Calcitonin gene-related peptide protects from soluble fms-like tyrosine kinase-1-induced vascular dysfunction in a preeclampsia mouse model.

Introduction: Preeclampsia (PE) is a hypertensive disorder during pregnancy associated with elevated levels of soluble FMS-like tyrosine kinase (sFLT-1) and increased vascular sensitivity to angiotensin II (ATII). Calcitonin gene-related peptide (CALCA) is a potent vasodilator that inhibits the ATII-induced increase in blood pressure and protects against ATII-induced increases in oxidative stress through a mitochondrial-dependent pathway in male mice. In rodent pregnancy, CALCA facilitates pregnancy-induced vascular adaptation. Most of the vascular effects of CALCA are mediated by vascular smooth muscle cells (VSMCs). We recently reported that CALCA treatment inhibits sFLT-1-induced decreases in cAMP synthesis in omental artery smooth muscle cells (OASMCs) isolated from pregnant women and has relaxant effects in omental arteries (OAs) isolated from pregnant women with preeclamptic (PE) pregnancies. The current study was designed to assess the effects of sFLT-1 on mitochondrial bioenergetics in OASMCs isolated from pregnant women in the presence or absence of CALCA and assess the development of vascular dysfunction in sFLT-1 using a mouse model of PE pregnancy. Methods: OASMCs were isolated from pregnant women to assess the effects of sFLT-1 on mitochondrial bioenergetics and oxidative stress using the Seahorse assay and quantitative PCR. Pregnant mice overexpressing sFLT-1 via adenoviral delivery were used to assess the effects of CALCA infusion on the sFLT-1-induced increase in blood pressure, ATII hypersensitivity, fetal growth restriction, and the elevated albumin-creatinine ratio. Systemic blood pressure was recorded in conscious, freely moving mice using implantable radio telemetry devices. Results: CALCA inhibited the following sFLT-1-induced effects: 1) increased oxidative stress and the decreased oxygen consumption rate (OCR) in response to maximal respiration and ATP synthesis; 2) increases in the expression of mitochondrial enzyme complexes in OASMCs; 3) increased mitochondrial fragmentation in OASMCs; 4) decreased expression of mitophagy-associated PINK1 and DRAM1 mRNA expression in OASMCs; and 5) increased blood pressure, ATII hypersensitivity, fetal growth restriction, and the albumin-creatinine ratio in sFLT-1-overexpressing pregnant mice. Conclusion: CALCA inhibits sFLT-1-induced alterations in mitochondrial bioenergetics in vascular smooth muscle cells and development of maternal vascular dysfunction in a mouse model of PE.

Low Protein Programming Causes Increased Mitochondrial Fusion and Decreased Oxygen Consumption in the Hepatocytes of Female Rats.

The liver is one of the major organs involved in the regulation of glucose and lipid homeostasis. The effectiveness of metabolic activity in hepatocytes is determined by the quality and quantity of its mitochondria. Mitochondrial function is complex, and they act via various dynamic networks, which rapidly adapt to changes in the cellular milieu. Our present study aims to investigate the effects of low protein programming on the structure and function of mitochondria in the hepatocytes of adult females. Pregnant rats were fed with a control or isocaloric low-protein diet from gestational day 4 until delivery. A normal laboratory chow was given to all dams after delivery and to pups after weaning. The rats were euthanized at 4 months of age and the livers were collected from female offspring for investigating the mitochondrial structure, mtDNA copy number, mRNA, and proteins expression of genes associated with mitochondrial function. Primary hepatocytes were isolated and used for the analysis of the mitochondrial bioenergetics profiles. The mitochondrial ultrastructure showed that the in utero low-protein diet exposure led to increased mitochondrial fusion. Accordingly, there was an increase in the mRNA and protein levels of the mitochondrial fusion gene Opa1 and mitochondrial biogenesis genes Pgc1a and Essra, but Fis1, a fission gene, was downregulated. Low protein programming also impaired the mitochondrial function of the hepatocytes with a decrease in basal respiration ATP-linked respiration and proton leak. In summary, the present study suggests that the hepatic mitochondrial dysfunction induced by an in utero low protein diet might be a potential mechanism linking glucose intolerance and insulin resistance in adult offspring.

Role of adrenomedullin2/ intermedin in pregnancy induced vascular and metabolic adaptation in mice.

