Fetal Plasma Concentrations Research Articles

Effects of Dose, Administration Route, and/or Vehicle on Decabromodiphenyl Ether Concentrations in Plasma of Maternal, Fetal, and Neonatal Rats and in Milk of Maternal Rats

The effects of route and vehicle on blood and milk levels of decabromodiphenyl ether (DecaBDE; CASRN 1163-19-5) were investigated in the rat to assist in the design and conduct of a developmental neurotoxicity study. Blood plasma and/or milk concentrations were determined in dams, fetuses, and/or nursing pups after repeated DecaBDE administration by gavage throughout gestation or gestation and lactation using corn oil (CO) or soyaphospholipon/Lutrol F 127-water (SPL) as the vehicle. The impact of vehicle on plasma levels was also investigated in pups derived from naive dams after a single postnatal dose. This study reports for the first time fetal and neonatal plasma concentrations concurrent with those of maternal plasma and/or milk. Higher concentrations of DecaBDE were achieved in plasma and in milk with CO than with SPL. Furthermore, pups derived from dams treated with only SPL were lower in body weight, compared with those from dams treated with either CO, CO and DecaBDE, or SPL and DecaBDE. The study further shows that exposure to DecaBDE is relatively consistent across the dose range of 100 to 1000 mg/(kg · day) when administered in CO.

Influence of verapamil on pharmacokinetics and transplacental transfer of ivermectin in sheep

In pregnant sheep at 120–128 days of gestational age, a study was done to evaluate the effect of the co-administration of verapamil (Vpm) and ivermectin (IVM) on the maternal and fetal disposition kinetics after intravenous administration of IVM. Ten pregnant Suffolk Down sheep of 63.5 ± 6.6 kg body weight (bw) were surgically prepared to insert polyvinyl catheters in the fetal femoral artery and vein and amniotic sac. The ewes were randomly assigned to two experimental groups. In Group 1 (control), 5 ewes were treated with an intravenous bolus of 0.2 mg IVM/kg bw. In Group 2 (Vpm-IVM), 5 ewes were subcutaneously treated with Vpm (2.5 mg/kg × 3 doses at 12 h intervals) and 0.2 mg/kg IVM by intravenous route. Maternal and fetal blood samples were taken before and after IVM administration during a 144 h post-treatment period. Samples were analyzed by liquid chromatography (HPLC). A non-compartmental pharmacokinetic analysis was performed and statistical differences were determined using the Mann–Whitney U-test. Significantly higher IVM levels in maternal plasma concentrations were determined after co-administration of Vpm/IVM compared with the group treated with IVM alone. Significant decreases in the volume of distribution and in the half-life of elimination ( t ½ β ) were observed in the Vpm/IVM treated group. A significantly faster ( T max) and higher ( C max) ( P < 0.05) increase in IVM fetal plasma concentrations were observed in the group of fetuses from pregnant ewes treated with Vpm/IVM. The results of our study support the hypothesis that pharmacological blockage of P-glycoprotein with Vpm can increase the transfer of IVM to fetal circulation.

The relation of S100beta and metabolic and endocrine responses to acute fetal hypoxemia

Elevations in S100beta protein in umbilical cord blood have been proposed as a reproducible marker of fetal stress, leading to cell damage within the central nervous system. However, it remains unknown whether fetal S100beta concentrations correlate with established endocrine and metabolic indices of fetal distress. Hence, in the late gestation ovine fetus, plasma concentrations of S100beta, adrenocorticotropic hormone (ACTH), cortisol, neuropeptide Y (NPY), and catecholamines and blood concentrations of glucose and lactate were measured during acute hypoxemia. Under general anesthesia, 5 sheep fetuses were chronically instrumented with catheters and subjected 5 days later to 1h normoxia, 0.5h hypoxemia and 1h recovery. Plasma samples were taken during each experimental period. Hypoxemia induced significant falls in PaO2 with increases in fetal plasma concentrations of ACTH, cortisol, catecholamines and NPY, and elevations in blood glucose and lactate, all of which showed significant positive relationships with fetal plasma S100beta concentrations. Hence, evaluation of S100beta may provide a valuable clinical tool in the assessment of fetal well-being in suspected complicated pregnancies.

Up-regulation of Toll-like receptor 4/nuclear factor-kappaB signaling is associated with enhanced adipogenesis and insulin resistance in fetal skeletal muscle of obese sheep at late gestation.

