGF-beta(1) in AML (32,017 +/- 1,900 pg/ml) and CMD (60,700 +/- 19,200 pg/ml) patients, respectively, compared to healthy individuals (n = 11, 47,173 +/- 5,443 pg/ml). In essential thrombocythemia (ET) patients with thrombotic episodes, levels of sCD105 were lower (P < 0.05) compared to patients without thrombotic complications, and inversely correlated with those of sTGF-beta(1) (r = 0.94). Conversely, amounts of sCD105 directly correlated with levels of sTGF-beta(1) (r = 0.74) in ET patients without thrombotic events. Our results show that high levels of sCD105 are present in myeloid malignancies that are characterized by a high cellular proliferation rate, and suggest that an altered balance between sCD105 and sTGF-beta(1) might favor disease progression and clinical complications.     

Relationship among placental cadmium, lead, zinc, and copper levels in smoking pregnant women

Previous studies on Cd-exposed pregnant animals have reported a Cd-Zn interaction that result in increased placental Cd levels and decreased placental Zn transport. In this study, placental Cd, Pb, Cu, and Zn status in pregnant women exposed to Cd and Pb through cigarette smoke was investigated. Placental tissues obtained from 30 nonsmokers (controls), 70 passive smokers, and 90 smokers were analyzed for Cu and Zn levels using an atomic absorption spectrophotometer and for Pb and Cd levels using an EG&G PARC Model 303A hanging mercury drop electrode. The result showed that whereas the placental Cd and Pb levels in smokers were higher that those of nonsmokers, Cu and zinc levels were lower in nonsmokers. These results imply that smoking during pregnancy could be harmful for both the mother and the fetus.     

Maternal nutrient restriction during placental growth,programming of fetal adiposity and juvenile blood pressure control

Epidemiological and experimental studies have demonstrated that maternal undernutrition during pregnancy is associated with abnormal placental growth. In sheep, maternal nutrient restriction over the period of rapid placental growth (30-80 days) restricts placentome growth. Then following adequate nutrition up to term (147 days), placental mass is greater in association with a higher total abundance of the predominant placental glucose transporter-1. The resulting lambs are larger at birth, have heavier kidneys with an increased expression of the glucocorticoid-responsive type 1 angiotensin II receptor. Near to term, these fetuses possess more adipose tissue, the endocrine sensitivity of which is markedly enhanced. For example, the abundance of mRNA for 11beta-hydroxysteroid dehydrogenase type 1, which catalyses the conversion of cortisone to bio-active cortisol is increased. This is associated with a higher abundance of both leptin and glucocorticoid receptor mRNA. At 6 months of age, the juvenile offspring of nutrient restricted ewes have lower resting blood pressure that was positively correlated with plasma cortisol concentration, suggesting their blood pressure could be more strongly driven by circulating cortisol. These offspring also exhibited a greater pressor response to vasoconstrictor challenges, but showed no difference in vasodilatory response. At this age, the kidney weight was similar between groups, but the abundance of cytochrome c in kidney mitochondria was enhanced in lambs born to nutrient restricted ewes that could indicate increased mitochondrial activity. Reduced maternal nutrition during the period of rapid placental growth may therefore contribute to hypertension in later life through physiological and vascular adaptations during fetal life.     

Circulating levels of matrix proteases and their inhibitors in pregnant women with and without a history of recurrent pregnancy loss

Background  

We have recently shown that serum relaxin-2 levels are attenuated in women with a history of recurrent pregnancy loss (RPL). We sought to determine whether a history of RPL is also associated with changes in serum matrix metalloproteases (MMPs) and tissue inhibitors of matrix metalloproteases (TIMP) -1 and -2.     

Systematic review and meta-analysis: rapid diagnostic tests versus placental histology, microscopy and PCR for malaria in pregnant women

Background

To prepare field sites for malaria vaccine trials, it is important to determine baseline antibody and T cell responses to candidate malaria vaccine antigens. Assessing T cell responses is especially challenging, given genetic restriction, low responses observed in endemic areas, their variability over time, potential suppression by parasitaemia and the intrinsic variability of the assays.