Introduction: Adrenomedullin2 (AM2) shares its receptor with Calcitonin gene related peptide and adrenomedullin with overlapping but distinct biological functions. Goal of this study was to assess the specific role of Adrenomedullin2 (AM2) in pregnancy induced vascular and metabolic adaptation using AM2 knockout mice (AM2 -/-). Method : The AM2 -/- mice were successfully generated using Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Nuclease Cas nine system. Phenotype of pregnant AM2 -/- mice was assessed with respect to its fertility, blood pressure regulation, vascular health and metabolic adaptations and compared to the wild type littermates (AM2 +/+). Results : Current data shows that AM2 -/- females are fertile with no significant difference in number of pups/litter compared to the AM2 +/+. However, ablation of AM2 decreases the gestational length and the total number of pups born dead or that die after birth is greater in AM2 -/- mice compared to AM2 +/+ mice (p < 0.05). Further AM2 -/- mice exhibit elevated blood pressure and elevated vascular sensitivity for the contractile responses to angiotensin two and higher serum sFLT-1 trigylcerides levels compared to AM2 +/+(p < 0.05). In addition, AM2 -/- mice develop glucose intolerance with elevated serum levels of Insulin during pregnancy compared to the AM2 +/+mice. Discussion: Current data suggests a physiological role for AM2 in pregnancy induced vascular and metabolic adaptations in mice.

Lipid dysfunction and adrenomedullin expression in omental versus subcutaneous adipose tissues in diabetic pregnancies.

Gestational diabetes mellitus (GDM) is one of the most common complications of pregnancy but the underlying mechanism remains obscure. The aims of this study are to examine if omental adipose tissue (OMAT) and subcutaneous AT (SCAT) differentially express proinflammatory and lipid metabolic adipokines, and if so, whether their regional differences have implications on lipid metabolism in GDM. Paired samples of OMAT and SCAT were excised from pregnant women in scheduled Cesarean sections with non-obese (NOBS), obese (OBS) and GDM. The results showed that the mRNA of monocyte chemoattractant protein (MCP)-1, macrophage marker CD68, and cytokines IL-6, IL-8, and TNF-α are increased in OMAT from GDM women compared to that in NOBS and OBS women (P<0.05). Glucose and TNF-α dose-dependently enhanced ADM and its receptor components CRLR and RAMPs in human adipocytes. Immunofluorescence showed that ADM and its receptor components are higher in OMAT from GDM women compared to non-GDM women. Further, basal lipolysis was greater in OMAT than in SCAT and ADM stimulates further glycerol release in OMAT, but not in SCAT, and these increases are reduced by ADM antagonist, ADM22-52. We therefore conclude that elevated ADM and its receptor expressions by OMAT, but not by SCAT appear to contribute to the lipid dysregulation in GDM women, and manipulation of ADM may represent one of the novel approaches in minimizing the risk of GDM-related fetal overgrowth.

Prenatal Low-Protein Diet Affects Mitochondrial Structure and Function in the Skeletal Muscle of Adult Female Offspring.

Gestational low-protein (LP) diet leads to glucose intolerance and insulin resistance in adult offspring. We had earlier demonstrated that LP programming affects glucose disposal in females. Mitochondrial health is crucial for normal glucose metabolism in skeletal muscle. In this study, we sought to analyze mitochondrial structure, function, and associated genes in skeletal muscles to explore the molecular mechanism of insulin resistance LP-programmed female offspring. On day four of pregnancy, rats were assigned to a control diet containing 20% protein or an isocaloric 6% protein-containing diet. Standard laboratory diet was given to the dams after delivery until the end of weaning and to pups after weaning. Gestational LP diet led to changes in mitochondrial ultrastructure in the gastrocnemius muscles, including a nine-fold increase in the presence of giant mitochondria along with unevenly formed cristae. Further, functional analysis showed that LP programming caused impaired mitochondrial functions. Although the mitochondrial copy number did not show significant changes, key genes involved in mitochondrial structure and function such as Fis1, Opa1, Mfn2, Nrf1, Nrf2, Pgc1b, Cox4b, Esrra, and Vdac were dysregulated. Our study shows that prenatal LP programming induced disruption in mitochondrial ultrastructure and function in the skeletal muscle of female offspring.

