Placental nutrient transfer capacity and fetal growth

Myc promotes polyploidy in murine trophoblast cells and suppresses senescence

The placenta is essential for reproductive success. The murine placenta includes polyploid giant cells that are crucial for its function. Polyploidy occurs broadly in nature but its regulators and significance in the placenta are unknown. We have discovered that many murine placental cell types are polyploid and have identified factors that license polyploidy using single-cell RNA sequencing. Myc is a key regulator of polyploidy and placental development, and is required for multiple rounds of DNA replication, likely via endocycles, in trophoblast giant cells. Furthermore, MYC supports the expression of DNA replication and nucleotide biosynthesis genes along with ribosomal RNA. Increased DNA damage and senescence occur in trophoblast giant cells without Myc, accompanied by senescence in the neighboring maternal decidua. These data reveal Myc is essential for polyploidy to support normal placental development, thereby preventing premature senescence. Our study, combined with available literature, suggests that Myc is an evolutionarily conserved regulator of polyploidy.

Role of melatonin receptor 1B gene polymorphism and its effect on the regulation of glucose transport in gestational diabetes mellitus

Melatonin receptor 1B (MT2, encoded by the MTNR1B gene), a high-affinity receptor for melatonin, is associated with glucose homeostasis including glucose uptake and transport. The rs10830963 variant in the MTNR1B gene is linked to glucose metabolism disorders including gestational diabetes mellitus (GDM); however, the relationship between MT2-mediated melatonin signaling and a high birth weight of GDM infants from maternal glucose abnormality remains poorly understood. This article aims to investigate the relationship between rs10830963 variants and GDM development, as well as the effects of MT2 receptor on glucose uptake and transport in trophoblasts. TaqMan-MGB (minor groove binder) probe quantitative real-time polymerase chain reaction (qPCR) assays were used for rs10930963 genotyping. MT2 expression in the placenta of GDM and normal pregnant women was detected by immunofluorescence, western blot, and qPCR. The relationship between MT2 and glucose transporters (GLUTs) or peroxisome proliferator-activated receptor γ (PPARγ) was established by western blot, and glucose consumption of trophoblasts was measured by a glucose assay kit. The results showed that the genotype and allele frequencies of rs10830963 were significantly different between GDM and normal pregnant women (P<0.05). The fasting, 1-h and 2-h plasma glucose levels of G-allele carriers were significantly higher than those of C-allele carriers (P<0.05). Besides, the protein and messenger RNA (mRNA) expression of MT2 in the placenta of GDM was significantly higher than that of normal pregnant women (P<0.05). Melatonin could stimulate glucose uptake and GLUT4 and PPARγ protein expression in trophoblasts, which could be attenuated by MT2 receptor knockdown. In conclusion, the rs10830963 variant was associated with an increased risk of GDM. The MT2 receptor is essential for melatonin to raise glucose uptake and transport, which may be mediated by PPARγ.

Placental Super Micro-vessels Segmentation Based on ResNeXt with Convolutional Block Attention and U-Net

Accurate placenta super micro-vessels segmentation is the key to diagnose placental diseases. However, the current automatic segmentation algorithm has issues of information redundancy and low information utilization, which reduces the segmentation accuracy. To solve this problem, we propose a model based on ResNeXt with convolutional block attention module (CBAM) and UNet (RC-UNet) for placental super micro-vessels segmentation. In the RC-UNet model, we choose the UNet as the backbone network for initial feature extraction. At the same time, we select ResNeXt-CBAM as the attention module for feature refinement and weighting. Specifically, we stack the blocks of the same topology following the split-transform-merge strategy to reduce the redundancy of hyperparameter. Moreover, we conduct CBAM processing on each group of the detailed features to get informative features and suppress unnecessary features, which improve the information utilization. The experiments on the self-collected data show that the proposed algorithm has better segmentation results for anatomical structures (umbilical cord blood (UC), stem villus (ST), maternal blood (MA)) than other selected algorithms.

Gestational age and maternal status of DHA and other polyunsaturated fatty acids in pregnancy: A systematic review

INTRODUCTION

Maternal diet is important in determining omega-3 DHA status however there is limited knowledge of other factors influencing maternal omega-3 concentrations during pregnancy. The primary objective of this systematic review and meta-analysis was to evaluate whether maternal DHA status changed across gestation. Changes in levels of other key polyunsaturated fatty acids were also investigated.