Maternal obesity is increasing at an alarming rate. We previously showed that maternal obesity induces an inflammatory response and enhances adipogenesis in fetal skeletal muscle at midgestation. The objective of this study was to evaluate effects of maternal obesity on adipogenesis, inflammatory signaling, and insulin pathways at late gestation when ovine fetal skeletal muscle matures. Nonpregnant ewes were assigned to a control diet (Con, fed 100% of National Research Council nutrient recommendations, n = 6) or obesogenic diet (OB, fed 150% of National Research Council recommendations, n = 6) from 60 d before to 135 d after conception (term 148 d) when the fetal semitendenosus skeletal muscle was sampled. Expression of the adipogenic marker, peroxisome proliferator-activated receptor-gamma, was increased in OB compared with Con fetal semitendenosus muscle, indicating up-regulation of adipogenesis. More intramuscular adipocytes were observed in OB muscle. Phosphorylation of inhibitor-kappaB kinase-alpha/beta and nuclear factor-kappaB RelA/p65 were both increased in OB fetal muscle, indicating activation of nuclear factor-kappaB pathway. Phosphorylation of c-Jun N-terminal kinase and c-Jun (at Ser 63 and Ser 73) was also elevated. Toll-like receptor 4 expression was higher in OB than Con fetal muscle. Moreover, despite higher insulin concentrations in OB vs. Con fetal plasma (2.89 +/- 0.53 vs. 1.06 +/- 0.52 ng/ml; P < 0.05), phosphorylation of protein kinase B at Ser 473 was reduced, indicating insulin resistance. In conclusion, our data show maternal obesity-induced inflammatory signaling in late gestation fetal muscle, which correlates with increased im adipogenesis and insulin resistance, which may predispose offspring to later-life obesity and diabetes.

Fetal lipid metabolism is regulated by the Liver X Receptor (LXR) in mice

The Liver X Receptors LXRa/ß are vitally important in regulating cholesterol and fatty acid metabolism in the adult. Aim of this study was to elucidate the role of LXR in the fetal mouse liver. Pregnant C57BL/6 mice or Lxra+/− mice crossed heterozygously were fed a diet containing the synthetic LXR agonist T0901317 from E10.5 until delivery. In fetuses and dams, gene expression and lipid levels were monitored. In the mouse fetus, hepatic expression of LXR target genes (e.g., Srebp1c, Fas and Abcg5) is low during gestation and increases after birth. Lxra itself is expressed at ~40 % of adult levels, whereas the expression of Lxrb is 2.5‐3 times higher than in adult control liver. Upon administration of T0901317, LXR target genes are activated in the fetal liver: expression of the cholesterol transporter Abcg5 is 45 times induced. Expression of Srebp1c and Fas is increased 2.0‐ to 5.3‐fold and 1.7‐ to 2.0‐fold, respectively. Consequently, triglyceride concentrations in fetal liver and plasma are raised up to 2.7‐ and 1.5‐fold. Cholesterol levels in plasma are doubled upon treatment, whereas hepatic cholesterol concentrations are unchanged. In Lxra−/− fetuses, these changes are reduced but not absent.ConclusionLxra and Lxrß are functionally active in fetal mouse liver when stimulated with the synthetic agonist T0901317. Similar to adult mice, cholesterol homeostasis and de novo lipogenesis can be influenced experimentally by administration of this agonist.Supported by the Dutch Heart Foundation (2004T048).

Blockade of PGHS-2 inhibits the hypothalamus-pituitary-adrenal axis response to cerebral hypoperfusion in the sheep fetus

Decreases in fetal blood pressure stimulate homeostatic stress responses that help return blood pressure to normal levels. Fetal hypothalamus-pituitary-adrenal (HPA) axis responses to hypotension are mediated by chemoreceptor and baroreceptor reflexes and ischemia of the fetal central nervous system. Indomethacin, a nonselective inhibitor of prostaglandin endoperoxide synthase (PGHS)-1 and -2, attenuates the HPA response to hypotension in the fetus. The present study was designed to test the hypothesis that selective inhibition of PGHS-2 also inhibits the HPA response to cerebral hypoperfusion. We studied 13 chronically catheterized fetal sheep (126-136 days gestation). Five fetal sheep were subjected to intracerebroventricular infusion of nimesulide (0.01 mg/day), a specific inhibitor of PGHS-2, and eight were treated with vehicle (DMSO in water) for 5 days. Each fetus was subjected to a 10-min period of brachiocephalic occlusion, which decreased carotid arterial pressure approximately 75% and reflexively increased fetal plasma concentrations of ACTH, POMC, cortisol, and femoral arterial pressure, and decreased fetal heart rate. Nimesulide significantly inhibited the ACTH response to the BCO, while significantly augmenting the reflex cardiovascular response and altering fetal heart rate variability consistent with increased sympathetic nervous system activity. The results of this study demonstrate that the activity of PGHS-2 in the brain is a necessary component of the fetal HPA response to cerebral hypoperfusion in the late-gestation fetal sheep. These results are consistent with those of recent study, in which we demonstrated that the preparturient increase in fetal ACTH secretion depends upon PGHS-2 activity within the fetal brain.