Methods

In Part A of this study, antibody titres were measured in adults from urban and rural communities in Ghana to recombinant Plasmodium falciparum CSP, SSP2/TRAP, LSA1, EXP1, MSP1, MSP3 and EBA175 by ELISA, and to sporozoites and infected erythrocytes by IFA. Positive ELISA responses were determined using two methods. T cell responses to defined CD8 or CD4 T cell epitopes from CSP, SSP2/TRAP, LSA1 and EXP1 were measured by ex vivo IFN-γ ELISpot assays using HLA-matched Class I- and DR-restricted synthetic peptides. In Part B, the reproducibility of the ELISpot assay to CSP and AMA1 was measured by repeating assays of individual samples using peptide pools and low, medium or high stringency criteria for defining positive responses, and by comparing samples collected two weeks apart.

Results

In Part A, positive antibody responses varied widely from 17%-100%, according to the antigen and statistical method, with blood stage antigens showing more frequent and higher magnitude responses. ELISA titres were higher in rural subjects, while IFA titres and the frequencies and magnitudes of ex vivo ELISpot activities were similar in both communities. DR-restricted peptides showed stronger responses than Class I-restricted peptides. In Part B, the most stringent statistical criteria gave the fewest, and the least stringent the most positive responses, with reproducibility slightly higher using the least stringent method when assays were repeated. Results varied significantly between the two-week time-points for many participants.

Conclusions

All participants were positive for at least one malaria protein by ELISA, with results dependent on the criteria for positivity. Likewise, ELISpot responses varied among participants, but were relatively reproducible by the three methods tested, especially the least stringent, when assays were repeated. However, results often differed between samples taken two weeks apart, indicating significant biological variability over short intervals.     

Meiotic origin of trisomy in confined placental mosaicism is correlated with presence of fetal uniparental disomy,high levels of trisomy in trophoblast,and increased risk of fetal intrauterine growth restriction.

Molecular studies were performed on 101 cases of confined placental mosaicism (CPM) involving autosomal trisomy. The origin of the trisomic cell line was determined in 54 cases (from 51 pregnancies), 47 of which were also analyzed for the presence of uniparental disomy (UPD) in the disomic cell line. An additional 47 cases were analyzed for parental origin in the disomic cell line only. A somatic (postmeiotic) origin of the trisomy was observed in 22 cases and included the majority of cases with CPM for trisomy 2, 7, 8, 10, and 12. Most cases of CPM involving trisomy 9, 16, and 22 were determined to be meiotic. Fetal maternal UPD was found in 17 of 94 informative CPM cases, involving trisomy 2 (1 case), 7 (1 case), 16 (13 cases), and 22 (2 cases). The placental trisomy was of meiotic origin in all 17 cases associated with fetal UPD (P = .00005). A meiotic origin also correlated with the levels of trisomy in cultured chorionic villi samples (CVS) (P = .0002) and trophoblast (P = .00005). Abnormal pregnancy outcome (usually IUGR) correlated with meiotic origin (P = .0003), the presence of fetal UPD (P = 4 x 10(-7)), and the level of trisomy in trophoblast (P = 3 x 10(-7)) but not with the level of trisomy in CVS or term chorion. The good fit of somatic errors with the expected results could have been observed only if few true meiotic errors were misclassified by these methods as a somatic error. These data indicate that molecular determination of origin is a useful predictor of pregnancy outcome, whereas the level of trisomy observed in cultured CVS is not. In addition, UPD for some chromosomes may affect prenatal, but not postnatal, development, possibly indicating that imprinting effects for these chromosomes are confined to placental tissues.     