MATERIALS AND METHODS

The Medline, Embase, Amed, and CINAHL databases were searched. Included studies reported measures of maternal omega-3 status in at least two pregnancy trimesters.

RESULTS

Thirteen studies were included in the final analyses. Absolute omega-3 DHA concentrations increased across gestation, but decreased as a proportion of total lipids.

DISCUSSION

Our findings are consistent with previous observations of increases in lipid mobilisation, coupled with preferential transfer of DHA to the fetus, with advancing gestation. However the number of eligible studies was small and further investigations are required.

Developmental Programming of Obesity and Diabetes in Mouse, Monkey, and Man in 2018: Where Are We Headed?

Childhood obesity and its comorbidities continue to accelerate across the globe. Two-thirds of pregnant women are obese/overweight, as are 20% of preschoolers. Gestational diabetes mellitus (GDM) is escalating, affecting up to 1 in 5 pregnant women. The field of developmental origins of health and disease has begun to move beyond associations to potential causal mechanisms for developmental programming. Evidence across species compellingly demonstrates that maternal obesity, diabetes, and Western-style diets create a long-lasting signature on multiple systems, including infant stem cells, the early immune system, and gut microbiota. Such exposures accelerate adipogenesis, disrupt mitochondrial metabolism, and impair energy sensing, affecting neurodevelopment, liver, pancreas, and skeletal muscle. Attempts to prevent developmental programming have met with very limited success. A challenging level of complexity is involved in how the host genome, metabolome, and microbiome throughout pregnancy and lactation increase the offspring's risk of metabolic diseases across the life span. Considerable gaps in knowledge include the timing of exposure(s) and permanence or plasticity of the response, encompassing effects from both maternal and paternal dysmetabolism. Basic, translational, and human intervention studies targeting pathways that connect diet, microbiota, and metabolism in mothers with obesity/GDM and their infants are a critical unmet need and present new challenges for disease prevention in the next generation.

Switching obese mothers to a healthy diet improves fetal hypoxemia, hepatic metabolites, and lipotoxicity in non-human primates

Objective

Non-alcoholic fatty liver disease (NAFLD) risk begins in utero in offspring of obese mothers. A critical unmet need in this field is to understand the pathways and biomarkers underlying fetal hepatic lipotoxicity and whether maternal dietary intervention during pregnancy is an effective countermeasure.

Methods

We utilized a well-established non-human primate model of chronic, maternal, Western-style diet induced obesity (OB-WSD) compared with mothers on a healthy control diet (CON) or a subset of OB-WSD mothers switched to the CON diet (diet reversal; OB-DR) prior to and for the duration of the next pregnancy. Fetuses were studied in the early 3rd trimester.

Results

Fetuses from OB-WSD mothers had higher circulating triglycerides (TGs) and lower arterial oxygenation suggesting hypoxemia, compared with fetuses from CON and OB-DR mothers. Hepatic TG content, oxidative stress (TBARs), and de novo lipogenic genes were increased in fetuses from OB-WSD compared with CON mothers. Fetuses from OB-DR mothers had lower lipogenic gene expression and TBARs yet persistently higher TGs. Metabolomic profiling of fetal liver and serum (umbilical artery) revealed distinct separation of CON and OB-WSD groups, and an intermediate phenotype in fetuses from OB-DR mothers. Pathway analysis identified decreased tricarboxylic acid cycle intermediates, increased amino acid (AA) metabolism and byproducts, and increased gluconeogenesis, suggesting an increased reliance on AA metabolism to meet energy needs in the liver of fetuses from OB-WSD mothers. Components in collagen synthesis, including serum protein 5-hydroxylysine and hepatic lysine and proline, were positively correlated with hepatic TGs and TBARs, suggesting early signs of fibrosis in livers from the OB-WSD group. Importantly, hepatic gluconeogenic and arginine related intermediates and serum levels of lactate, pyruvate, several AAs, and nucleotide intermediates were normalized in the OB-DR group. However, hepatic levels of CDP-choline and total ceramide levels remained high in fetuses from OB-DR mothers.