Down-Regulation of Growth Signaling Pathways Linked to a Reduced Cotyledonary Vascularity in Placentomes of Over-Nourished, Obese Pregnant Ewes

Both protein kinase B (Akt) and extracellular signal-regulated kinase 1/2 (ERK1/2) are down-stream components of the insulin/insulin like growth factor-1 (IGF-1) signaling pathway. AMP-activated protein kinase (AMPK) is known to sensitize cells to insulin/IGF-1 signaling. The objective of this study was to assess the activity of AMPK and its role in the observed down-regulation of insulin/IGF-1 signaling in cotyledonary (COT) arteries supplying the placental component of the ewe placentome. Nonpregnant ewes were randomly assigned to a control (C, 100% of NRC recommendations) or obesogenic (OB, 150% of NRC) diet from 60 days before conception until necropsy on day 75 of gestation ( n = 5/group) or until lambing ( n = 5/group). At necropsy on day 75 of gestation, the smallest terminal arteries that entered the COT tissues (0.5–1.0 mm in diameter) were collected for analyses. Fetal weights were ∼20% greater ( P < 0.05) on OB than C ewes, but birth weights of lambs were similar across dietary groups. Fetal plasma concentrations of glucose, insulin and IGF-1 were higher ( P < 0.05) in the blood of fetuses from OB than C ewes. Total AMPK and phosphorylated AMPK at Thr 172 (the active form) were reduced ( P < 0.05) by 19.7 ± 8.4% and 25.9 ± 7.7%, respectively in the COT arterial tissues of OB ewes. Total acetyl-CoA carboxylase (ACC), a down-stream target of AMPK, and its phosphorylated form were also reduced ( P < 0.05) by 32.9 ± 9.2% and 45.4 ± 14.6%, respectively. The phosphorylation of IRS-1 at Ser 789, a site phosphorylated by AMPK, was 24.5 ± 9.0% lower ( P < 0.05) in COT arteries of OB than C ewes. No alteration in total insulin receptor, total IGF-1 receptor or their phosphorylated forms was observed, down-stream insulin signaling was down-regulated in COT arteries of OB ewes, which may have resulted in the observed decrease in COT vascular development in OB ewes.

Villitis of Unknown Etiology Is Associated with a Distinct Pattern of Chemokine Up-Regulation in the Feto-Maternal and Placental Compartments: Implications for Conjoint Maternal Allograft Rejection and Maternal Anti-Fetal Graft-versus-Host Disease

The co-presence of histoincompatible fetal and maternal cells is a characteristic of human placental inflammation. Villitis of unknown etiology (VUE), a destructive inflammatory lesion of villous placenta, is characterized by participation of Hofbauer cells (placental macrophages) and maternal T cells. In contrast to acute chorioamnionitis of infection-related origin, the fundamental immunopathology of VUE is unknown. This study was performed to investigate the placental transcriptome of VUE and to determine whether VUE is associated with systemic maternal and/or fetal inflammatory response(s). Comparison of the transcriptome between term placentas without and with VUE revealed differential expression of 206 genes associated with pathways related to immune response. The mRNA expression of a subset of chemokines and their receptors (CXCL9, CXCL10, CXCL11, CXCL13, CCL4, CCL5, CXCR3, CCR5) was higher in VUE placentas than in normal placentas (p < 0.05). Analysis of blood cell mRNA showed a higher expression of CXCL9 and CXCL13 in the mother, and CXCL11 and CXCL13 in the fetus of VUE cases (p < 0.05). The median concentrations of CXCL9, CXCL10, and CXCL11 in maternal and fetal plasma were higher in VUE (p < 0.05). Comparison of preterm cases without and with acute chorioamnionitis revealed elevated CXCL9, CXCL10, CXCL11, and CXCL13 concentrations in fetal plasma (p < 0.05), but not in maternal plasma with chorioamnionitis. We report for the first time the placental transcriptome of VUE. A systemic derangement of CXC chemokines in maternal and fetal circulation distinguishes VUE from acute chorioamnionitis. We propose that VUE be a unique state combining maternal allograft rejection and maternal antifetal graft-vs-host disease mechanisms.