Calcitonin Gene Related Peptide, Adrenomedullin, and Adrenomedullin 2 Function in Uterine Artery During Human Pregnancy.

RATIONALE: Calcitonin gene-related peptide (CGRP) and its family members adrenomedullin (ADM) and adrenomedullin 2 (ADM2; also known as intermedin) support vascular adaptions in rat pregnancy. OBJECTIVE: This study aimed to assess the relaxation response of uterine artery (UA) for CGRP, ADM, and ADM2 in nonpregnant and pregnant women and identify the involved mechanisms. FINDINGS: (1) Segments of UA from nonpregnant women that were precontracted with U46619 (1µM) in vitro are insensitive to the hypotensive effects of CGRP, ADM, and ADM2; (2) CGRP, ADM, and ADM2 (0.1-100nM) dose dependently relax UA segments from pregnant women with efficacy for CGRP > ADM = ADM2; (3) the relaxation responses to CGRP, ADM, and ADM2 are differentially affected by the inhibitors of nitric oxide (NO) synthase (L-NAME), adenylyl cyclase (SQ22536), apamin, and charybdotoxin; (4) UA smooth muscle cells (UASMC) express mRNA for calcitonin receptor-like receptor (CRLR) and receptor activity modifying protein (RAMP)1 and RAMP2 but not RAMP3; (5) receptor heterodimer comprising CRLR/RAMP1 and CRLR/RAMP2 but not CRLR/RAMP3 is present in UA; (6) soluble fms-like tyrosine kinase (sFLT-1) and TNF-α treatment decrease the expression of RAMP1 mRNA (P < 0.05) in UASMC; and (7) sFLT-1 treatment impairs the association of CRLR with all 3 peptides while TNF-α inhibits the interaction of CGRP but not ADM or ADM2 with CRLR in UASMC (P < 0.05). CONCLUSIONS: Relaxation sensitivity of UA for CGRP, ADM, and ADM2 is increased during pregnancy via peptide-specific involvement of NO system and endothelium-derived hyperpolarizing factors; vascular disruptors such as sFLT-1 and TNFα adversely impact their receptor system in UASMC.

Soluble fms-like tyrosine kinase-1 and angiotensin2 target calcitonin gene-related peptide family peptides in maternal vascular smooth muscle cells in pregnancy†.

Calcitonin gene-related peptide (CALCB), adrenomedullin (ADM), and adrenomedullin2 (ADM2) are hypotensive peptides that belong to CALCB family of peptides. Goal of this study was to identify the effect of fms-like tyrosine kinase (sFLT-1) and angiotensin2 (Ang2) on the function of these peptides in OA smooth muscle cells (OASMC) and assess the sensitivity of OA for these peptides in preeclampsia (PE) and normotensive pregnancy. METHODS: Peptide function was assessed by Cyclic adenosine monophosphate (cAMP) assays and wire myograph; mRNA expression by Polymerase chain reaction (PCR) and protein-protein interaction by proximity ligation assay and co-immunoprecipitation. FINDINGS: All three peptides increased cAMP synthesis in the order of efficacy CALCB > ADM = ADM2 and vascular endothelial growth factor (VEGF) mRNA in OASMC (P < 0.05); sFLT-1 mediated decrease in cAMP synthesis (P < 0.05) is differentially rescued by all three CALCB family peptides in OASMC (P < 0.005); sFLT-1 decreased receptor activity-modifying protein (RAMP)1 and RAMP2 mRNA expression (P < 0.05); Ang2 decreased the expression of calcitonin-receptor-like receptor and RAMP1 mRNA and desensitized CALCB and ADM2 receptors in OASMC (P < 0.05); sFLT-1 increased RAMP1and Ang2 type 1 receptor (AT1R) interaction in OASMC which is inhibited in presence of all three peptides; and all three peptides relax OA in PE with enhanced ADM2 response (P < 0.05). CONCLUSION: sFLT-1 and Ang2 impair OASMC mediated functional responses of CALCB family peptides which can be inhibited by respective peptide treatment. The sensitivity of OA for CALCB, ADM, and ADM2-mediated relaxation is retained in PE.

In utero low-protein-diet-programmed type 2 diabetes in adult offspring is mediated by sex hormones in rats†.