Conclusions

Our data provide new metabolic evidence that, in addition to fetal hepatic steatosis, maternal WSD creates fetal hypoxemia and increases utilization of AAs for energy production and early activation of gluconeogenic pathways in the fetal liver. When combined with hyperlipidemia and limited antioxidant activity, the fetus suffers from hepatic oxidative stress and altered intracellular metabolism which can be improved with maternal diet intervention. Our data reinforce the concept that multiple “first hits” occur in the fetus prior to development of obesity and demonstrate new biomarkers with potential clinical implications for monitoring NAFLD risk in offspring.

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Maternal WSD increases fetal hypoxemia and utilization of AAs for gluconeogenesis.

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Maternal WSD increases fetal oxidative stress and precursors to liver fibrosis.

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Carnosine and l-proline uniquely correlated with fetal TG and oxidative stress.

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Fetal TGs were correlated with fetal arterial oxygen saturation.

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Diet reversal in obese WSD mothers prevents fetal hypoxemia and oxidative stress.

Postnatal RBC arachidonic and docosahexaenoic acids deficiencies are associated with higher risk of neonatal morbidities and mortality in preterm infants

Arachidonic (AA) and docosahexaenoic (DHA) acids are essential for the health and development of the neonate. Red blood cell (RBC) fatty acids were analyzed in 583 very low birth weight (VLBW) infants and 274 term infants using capillary gas chromatography. VLBW infants exhibited significantly lower RBC AA (13.0 ± 0.89 vs. 13.5 ± 0.98) and DHA (3.77 ± 0.60 vs. 3.80 ± 0.62), but higher n6:n3 ratio (3.97 ± 0.46 vs. 3.63 ± 0.37) than term infants. In VLBW infants, DHA was lower in those born with small for gestational age (3.69 ± 0.57 vs. 3.86 ± 0.58) and those who suffered from neonatal sepsis (3.73 ± 0.60 vs. 3.86 ± 0.55). Both AA and DHA were significantly lower in infants who developed respiratory distress syndrome or intraventricular hemorrhage, and those who died during the hospital stay. VLBW infants had lower postnatal RBC AA and DHA levels than term infants did. These deficits are associated with higher risk of neonatal morbidities and mortality.

Proximity to Delivery Alters Insulin Sensitivity and Glucose Metabolism in Pregnant Mice

In late pregnancy, maternal insulin resistance occurs to support fetal growth, but little is known about insulin-glucose dynamics close to delivery. This study measured insulin sensitivity in mice in late pregnancy at day 16 (D16) and near term at D19. Nonpregnant (NP) and pregnant mice were assessed for metabolite and hormone concentrations, body composition by DEXA, tissue insulin signaling protein abundance by Western blotting, glucose tolerance and utilization, and insulin sensitivity using acute insulin administration and hyperinsulinemic-euglycemic clamps with [(3)H]glucose infusion. Whole-body insulin resistance occurred in D16 pregnant dams in association with basal hyperinsulinemia, insulin-resistant endogenous glucose production, and downregulation of several proteins in hepatic and skeletal muscle insulin signaling pathways relative to NP and D19 values. Insulin resistance was less pronounced at D19, with restoration of NP insulin concentrations, improved hepatic insulin sensitivity, and increased abundance of hepatic insulin signaling proteins. At D16, insulin resistance at whole-body, tissue, and molecular levels will favor fetal glucose acquisition, while improved D19 hepatic insulin sensitivity will conserve glucose for maternal use in anticipation of lactation. Tissue sensitivity to insulin, therefore, alters differentially with proximity to delivery in pregnant mice, with implications for human and other species.

Fate of orally administered radioactive fatty acids in the late-pregnant rat

To investigate the biodisponibility of placental transfer of fatty acids, rats pregnant for 20 days were given tracer amounts of [(14)C]palmitic (PA), oleic (OA), linoleic (LA), α-linolenic (LNA), or docosahexaenoic acid (DHA) orally and euthanized at 0.5, 1.0, 2.0, or 8.0 h thereafter. Maternal plasma radioactivity in lipids initially increased only to decline at later times. Most of the label appeared first as triacylglycerols (TAG); later, the proportion in phospholipids (PhL) increased. The percentage of label in placental lipids was also always highest shortly after administration and declined later; again, PhL increased with time. Fetal plasma radioactivity increased with time, with its highest value at 8.0 h after DHA or LNA administration. DHA initially appeared primarily in the nonesterified fatty acids (NEFA) and PA, OA, LA, and LNA as TAG followed by NEFA; in all cases, there was an increase in PhL at later times. Measurement of fatty acid concentrations allowed calculation of specific (radio)activities, and the ratio (fetal/maternal) of these in the plasmas gave an index of placental transfer activity, which was LNA > LA > DHA = OA > PA. It is proposed that a considerable proportion of most fatty acids transferred through the placenta are released into the fetal circulation in the form of TAG.