Kinetics of selected di- n-butyl phthalate metabolites and fetal testosterone following repeated and single administration in pregnant rats

Human exposure to phthalic acid diesters occurs through a variety of pathways as a result of their widespread use in consumer products and plastics. Repeated doses of di- n-butyl phthalate (DBP) from gestation day (GD) 12 to 19 disrupt testosterone synthesis and male sexual development in the fetal rat. Currently little is known about the disposition of DBP metabolites, such as monobutyl phthalate (MBP) and its glucuronide conjugate (MBP-G), during gestation after repeated exposure to DBP. In order to gain a better understanding of the effect of repeated dosing on maternal and fetal metabolism and distribution, pregnant Sprague–Dawley rats were given a single dose of 500 mg/kg DBP on GD 19 or daily doses of 50, 100, and 500 mg/(kg day) from GD 12 to 19 via corn oil gavage. Dose–response evaluation revealed a non-linear increase in maternal and fetal plasma concentrations of MBP. Maternal and fetal MBP levels were slightly lower in animals after 8 days of dosing at 500 mg/(kg day). Fetal plasma MBP levels closely followed maternal plasma, while the appearance and elimination of MBP-G in fetal plasma were significantly delayed. MBP-G accumulated over time in the amniotic fluid. Inhibition of testosterone was rapid in fetal testes when exposed to DBP (500 mg/(kg day)) on GD 19. Within 24 h, the level of inhibition in the fetus was similar between animals exposed to a single or multiple daily doses of 500 mg/(kg day). Examination of testosterone time-course data indicates a rapid recovery to normal levels within 24 h post-dosing at DBP doses of 50 and 100 mg/(kg day), with a rebound to higher than normal concentrations at later time-points. MBP kinetics in fetal testes allows direct comparison of active metabolite concentrations and testosterone response in the fetal testes.

Increased Fetal Plasma and Amniotic Fluid Erythropoietin Concentrations: Markers of Intrauterine Hypoxia

Tissue hypoxia is the major stimulus of erythropoietin (EPO) synthesis in fetuses and adults. Since EPO does not cross the placenta and is not stored, fetal plasma and amniotic fluid levels indicate EPO synthesis and elimination. Acutely, the rate and magnitude of the increase in plasma EPO levels correlate with the intensity of hypoxia. Amniotic fluid EPO levels correlate with cord plasma levels in normal and abnormal pregnancies, with fetal plasma EPO levels in humans averaging 2.6 times higher than the corresponding amniotic fluid EPO levels. Recent experimental and clinical studies demonstrate that EPO has neuroprotective effects related to its anti-apoptotic and vascular growth-promoting properties. Although under basal conditions the fetal kidneys are the main site of EPO production, during hypoxia recent experimental data indicate an important role of the placenta. Amniotic fluid EPO levels have been shown to increase exponentially during fetal hypoxia in preeclamptic, diabetic and Rh-immunized pregnancies, to correlate inversely with cord blood pH, pO₂ and base excess and to predict neonatal morbidities and NICU admission. As an indicator of chronic intrauterine hypoxia, fetal EPO measurements have increased our knowledge about the pathogenesis and importance of intrauterine growth restriction, macrosomia, diabetic pregnancy, prolonged pregnancy, meconium staining, fetal hemorrhage, fetal anemia, maternal smoking and alcohol consumption, abnormal fetal heart rate and abnormal Doppler flow patterns. While the clinical utility of fetal amniotic fluid and plasma EPO measurements in the management of high-risk pregnancies and their offspring is promising, adequately powered clinical trials are urgently needed.

Relationship between Cardiofemoral Index and the plasma concentration of brain natriuretic peptide in anemic fetuses associated with Rh alloimmunization