Sex steroids regulate insulin sensitivity and glucose metabolism. We had characterized a lean type 2 diabetes (T2D) rat model using gestational low-protein (LP) diet programming. Our objective was to identify if endocrine dysfunction leading to decreased sex hormone levels will precede the development of T2D and if steroid replacement will prevent the onset of the disease. Pregnant rats were fed control or isocaloric LP diet from gestational day 4 until delivery. Normal diet was given to all mothers after delivery and to pups after weaning. LP offspring developed glucose intolerance and insulin resistance at 4 months. We measured sex steroid hormone profiles and expression of key genes involved in steroidogenesis in testis and ovary. Furthermore, one-month old rats were implanted with 90-day slow release T and E2 pellets for males and females, respectively. Glucose tolerance test (GTT) and euglycemic hyperinsulinemic clamp was performed at 4 months. LP-programmed T2D males had low T levels and females had low E2 levels due to dysregulated gene expression during steroidogenesis in gonads. GTT and euglycemic hyperinsulinemic clamp showed that LP males and females were glucose intolerant and insulin resistant; however, steroid supplementation prevented the onset of glucose intolerance and insulin resistance. Rats that developed T2D by LP programming have compromised gonadal steroidogenesis leading to low T and E2 in males and females, respectively. Sex steroid supplementation prevented the onset of glucose intolerance and insulin resistance indicating low sex steroid levels could cause compromised glucose metabolism ultimately leading to T2D.

Adipose Tissue Inflammation and Adrenomedullin Overexpression Contribute to Lipid Dysregulation in Diabetic Pregnancies.

Context: Impaired maternal lipid metabolism in gestational diabetes mellitus (GDM) has detrimental effects on maternal health and fetal growth. We previously reported the excessive expression of adrenomedullin (ADM) and its receptors in GDM adipose tissues compared with normal glucose-tolerant pregnancies. In the present study, we determined the mechanisms underlying enhanced expression of ADM and its receptors. Design: Omental adipose tissue (OAT) samples were collected from women during cesarian section of term pregnancy with nonoverweight (NOW; n = 9), overweight (OW; n = 8), obese (OBS; n = 10), and GDM (n = 10) status. Results: The expression of ADM and its receptors was greater in OATs from GDM than from women who were NOW, OW, and OBS. The expression of adipokines, leptin, and resistin were significantly increased, but adiponectin was decreased in OATs from patients with GDM compared with those without GDM. Macrophage infiltration and TNF-α expression were greater in OAT from pregnant women with GDM than in pregnant women without GDM. Furthermore, TNF-α dose dependently increased mRNA for ADM and its receptor components calcitonin receptor-like receptor and receptor activity-modifying proteins 2 and 3 in OAT explants from women who were NOW. Human adipocytes treated with ADM significantly increased glycerol release in culture medium, and the increases of glycerol in culture medium of OAT from women with GDM were attenuated by ADM antagonists, ADM22-52. Conclusions: Increased macrophage infiltration and TNF-α expression in adipose tissue from GDM, but not from OBS, tissues stimulate ADM and its receptor overexpression, leading to enhanced lipolysis and hyperlipidemia. This might contribute to fetal macrosomia and adiposity in diabetic pregnancies.

The Citrulline Recycling Pathway Sustains Cardiovascular Function in Arginine-Depleted Healthy Mice, but Cannot Sustain Nitric Oxide Production during Endotoxin Challenge.