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

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

Role of mouse Wdr13 in placental growth; a genetic evidence for lifetime body weight determination by placenta during development

Placental development is essential for implantation and growth of foetus in the uterus of eutherian mammals. Numerous growth factors are responsible for placental development and cell lineage differentiation. Gene knockout mice have shown role of various genes in the placenta. Here using Wdr13 knockout mice, we show that this gene is important for proper placental development. Wdr13, a X-linked gene, expresses in multiple trophoblast cell types of placenta and the mutant placenta had reduced size after 17.5 dpc due to reduction of junctional zone (JZ) and labyrinth zone (LZ). We observed reduction in levels of angiopoietin-2 and cd44 mRNA in Wdr13 mutant placenta as compared to that in the wild type. Our findings show that Wdr13 is required for normal placental development and cell differentiation. Wdr13 heterozygous female placenta when the mutant allele was of maternal origin showed similar defects as those in case of Wdr13 null placenta. Using two types of heterozygous females carrying either maternally and paternally derived mutant Wdr13 allele we provide genetic evidence that development of placenta determines body weight of mice for the entire life.

Comparative proteomics analysis suggests that placental mitochondria are involved in the development of pre-eclampsia

INTRODUCTION

Pre-eclampsia (PE), a severe pregnancy-specific disease characterized by the new onset of hypertension, proteinuria, edema, and a series of other systematic disorders, is a state of widespread mitochondrial dysfunction of the placenta.

METHODS

We compared the morphology of mitochondria in pre-eclamptic and normotensive placentae using electron microscopy. To reveal the systematic protein expression changes of placental mitochondria that might explain the pathogenesis of PE, we performed iTRAQ analysis combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) on differentially expressed placental mitochondria proteins from 4 normotensive and 4 pre-eclamptic pregnancies. Bioinformatics analysis was used to find the relative processes that these differentially expressed proteins were involved in. Three differentially expressed proteins were chosen to confirm by Western blotting and immunohistochemistry.

RESULTS

Morphological data demonstrated degenerative and apoptotic changes in the mitochondria of pre-eclamptic placentae. We found four proteins were upregulated and 22 proteins were downregulated in pre-eclamptic placentae compared with normotensive placentae. Bioinformatics analysis showed that these proteins were involved in many critical processes in the development of pre-eclampsia such as apoptosis, fatty acid oxidation, the respiratory chain, reactive oxygen species generation, the tricarboxylic acid cycle and oxidative stress.

CONCLUSIONS

This preliminary work provides a better understanding of the proteomic alterations of mitochondria from pre-eclamptic placentae and may aid in our understanding of the importance of mitochondria in the development of pre-eclampsia.

Decreased mitochondrial fatty acid oxidation in placentas from women with preeclampsia

Preeclampsia is a leading cause of maternal and fetal morbidity and mortality in high and low-income countries. The aetiology of preeclampsia is multifactorial and remains obscure. Some evidences suggest that altered placental fatty acid oxidation might play a role in the pathogenesis of preeclampsia. To reveal if placental fatty acid oxidation is reduced in preeclampsia, we evaluate the expression levels of enzymes of mitochondrial fatty acid oxidation using quantitative Real-time PCR and the fatty acid oxidation rate in placental explants. We found that long-chain 3-hydroxyacyl-CoA dehydrogenase levels and fatty acid oxidation capacity were significantly reduced in placentas from women with preeclampsia.

Maternal and fetal exposure to pesticides associated to genetically modified foods in Eastern Townships of Quebec, Canada

Pesticides associated to genetically modified foods (PAGMF), are engineered to tolerate herbicides such as glyphosate (GLYP) and gluphosinate (GLUF) or insecticides such as the bacterial toxin bacillus thuringiensis (Bt). The aim of this study was to evaluate the correlation between maternal and fetal exposure, and to determine exposure levels of GLYP and its metabolite aminomethyl phosphoric acid (AMPA), GLUF and its metabolite 3-methylphosphinicopropionic acid (3-MPPA) and Cry1Ab protein (a Bt toxin) in Eastern Townships of Quebec, Canada. Blood of thirty pregnant women (PW) and thirty-nine nonpregnant women (NPW) were studied. Serum GLYP and GLUF were detected in NPW and not detected in PW. Serum 3-MPPA and CryAb1 toxin were detected in PW, their fetuses and NPW. This is the first study to reveal the presence of circulating PAGMF in women with and without pregnancy, paving the way for a new field in reproductive toxicology including nutrition and utero-placental toxicities.