Fetal anemia is a common result of alloimmunization and is an important cause of fetal congestive heart failure resulting in heart dilation. Fetuses suspected of having heart failure present a higher Cardiofemoral Index and an increase in plasma BNP levels, because the cardiac hormonal system is activated by increased heart wall stretch due to increased left ventricular volume and pressure overload. Our group studied 33 pregnant women (22-31 weeks' gestation at the first cordocentesis) referred for intrauterine fetal transfusion due to severe red blood cells isoimmunization. Up to 6 h prior to each cordocentesis, all fetuses were submitted to ultrasonography measurements where the Cardiofemoral Index was calculated. Samples of blood from the umbilical vein were collected for hemoglobin concentration and blood gas measurements. Plasma levels of BNP were determined with the use of plasma that had previously been frozen and thawed once. Plasma BNP was measured by radioimmunoassay. Pearson's correlation test and regression analysis were used to determine the association between the plasma concentration of BNP and the Cardiofemoral Index of the anemic fetuses with RH alloimmunization. Anemia was severe in 17 (50%) fetuses, mild in 9 (26.47%) and in 8 patients (23.53%) the fetuses were not anemic; hemoglobin ranged from 3.10 to 15.70 g/dl. The Cardiofemoral Index ranged from 0.43 to 0.87 and it was altered (>or=0.59) in 23 fetuses. A significant positive correlation was observed between BNP plasma fetal concentration and Cardiofemoral Index (Pearson r=0.61, P<0.0001). These results suggest that fetal plasma concentration of BNP may increase in fetuses with heart dilation leading to a positive association between Cardiofemoral Index and plasma concentration of BNP.

Is Metabolic Syndrome X a Disorder of the Brain?

Abdominal obesity, atheroslcerosis, insulin resistance, hyperlipidemias, hypertension, and type 2 diabetes mellitus are important components of metabolic syndrome X. An increase in pro-inflammatory cytokines, decrease in the concentrations of endothelial nitric oxide (eNO) and adiponectin, and an alteration in hypothalamic peptides that control satiety, hunger, and food intake have been reported in metabolic syndrome X. Although when and how metabolic syndrome X is initiated is not clear, there is evidence to suggest that increased consumption of high-energy diet, saturated and trans-fats by pregnant women and lactating mothers could trigger changes in the concentrations of long-chain polyunsaturated fatty acids (LCPUFAs) in maternal and fetal plasma and tissues. LCPUFAs have a modulatory influence on neuronal growth, maturation and synapse formation; influence the actions of hypothalamic peptides, neuropeptides, leptin, adiponectin, and various cytokines, especially during the perinatal period. In addition, LCPUFAs function as endogenous inhibitors of HMG-CoA reductase and ACE (angiotensin converting enzyme), augment eNO synthesis, modulate vascular tone, and potentiate insulin action both in the peripheral tissues and brain. Hence, sub-optimal maternal and fetal plasma and tissue concentrations of LCPUFAs increase pro-inflammatory cytokine levels that could trigger the development of metabolic syndrome X in those children who have a genetic predisposition, and continue to take highenergy diet, and saturated and trans-fats. This implies that perinatal interventions in the form of adequate supplementation of LCPUFAs could be of significant benefit in the prevention of metabolic syndrome X. Preliminary evidence suggests that supplementation of LCPUFAs can restore the levels of hypothalamic peptides to normal. In addition, weight loss due to Roux-en-gastric bypass procedure done in diet-induced obese animals decreased inflammation, restored hypothalamic “body weight/ appetite/ satiety set point” by restoring hypothalamic neuropeptides to normal, suggesting a cross talk between gastrointestinal hormones and hypothalamus. These evidences suggest that metabolic syndrome X occurs in a genetically predisposed subject as a result of interaction(s) between hypothalamic peptides, gastrointestinal tract, cytokines, nutrition, and life style factors. Keywords: Metabolic syndrome X, cytokines, leptin, nutrition, exercise, hypothalamus, serotonin, dopamine, neuropeptide Y, melanocyte stimulating hormone

Effect of Variable Long-Term Maternal Feed Allowance on the Development of the Ovine Placenta and Fetus

Maternal feed allowance during pregnancy can affect the development of the ovine placenta and fetus. The impact of variations in feed allowance prior to as well as throughout pregnancy has received less attention. Ewes were offered 0.6 (R), 1.2 (C) or 1.8 (AL) maintenance requirements from 89 days before conception until day 133 of pregnancy. Ewes were euthanased on days 50, 92 and 133 of pregnancy. Ewe live weight and body condition score, maternal and fetal metabolic and hormonal profiles, fetal body dimensions and organ weights, and the number, weight and morphology of placentomes were measured. Maternal live weight and condition score were lower in R compared to AL ewes at all stages of pregnancy ( P < 0.05). Plasma glucose and albumin concentrations of R ewes were significantly reduced ( P < 0.05) at mid and late gestation, respectively. Placental components were generally unresponsive to long term variations in maternal feed allowance. However, placental weight was significantly ( P < 0.05) correlated with fetal weight at days 50 ( r = 0.59) and 133 ( r = 0.69) of gestation. By late gestation growth-retarded singleton fetuses from R ewes were 19% lighter ( P < 0.05), with reduced abdominal (9%) and thoracic (10%) girths ( P<0.05) but of similar crown-rump length compared with fetuses from AL ewes. These differences were associated with significantly reduced IGF-I concentrations in fetal plasma ( P < 0.05). In conclusion, maternal, placental and fetal adaptations to long established planes of variable maternal feed allowance were able to maintain fetal growth during early and mid-pregnancy while fetal growth restriction, associated with reduced fetal IGF-I levels, became apparent in late pregnancy.