Effect of restriction of placental growth on oxygen delivery to and consumption by the pregnant uterus and fetus

Endometrial caruncles were excised from 13 sheep (caruncle sheep) before pregnancy to restrict placental growth. In subsequent pregnancies, half the caruncle fetuses were growth retarded or small (weight more than 2 SD below mean weight for control fetuses) with the remainder, normal-sized (weight within 2 SD of mean weight for control fetuses). The caruncle and 16 control sheep, each with indwelling vascular catheters, were studied between 121 and 130 days of pregnancy. Oxygen delivery to and consumption by the pregnant uterus in caruncle sheep with small fetuses was significantly reduced compared to controls while oxygen extraction was significantly increased. Oxygen tension (P02) and content in the common umbilical vein and in the descending aorta were significantly lower in small caruncle fetuses compared to controls but only P02 was lower in normal-sized caruncle fetuses. Oxygen delivery to, and consumption by, the fetus was significantly reduced in normal-sized and in small caruncle sheep compared to controls while oxygen extraction was increased in small caruncle sheep. Utero-placental oxygen consumption was significantly lower in caruncle sheep with small fetuses compared to that in controls. Despite these changes, oxygen consumption by the gravid uterus and fetus, per kg of tissue mass, was similar in both groups of caruncle and in control sheep. Utero-placental oxygen consumption per kg of utero-placental mass in caruncle sheep with small fetuses was not significantly different to that in sheep with normal-sized caruncle or control fetuses, although it averaged only 25% of that in controls. It is concluded that intrauterine growth retardation following restriction of placental growth is associated with a reduced supply of oxygen to both the pregnant uterus and fetus and a redistribution of oxygen to the fetus. This is due to the disproportionate maintenance of fetal growth relative to that of the placenta, since oxygen consumption by either, in terms of tissue mass, was not altered. Further, the greater uterine and fetal extraction of oxygen suggests that a smaller margin of safety may exist between supply and demand in intrauterine growth retardation.     

Chronic alterations in ovine maternal corticosteroid levels influence uterine blood flow and placental and fetal growth

Previous work from this laboratory demonstrated that the elevation of maternal plasma corticosteroid concentrations during pregnancy is important for the support of fetal development. Reducing ovine maternal plasma cortisol concentrations to nonpregnant levels stimulates homeostatic responses that defend fetal blood volume. The present study was designed to test the hypothesis that chronic decreases or increases in maternal plasma cortisol concentration alter uterine and placental blood flow and morphology. Three groups of pregnant ewes and their fetuses were chronically catheterized and studied: ewes infused with cortisol (1 mg.kg(-1).day(-1); high cortisol), ewes adrenalectomized and underreplaced with cortisol (0.5 mg.kg(-1).day(-1); low cortisol), and control ewes. The normal increment in uterine blood flow between 120 and 130 days was eliminated in the low-cortisol ewes; conversely, uterine blood flow was increased in the high-cortisol group compared with the control group. Fetal arterial blood pressure was increased in the high-cortisol group compared with controls, but there was no increase in fetal arterial pressure from 120 to 130 days of gestation in the low-cortisol group. The fetuses of both low-cortisol and high-cortisol groups had altered placental morphology, with increased proportions of type B placentomes, and overall reduced fetal placental blood flow. The rate of fetal somatic growth was impaired in both low-cortisol and high-cortisol groups compared with the fetuses in the intact group. The results of this study demonstrate that maternal plasma cortisol during pregnancy is an important contributor to the maternal environment supporting optimal conditions for fetal homeostasis and somatic growth.     

Altered downstream target gene expression of the placental Vitamin D receptor in human idiopathic fetal growth restriction