Umbilical venous–arterial plasma composition differences suggest differential incorporation of fatty acids in NEFA and cholesteryl ester pools

The developing fetus requires an adequate supply of fatty acids, in particular PUFA, for optimal growth and development. Little is known about the transfer of fatty acids by the placenta into the fetal circulation. However, the molecular form in which fatty acids are transferred into the fetal circulation may influence their metabolism and hence their availability to specific tissues. The aim of the present study was to determine which lipid pools in the fetal circulation become enriched in fatty acids from the placenta by comparing the fatty acid compositions of individual lipid pools between umbilical venous (UV) and umbilical arterial (UA) plasma. Plasma from the UV and UA was collected after delivery from ten uncomplicated pregnancies, and the fatty acid composition of each lipid class was determined by GC. Total NEFA concentration in the UV was twofold higher than in the UA (P < 0·05) due to enrichment in 16 : 0, 16 : 1n-7, 18 : 1n-9, 18 : 1n-7, 18 : 2n-6, 20 : 3n-6, 20 : 4n-6, 24 : 0 and 22 : 6n-3. Total cholesteryl ester concentration was twofold higher in the UV than in the UA (P < 0·05) due to enrichment in 16 : 0, 16 : 1n-7, 18 : 0, 18 : 1n-9, 18 : 1n-7, 18 : 2n-6 and 20 : 4n-6. There were no significant UV–UA differences in the total concentration or composition of TAG or phosphatidylcholine. The present study demonstrates differential enrichment across the placenta of fatty acids into specific lipid pools in the fetal circulation. Such partitioning may facilitate supply of individual fatty acids to specific fetal tissues.

Early life nutrition and metabolic programming

Research investigating the early programming of adult metabolic disease has in recent years provided much mechanistic insight into how the early environment impacts on long-term health. It includes studies addressing the roles of intrauterine nutrient availability, which is determined by maternal nutrition, maternal exposure to oxygen, toxic events, and infection; the placental interface; and also the early postnatal environment. This review will explore the epidemiological evidence for programming of metabolic disease and provide an overview of the various studies using animals to model metabolic phenotypic outcome. It will also discuss evidence for the proposed molecular mechanisms and the potential for intervention.

[Effects of omega 3 supplementation in pregnant women]

Maternal nutrition is a major environmental factor, which can be modified and can affect fetal growth and development with potential long-term consequences. There is currently a strong mediatic pressure for supplementing diets with omega 3 fatty acids. Nevertheless, if beneficial effects seem to be confirmed in adults and in animal models, the evidence for favourable effects of omega 3 supplementation in pregnant women are less obvious. Indeed, there is a trend showing a positive effect on cerebral development, but long term effects have not been demonstrated and both the quantity of omega 3 and the omega 3:omega 6 ratios are not precisely determined. Numerous studies are needed, both in pregnant animal models and in patients, to unravel these effects.

Prenatal exposure to pesticides: analysis of human placental acetylcholinesterase, glutathione S-transferase and catalase as biomarkers of effect

Pre- and perinatal exposure to pesticides is deleterious on foetal and neonatal development, but information regarding possible effects on environmental low-dose exposure to pesticides is scarce. Most epidemiological studies of the health effect of pesticides have been based on self-reported information. However, detailed information on past pesticide use is difficult to reconstruct. This is a current study conducted among pregnant mothers attending a delivery care and perinatal programme at a public hospital. The study investigates biomarkers of early effects in placentas from women living in an area with an intensive use of pesticides in the northern part of Patagonia, province of Río Negro, Argentina, and it assesses the consistency of the information provided by self-reports. The study confirms that placental acetylcholinesterase and catalase activities are significantly associated with periods of organophosphorus pesticides application, while glutathione S-transferase is not affected. We found a positive correlation between environmental exposure to organophosphorus pesticides and carbamate insecticides and newborn head circumference. The findings provide a further indication of a link between placenta acetylcholinesterase and catalase activity and prenatal exposure to pesticides in population studies. Both placenta enzymes may be used as biomarkers in health surveillance programmes for early diagnosis of exposure related alterations produced by organophosphorus pesticides and carbamate pesticides.