Effect of controlled alterations in maternal dietary retinol on foetal and neonatal retinol status and pregnancy outcome in pigs

The objective of this experiment was to examine the effects of feeding a vitamin A deficient diet (VAF) to pigs at different times on day 100 of foetal and days 0, 1 and 2 of neonatal development. Three treatments included a control ( n = 12), VAF for 100 days before mating and during the first month of pregnancy ( n = 13; VAF–control), and VAF during the oestrous cycle before mating and throughout pregnancy ( n = 13; control–VAF). On day 100 of pregnancy, maternal liver and plasma retinol concentrations were reduced in both groups of gilts fed a vitamin A free diet compared to controls ( P < 0.001 and P < 0.01, respectively). Day 100 foetal liver retinol concentrations were not affected by dietary treatment, whereas foetal plasma concentrations were higher in foetuses carried by gilts fed the VAF–control diet ( P < 0.05). Piglets born to mothers fed the control–VAF, but not the VAF–control diet had consistently lower hepatic and plasma liver retinol concentrations ( P < 0.05). Moderate reductions in maternal vitamin A at either stage of pregnancy did not affect pregnancy rate, litter size, progesterone secretion or the allometric relationships between foetal or neonatal organ and total body size. Reduced vitamin A during conception and early pregnancy, but not during later pregnancy, was associated with increased within-litter uniformity in birth weight ( P < 0.05) and a tendency for fewer low birth weight piglets, but this needs to be confirmed in a greater number of sows. The mechanism underlying this effect is not known, but appears to not involve an alteration in progesterone production.

Coffee Inhibits the Glucuronidation of 1-Naphthol in Rat Syncytiotrophoblast Cells

The placenta acts as a barrier that protects the fetus from xenobiotics in the maternal blood. Phase II conjugation reactions in the placenta are considered to play an important role in this protective process by transferring polar hydroxyl groups and thereby imparting water solubility that facilitates the excretion of xenobiotics. Since coffee consumption during pregnancy is reported to affect fetal growth and development, we examined its effects upon the conjugation reactions in the rat syncytiotrophoblast cell line TR-TBT 18d-1. We detected a high level of glucuronidation for 1-naphthol, a model compound, in both a dose- and culture time-dependent manner in the TR-TBT 18d-1 cells. However, no sulfation was detected in any of our analyses. Coffee was found to inhibit the glucuronidation of 1-naphthol with an IC50 of 4.5% (v/v). In contrast however, caffeine, which is a major bioactive constituent of coffee, did not show any inhibition at doses of up to 100 μM. Coffee was also found to inhibit UDP-glucuronosyl transferase (UGT) activity towards 1-naphthol in vitro to a similar extent [IC50=1.5% (v/v)] as in intact cells. Moreover, the expression of the UGT 1A6, which is known to mainly catalyze the glucuronidation of 1-naphthol, was not affected by coffee. If coffee inhibits placental glucuronidation during pregnancy, its consumption would increase the fetal plasma concentrations of harmful xenobiotics, potentially affecting normal fetal growth and development.

Baggs ewes adapt to maternal undernutrition and maintain conceptus growth by maintaining fetal plasma concentrations of amino acids1