Fetal growth restriction (FGR) affects up to 5% of pregnancies and is associated with significant perinatal complications. Maternal deficiency of vitamin D, a secosteroid hormone, is common in FGR-affected pregnancies. We recently demonstrated that decreased expression of the vitamin D receptor (VDR) in idiopathic FGR placentae could impair trophoblast growth. As strict regulation of cell-cycle genes in trophoblast cells is critical for optimal feto-placental growth, we hypothesised that pathologically decreased placental VDR contributes to aberrant regulation of cell-cycle genes. The study aims were to (i) identify the downstream cell-cycle regulatory genes of VDR in trophoblast cells, and (ii) determine if expression was changed in cases of FGR. Targeted cell-cycle gene cDNA arrays were used to screen for downstream targets of VDR in VDR siRNA-transfected BeWo and HTR-8/SVneo trophoblast-derived cell lines, and in third trimester placentae from FGR and gestation-matched control pregnancies (n = 25 each). The six candidate genes identified were CDKN2A, CDKN2D, HDAC4, HDAC6, TGFB2 and TGFB3. TGFB3 was prioritised for further validation, as its expression is largely unknown in FGR. Significantly reduced mRNA and protein expression of TGFB3 was verified in FGR placentae and the BeWo and HTR-8/SVneo trophoblast cell lines, using real-time PCR and immunoblotting respectively. In summary, decreased placental VDR expression alters the expression of regulatory cell-cycle genes in FGR placentae. Aberrant regulation of cell-cycle genes in the placental trophoblast cells may constitute a mechanistic pathway by which decreased placental VDR reduces feto-placental growth.     

eNOS knockout mouse as a model of fetal growth restriction with an impaired uterine artery function and placental transport phenotype

Fetal growth restriction (FGR) is the inability of a fetus to reach its genetically predetermined growth potential. In the absence of a genetic anomaly or maternal undernutrition, FGR is attributable to "placental insufficiency": inappropriate maternal/fetal blood flow, reduced nutrient transport or morphological abnormalities of the placenta (e.g., altered barrier thickness). It is not known whether these diverse factors act singly, or in combination, having additive effects that may lead to greater FGR severity. We suggest that multiplicity of such dysfunction might underlie the diverse FGR phenotypes seen in humans. Pregnant endothelial nitric oxide synthase knockout (eNOS(-/-)) dams exhibit dysregulated vascular adaptations to pregnancy, and eNOS(-/-) fetuses of such dams display FGR. We investigated the hypothesis that both altered vascular function and placental nutrient transport contribute to the FGR phenotype. eNOS(-/-) dams were hypertensive prior to and during pregnancy and at embryonic day (E) 18.5 were proteinuric. Isolated uterine artery constriction was significantly increased, and endothelium-dependent relaxation significantly reduced, compared with wild-type (WT) mice. eNOS(-/-) fetal weight and abdominal circumference were significantly reduced compared with WT. Unidirectional maternofetal (14)C-methylaminoisobutyric acid (MeAIB) clearance and sodium-dependent (14)C-MeAIB uptake into mouse placental vesicles were both significantly lower in eNOS(-/-) fetuses, indicating diminished placental nutrient transport. eNOS(-/-) mouse placentas demonstrated increased hypoxia at E17.5, with elevated superoxide compared with WT. We propose that aberrant uterine artery reactivity in eNOS(-/-) mice promotes placental hypoxia with free radical formation, reducing placental nutrient transport capacity and fetal growth. We further postulate that this mouse model demonstrates "uteroplacental hypoxia," providing a new framework for understanding the etiology of FGR in human pregnancy.     

Indices of oxidative stress in pregnancy with fetal growth restriction

Intrauterine fetal growth restriction (IUGR), the main cause of premature delivery and fetal mortality, has been suggested to involve oxidative stress. We found elevated values of indices of oxidative stress in the blood serum of pregnant women with IUGR: increased levels of malondialdehyde and 4-hydroxyalkenals, decreased activity of alpha-1-antitrypsin and decreased total antioxidant capacity of the serum, with respect to healthy pregnancy. Twenty day treatment with 3 g of l-arginine and 75 mg of acetylsalicylic acid daily resulted in a decrease of the level of lipid peroxidation products and augmentation of alpha-1-antitrypsin activity. This study confirms the occurrence of oxidative stress in IUGR and demonstrates the beneficial effect of arginine/acetylsalicylic acid therapy in reducing oxidative stress in IUGR.