Mechanisms by which poor early growth programs type-2 diabetes, obesity and the metabolic syndrome

Fetal programming is gaining momentum as a highly documented phenomenon which links poor early growth to adult disease. It is backed up by large cohorts in epidemiological studies worldwide and has been tested in various animal models. The root causes of programming link closely with maternal condition during pregnancy, and therefore the fetal environment. Suboptimal fetal environments due to poor or inadequate nutrition, infection, anemia, hypertension, inflammation, gestational diabetes or hypoxia in the mother expose the fetus to hormonal, growth factor, cytokine or adipokine cues. These in turn act to alter metabolic, immune system, vascular, hemodynamics, renal, growth and mitochondrial parameters respectively and most evidently in the later stages of life where they impact on the individual as poor glucose homeostasis, insulin resistance, type 2 diabetes, hypertension, cardiovascular disease, obesity and heart disease. These events are compounded by over-nutrition or lifestyle choices which are in conflict with the programming of the fetus. We and others have utilised various species to test the early life programming hypothesis and to identify key molecular mechanisms. With parallel studies of human cohorts, these molecular markers can be validated as realistic targets for intervention.

Effect of nutrient intake during pregnancy on fetal and placental growth and vascular development

Remarkable diversity of size and health of offspring exists after normal pregnancies. When pregnancies are complicated by an extrinsic variable such as inappropriate maternal nutrition, birth weight and health of the neonate are substantially affected. The placenta is the organ through which respiratory gases, nutrients, and wastes are exchanged between the maternal and fetal systems. Thus, transplacental exchange provides for all the metabolic demands of fetal growth. Transplacental exchange is dependent upon uterine and umbilical blood flow, and blood flow rates are in turn dependent in large part upon vascularization of the placenta. Therefore, factors that influence placental vascular development will have a dramatic impact on fetal growth and development, and thereby on neonatal mortality and morbidity. Recent work from our laboratories has focused on the effects of nutrient intake during pregnancy on placental growth and vascular development. Both nutrient restriction of the adult dam and overnourishment of the adolescent dam during pregnancy suppress placental cell proliferation and vascularity. Furthermore, placental expression of angiogenic factors and their receptors, factors that are known to affect vascular growth, are perturbed by level of nutrition. Studies in this area will lead to improved methods to manage nutritionally-compromised pregnancies.

In vivo hyperglycemia and its effect on Glut-1 expression in the embryonic heart

BACKGROUND

Maternal diabetes exposes embryos to periods of hyperglycemia. Glucose is important for normal cardiogenesis, and Glut-1 is the predominant glucose transporter in the embryo.

METHODS

Pregnant mice were exposed to 6 or 12 hr hyperglycemia during organogenesis using intraperitoneal (IP) injections of D-glucose on gestational day (GD) 9.5 (plug = GD 0.5). Embryos were examined for morphology and total cardiac protein, and embryonic hearts were evaluated for Glut-1 protein and mRNA expression immediately after treatment (GD 9.75, GD 10.0), as well as on GD 10.5 and GD 12.5.

RESULTS

IP glucose injections were effective in producing sustained maternal hyperglycemia. Maternal hyperglycemia for 6 or 12 hr on GD 9.5, followed by normoglycemia, produced a decrease in overall size and total cardiac protein in embryos evaluated on GD 10.5 but no difference on GD 12.5. Cardiac Glut-1 expression was immediately upregulated in embryos exposed to 6 or 12 hr maternal hyperglycemia. On GD 10.5, cardiac Glut-1 expression was not different in embryos exposed to maternal hyperglycemia for 6 hr but was downregulated in embryos exposed for 12 hr. On GD 12.5, cardiac Glut-1 expression in embryos exposed to maternal hyperglycemia on GD 9.5 for 6 or 12 hr, followed by normoglycemia, was not different from controls. The temporal pattern was the same for Glut-1 protein and mRNA expression.

CONCLUSIONS

Hyperglycemia-induced alterations in Glut-1 expression likely interfere with balance of glucose available to the embryonic heart that may affect cardiac morphogenesis.