Adequate delivery of AA is essential for normal fetal growth and development. Recently, we reported that when ewes from the University of Wyoming flock (farm flock with adequate nutrition) were fed 50% (nutrient-restricted) or 100% (control-fed) of the NRC-recommended nutrient requirements between d 28 and 78 of gestation, fetal weights as well as concentrations of most AA in maternal and fetal blood were substantially reduced in nutrient-restricted vs. control-fed pregnancies. The current study utilized Baggs ewes, which were selected under a markedly different production system (range flock with limited nutrition), to test the hypothesis that adaptation of ewes to nutritional and environmental changes may alter placental efficiency and conceptus nutrient availability in the face of maternal nutrient restriction. Baggs ewes received 50 or 100% of the NRC nutrient requirements between d 28 and 78 of pregnancy. On d 78, maternal uterine arterial and fetal umbilical venous blood samples were obtained, and the ewes were euthanized. Amino acids and their metabolites (ammonia, urea, and polyamines) in plasma were analyzed using enzymatic and HPLC methods. The results showed that maternal plasma concentrations of 9 AA (Asp, Ile, Leu, Lys, Orn, Phe, Thr, Trp, and Val) as well as maternal and fetal plasma concentrations of ammonia and urea were reduced (P < 0.05) in nutrient-restricted compared with control-fed Baggs ewes. However, fetal plasma concentrations of all AA and polyamines did not differ (P = 0.842) between the 2 groups of ewes. Collectively, these findings suggest that Baggs ewes, by adapting to the harsh conditions and limited nutrition under which they were selected, were able to maintain fetal concentrations of AA in the face of a maternal nutrient restriction through augmenting placental efficiency.

Blockade of Estrogen Receptors Decreases CNS and Pituitary Prostaglandin Synthase Expression in Fetal Sheep

Background/Aims: Both prostaglandin E₂ (PGE₂) and estradiol stimulate fetal ACTH secretion and augment fetal ACTH responses to stress. We have reported that estradiol increases prostaglandin endoperoxide synthase-2 (PGHS-2), and we have proposed that there is a positive feedback relationship between estrogen and fetal hypothalamus-pituitary-adrenal (HPA) axis activity that is dependent upon PGHS activity in the fetal brain. The present study was designed to test the hypothesis that blockade of estrogen receptors in the fetal brain decrease PGHS-2 expression and reduces fetal HPA axis activity. Methods: In study 1, six time-dated pregnant ewes with chronically-catheterized twin fetuses were used. In each pregnancy, one twin was treated intracerebroventricularly (icv) with the estrogen receptor antagonist ICI 182,780 (25 µg/day; n = 6) while the other twin served as an age-matched control. In study 2, plasma samples were drawn from 10 singleton chronically-catheterized fetuses on alternating days until the time of spontaneous parturition. Results: ICI infusion caused significantly decreased PGHS-2 mRNA abundance in fetal central nervous system and pituitary, with the greatest decreases occurring in hippocampus and pituitary. There were no statistically significant changes in PGHS-1 mRNA. ICI infusion did not significantly change fetal plasma concentrations of pro-opiomelanocortin (POMC), ACTH, or cortisol in fetuses 130–134 days ges- tation (study 1) but did decrease the preparturient rise in plasma pro-opiomelanocortin concentrations in study 2. Conclusion: We conclude that PGHS-2 expression in the late-gestation fetal brain is in part stimulated by circulating estrogens in fetal plasma. Blockade of CNS estrogen receptors reduces preparturient plasma concentrations of POMC, but does not reduce fetal HPA axis activity in 130–134 day fetal sheep.

N‐terminal parathyroid hormone‐related protein levels in human intrauterine growth restricted pregnancies

N-terminal parathyroid hormone-related protein has a vital role in regulating cell growth and differentiation, uteroplacental vasodilatation, uterine muscle relaxation, and placental transport. These functions are compromised in intrauterine growth restriction. We aimed to investigate N-terminal parathyroid hormone-related protein concentrations in maternal, fetal, and neonatal plasma of intrauterine-growth-restricted and appropriate for gestational age pregnancies. Plasma N-terminal parathyroid hormone-related protein levels were determined in 40 mothers and their 20 intrauterine-growth-restricted and 20 appropriate for gestational age singleton full-term fetuses and neonates on postnatal days 1 and 4. Fetal N-terminal parathyroid hormone-related protein levels were significantly lower in the intrauterine growth restriction group (b=1.166, 95%CI: 0.430-1.902, p=0.003) and correlated with the customized centiles of the infants (r=0.407, p=0.009). In the appropriate for gestational age group, neonatal day 1 N-terminal parathyroid hormone-related protein levels were significantly lower compared to maternal (p<0.001) and fetal (p=0.022) ones. Fetal and neonatal day 1 levels were significantly lower in males (b=-1.303, 95%CI: -2.508 to -0.097, p=0.036, and b=-0.802, 95%CI: -1.5 to -0.105, p=0.027, respectively). In the intrauterine growth restriction group, maternal N-terminal parathyroid hormone-related protein levels were significantly increased compared to fetal (p<0.001) and neonatal day 1 (p=0.001) levels. The reduced fetal N-terminal parathyroid hormone-related protein concentrations in intrauterine growth restriction may reflect compromised placental function and impaired fetal growth, suggesting that N-terminal parathyroid hormone-related protein may be involved in the pathogenesis of intrauterine growth restriction.