Background: The recycling of citrulline by argininosuccinate synthase 1 (ASS1) and argininosuccinate lyase (ASL) is crucial to maintain arginine availability and nitric oxide (NO) production. Pegylated arginine deiminase (ADI-PEG20) is a bacterial enzyme used to deplete circulating arginine. Objective: The goal of this research was to test the hypothesis that citrulline is able to sustain intracellular arginine availability for NO production in ADI-PEG20 arginine-depleted mice. Methods: Six- to 8-wk-old male C57BL/6J mice injected with ADI-PEG20 (5 IU) or saline (control) were used in 4 different studies. Arginine, citrulline, and NO kinetics were determined by using stable isotopes in unchallenged (study 1) and endotoxin-challenged (study 2) mice. Blood pressure was determined by telemetry for 6 d after ADI-PEG20 administration (study 3), and vasomotor activity and ASS1 and ASL gene expression were determined in mesenteric arteries collected from additional mice (study 4). Results: ADI-PEG20 administration resulted in arginine depletion (<1 compared with 111 ± 37 µmol/L) but in greater plasma citrulline concentrations (900 ± 123 compared with 76 ± 8 µmol/L; P < 0.001) and fluxes (402 ± 17 compared with 126 ± 4 µmol ⋅ kg-1 ⋅ h-1; P < 0.001) compared with controls. Endotoxin-challenged ADI-PEG20-treated mice produced less NO than controls (13 ± 1 compared with 27 ± 2 µmol ⋅ kg-1 ⋅ h-1; P < 0.001). No differences (P > 0.50) were observed for cardiovascular variables (heart rate, blood pressure) between ADI-PEG20-treated and control mice. Furthermore, no ex vivo vasomotor differences were observed between the 2 treatments. ADI-PEG20 administration resulted in greater gene expression of ASS1 (∼3-fold) but lower expression of ASL (-30%). Conclusion: ADI-PEG20 successfully depleted circulating arginine without any effect on cardiovascular endpoints in healthy mice but limited NO production after endotoxin challenge. Therefore, the citrulline recycling pathway can sustain local arginine availability independently from circulating arginine, satisfying the demand of arginine for endothelial NO production; however, it is unable to do so when a high demand for arginine is elicited by endotoxin.

Targeting Adrenomedullin to Improve Lipid Homeostasis in Diabetic Pregnancies.

Context: Gestational diabetes mellitus (GDM) is associated with disturbances in maternal lipid metabolism. Hypertriacylglycerolemia in GDM is associated with an increased risk of large for gestational age neonates, but the pathogenesis of disrupted lipid homeostasis remains unclear. Objectives: To determine the role of adrenomedullin (AM), a multifunctional peptide, in lipid metabolism in GDM. Design: Omental adipose biopsies were collected in term pregnancy from women with normal glucose tolerance (NGT, n = 10) and GDM (n = 10). Results: AM and its receptor components, calcitonin receptor-like receptor, receptor activity-modifying protein 2, and receptor activity-modifying protein 3, were higher in adipose tissues from GDM compared with NGT pregnancies, and these expressions in normal adipose tissues were enhanced by glucose and tumor necrosis factor-αin vitro. AM dose- and time-dependently stimulated lipolysis in human adipocytes, and this effect was reversed by AM antagonist AM22-52. Furthermore, AM inhibited phosphorylation of insulin receptor-ß and insulin receptor substrate-1 and enhanced the protein expression of leptin and resistin in adipose tissue from NGT women. The increased messenger RNA expression of leptin and resistin in adipose tissue from GDM was reduced by AM22-52 treatment. Conclusions: GDM pregnancies are associated with increased AM and its receptor expression in adipose tissues. AM stimulates lipolysis and leptin and resistin expression, and these effects can be reversed by AM antagonist. To our knowledge, manipulation of AM and its receptors in adipocytes might represent an approach in reducing the risk of GDM and fetal overgrowth.

Impaired Vasodilatory Responses of Omental Arteries to CGRP Family Peptides in Pregnancies Complicated by Fetal Growth Restriction.

RATIONALE: Calcitonin gene-related peptide (CGRP), adrenomedullin (ADM), and adrenomedullin2 (ADM2)/intermedin are potent vasorelaxant peptides considered to play a role in the adaptive mechanisms in rat pregnancy through increased vasodilation in mesenteric and uterine artery. OBJECTIVE: This study was designed to demonstrate the response of omental arteries (OA) to vasoactive peptides CGRP, ADM, and ADM2 in pregnancy complications such as fetal growth restriction (FGR), and assess the changes in the expression of their receptor components in segments of OA from FGR pregnancy compared to the control. FINDINGS: The findings for this study are: 1) relaxation responses of OA were higher for bradykinin (78.55 ± 3.91 vs 52.67 ± 2.19; P < .05) in pregnancy with FGR compared to the normal, 2) relaxation response of OA segments to CGRP was similar with no change in the expression of G-protein couple receptor-calcitonin receptor-like receptor complex in normal healthy pregnancy and pregnancy complicated by FGR, 3) maximal relaxation response of OA were significantly (P < .05) lower for both ADM (18.2 ± 6.7 vs 38 ± 2.5) and ADM2 (26.9 ± 6.7 vs 48 ± 2.6) along with decreases in their respective ligand-receptor complex in FGR compared to the normal pregnancies, 4) expression of calcitonin receptor-like receptor mRNA was higher but its immunoreactivity was lower in OA from FGR pregnancy compared to the normal, and 5) mRNA and protein levels of RAMP1, RAMP2, and RAMP3 were lower in OA isolated from FGR pregnancies compared to the normal. CONCLUSION: The current study demonstrates that FGR is associated with an increase in the sensitivity of OA to bradykinin and decreased sensitivity for ADM and ADM2 ligand-receptor system with no change in the response for CGRP compared to the normal healthy pregnancy, and suggests a potential role for ADM and ADM2 in the pathophysiology of maternal vasculature in FGR pregnancy.