Regulation of insulin-like growth factor-I and insulin-like growth factor binding protein-1 concentrations in preterm fetuses

OBJECTIVE

Our purpose was to evaluate which factors regulate insulin-like growth factor-I and insulin-like growth factor binding protein-1 concentrations in preterm fetuses.

STUDY DESIGN

We studied 76 singleton births between 25 and 36 weeks of gestation. Forty-nine pregnancies were complicated by hypertensive disease; 24 pregnancies were complicated by preterm labor or preterm rupture of membranes; and antenatal glucocorticoids were given in 49 pregnancies. Pathology reports showed infarct(s) or hematoma(s) in 31 of 69 placentas. We recorded blood gas values in umbilical artery and vein and measured glucose, C-peptide, and insulin-like growth factor-I and insulin-like growth factor binding protein-1 concentrations in umbilical vein.

RESULTS

Birth weight correlated with umbilical vein insulin-like growth factor-I (r = 0.68, P <.0001) and inversely with insulin-like growth factor binding protein-1 (r = -0.26, P =.02). Babies with birth weight of </=25th percentile had lower insulin-like growth factor-I but higher insulin-like growth factor binding protein-1 levels than babies at >25th percentile. Two-factor analysis of variance showed that umbilical vein insulin-like growth factor-I was determined by gestational age (P =.0004) and birth weight percentile (P <.0001), whereas insulin-like growth factor binding protein-1 was not affected by gestational age. Umbilical vein C-peptide was highly correlated with insulin-like growth factor binding protein-1 (r = -0.55, P <.0001), but not insulin-like growth factor-I, levels. Blood gas values in umbilical artery and vein, particularly umbilical artery PO (2), were correlated with umbilical vein insulin-like growth factor-I and insulin-like growth factor binding protein-1 (r = 0.51 and -0.48, respectively; P <.0001); changes in insulin-like growth factor-I and insulin-like growth factor binding protein-1 occurred at umbilical artery PO (2) <14.8 mm Hg. Multiple regression analysis showed that umbilical vein insulin-like growth factor-I was predicted by umbilical artery PO (2), gestational age, and the presence of placental infarcts/hematomas (R (2) of model = 0.58, P <.0001), and umbilical vein insulin-like growth factor binding protein-1 by umbilical vein C-peptide, umbilical artery PO (2), and placental infarcts/hematomas (R (2) = 0.49, P <.0001).

CONCLUSION

In the preterm fetus, circulating insulin-like growth factor-I is related to gestational age and the in utero growth potential, whereas insulin-like growth factor binding protein-1 is related only to the in utero growth potential. The PO (2) is a robust determinant of both insulin-like growth factor-I and insulin-like growth factor binding protein-1 levels; hypoxia may restrain fetal growth through its effects on the insulin-like growth factor/insulin-like growth factor binding protein axis. Insulin is a powerful determinant of insulin-like growth factor binding protein-1, but not insulin-like growth factor-I, concentrations in the preterm fetus.

Placental regulation of fatty acid delivery and its effect on fetal growth--a review

More than 90 per cent of the fat deposition in the fetus occurs in the last 10 weeks of pregnancy during which it increases exponentially to reach a rate of accretion of around 7 g/day close to term. All of the n -3 and n -6 fatty acid structure acquired by the fetus has to cross the placenta and fetal blood is enriched in long chain polyunsaturated fatty acids (LCPUFA) relative to the maternal supply. The placenta may regulate its own fatty acid substrate supply via the action of placental leptin on maternal adipose tissue. Fatty acids cross the microvillous and basal membranes by simple diffusion and via the action of membrane bound and cytosolic fatty acid binding proteins (FABPs). The direction and magnitude of fatty acid flux is mainly dictated by the relative abundance of available binding sites. The fatty acid mix delivered to the fetus is largely determined by the fatty acid composition of the maternal blood although the placenta is able to preferentially transfer the important PUFA to the fetus as a result of selective uptake by the syncytiotrophoblast, intracellular metabolic channelling of individual fatty acids, and selective export to the fetal circulation. Placental FABP polymorphisms may affect these processes. There is little evidence to suggest that placental delivery of fatty acids limits normal fetal growth although the importance of the in utero supply may be to support post-natal development as most of the LCPUFA accumulated by the fetus is stored in the adipose tissue for use in early post-natal life.