The insulin-like growth factor system and the fetal brain: Effects of poor maternal nutrition

The insulin-like growth factor (IGF) signaling system plays indispensable roles in pre- and post-natal brain growth and development. A large body of studies using both in vivo null mutant and transgenic mice and in vitro neuronal culture techniques indicate that IGF-I acts directly on the brain while IGF-II effects are mediated to a large extent by IGF-II control of placental growth. It appears that all of the mechanisms, except migration, that are involved in normal brain development, e.g., proliferation, apoptosis, maturation and differentiation, are influenced by IGF-I. While IGF system members are produced in the brain, recent reports in post-natal animals indicate that normal brain health and function are dependent upon transfer of circulating IGF-I from the liver and its transfer across the blood brain barrier. Data showing that this phenomenon applies to pre-natal brain growth and development would make an important contribution to fetal physiology. A number of kinase pathways are able to participate in IGF signaling in brain with respect to nutrient restriction; among the most important are the PI3K/AKT, Ras-Raf-MEK-ERK and mTOR-nutrient sensing pathways. Both maternal and fetal IGF-I peripheral plasma concentrations are greatly reduced in nutrient restriction while IGF-II does not appear to be affected. Nutrient restriction also affects IGF binding protein concentrations while effects on the IGF-I receptor appear to vary with the paradigm. Studies on the effects of nutrient restriction on the fetal primate brain in relation to activity of the IGF system are needed to determine the applicability of rodent studies to humans.

INTRAVENOUS ADMINISTRATION OF ARGININE OR CITRULLINE INCREASED PLASMA CONCENTRATIONS OF ARGININE IN PREGNANT EWES

Functional capacity of the placenta is modulated by complex biological and environmental factors that ultimately influence growth rate of the fetus. In sheep, placental vascular formation and function change dynamically throughout pregnancy, allowing for an increase in uterine and umbilical blood flows to accommodate increasing fetal metabolic demands. Therefore, factors that affect maternal and placental blood flows (vasodilation and angiogenesis) can influence development of the fetus. Nitric oxide regulates fetoplacental blood flow during normal pregnancy and is derived from arginine. Arginine is synthesized from citrulline in virtually all mammalian cell types. We hypothesized that parenteral provision of arginine or citrulline may be an effective means of increasing arginine availability in maternal and fetal plasma to enhance pregnancy outcomes in pregnant ewes. On gestational day 130±5, maternal and fetal catheters were advanced from the femoral artery and vein into the abdominal aorta and vena cava, respectively, in crossbred ewes (n=5). After a recovery period of at least 5 days, all ewes received a bolus intravenous dose of arginine (27 mg/kg body wt) on the first day and the same dose of citrulline on the subsequent day. Maternal and fetal arterial blood samples (1 ml) were obtained simultaneously at −120, −60, 0, 5, 15, 30, 60, 120, 180 and 240 min from time of delivery of the bolus intravenous dose of arginine or citrulline. Amino acids in plasma were analyzed using HPLC. Pharmacokinetics of administered arginine or citrulline were analyzed using the single exponential model. Compared with the baseline value, concentrations of arginine in maternal plasma increased by 308%, 170%, 122%, 72%, 44%, and 11% at 5, 15, 30, 60, 120, and 180 min after its dosing, respectively (P<0.05). The arginine administration increased its concentration in fetal plasma by 21% at 180 min in comparison with the baseline value (P<0.05). Compared with the baseline value, concentrations of citrulline in maternal plasma increased by 349%, 268%, 187%, 109%, 89%, 71%, and 57% at 5, 15, 30, 60, 120, and 180 min after its administration, respectively (P<0.05). The citrulline administration also increased (P<0.05) its concentrations in fetal plasma by 13%, 18%, and 29%, respectively, at 15, 30, and 60 min and arginine concentrations in maternal plasma by approximately 18% at 15–240 min (P<0.05). The clearance rate was 122% higher (5.49 ± 0.53 vs 2.47 ± 0.25 ml/min per kg), and biological half-life was 50% lower (50 ± 5.6 vs 99 ± 11.8 min), for arginine than for citrulline (P<0.01). These results indicate that, in ewes during late gestation, arginine was cleared from plasma faster than citrulline and that a single intravenous dose of either arginine or citrulline increased arginine concentrations in maternal plasma for 3 or 4 h. (Supported by NIH R21 HD049449) (poster)