Pregnancy Increases Relaxation in Human Omental Arteries to the CGRP Family of Peptides.

Calcitonin gene-related peptide (CALCB) and its family members adrenomedullin (ADM) and intermedin (ADM2) play important roles in maintaining vascular adaptations during pregnancy in animal models. The present study was designed to evaluate the responses of omental arteries to CALCB, ADM, and ADM2 in pregnant and nonpregnant women, and to determine the mechanisms involved. By using resistance omental arteries collected from nonpregnant women (n = 15) during laparotomy and from term pregnant women (n = 15) at cesarean delivery, this study shows that the receptor components--calcitonin receptor-like receptor (CALCRL) and receptor activity-modifying proteins (RAMPs) 1, 2 and 3--are localized to endothelial and smooth muscle cells in omental arteries, with increased expressions of both mRNA and protein in pregnant compared with nonpregnant women. The myography study demonstrated that CALCB, ADM, and ADM2 (0.1-100 nM) dose dependently relax U46619 (1 muM) precontracted omental artery segments, and the maximum possible effects to CALCB and ADM2, but not to ADM, are significantly enhanced in pregnant compared with nonpregnant women. Further, the vasodilatory responses to CALCB, ADM, and ADM2 are reduced by inhibitors of nitric oxide (NO) synthase (L-NAME), adenylyl cyclase (SQ22536), voltage-activated potassium channels (4-aminopyrodin and tetrabutylammonium), Ca(2+)-activated potassium channel (charybdotoxin), and cyclooxygenase (indomethacin). In conclusion, the CALCB family of peptides, CALCB and ADM2, increase human omental artery relaxation during pregnancy through diverse mechanisms, including NO, endothelium-derived hyperpolarizing factors (EDHFs) and prostaglandins, and thus could contribute to the vascular adaptations during pregnancy in the human.

L-arginine prevents hypoxia-induced vasoconstriction in dual-perfused human placental cotyledons.

INTRODUCTION: Chronic hypoxia in the uteroplacental unit is associated with increased resistance to blood flow in the fetal-placental circulation. These changes can lead to adverse cardiovascular events in adulthood. This study investigates whether L-arginine (substrate for nitric oxide synthase (NOS) or endothelin-A receptor antagonist BQ123 administration reverses hypoxia-induced changes in perfusion pressure in the fetal compartment in dual-perfused placental cotyledons. METHODS: Human placental cotyledons (n = 15) from term deliveries (n = 15) were perfused with Krebs solution from maternal and fetal sides. Normal and reduced oxygen tension conditions were sequentially created in the perfused maternal compartment. Fetal perfusion pressure was continuously monitored. 1 mM L-arginine, D-arginine (an enantiomer of L-arginine and not a substrate for NOS), and BQ123 or normal saline were administered to the fetal compartment; L-arginine was also administered to the maternal compartment prior to maternal side hypoxia. Changes in perfusion pressure were compared between groups. RESULTS: Maternal hypoxia increased (19 ± 6%) perfusion pressure and this was blunted by L-arginine injection (3 ± 5%; p = 0.006) into the fetal compartment. L-arginine in the maternal compartment had no significant effect (22 ± 4% with L-arginine vs.14 ± 3% at control) on perfusion pressure. Similarly, D-arginine (23 ± 11% vs.19 ± 8% at control) or BQ123 (12 ± 3% vs.13 ± 3% at control) in the fetal compartment did not blunt the hypoxia-induced increase in perfusion pressure. CONCLUSIONS: Fetal vasoconstriction induced by maternal hypoxia is blunted by NO synthase substrate L-arginine, but not by D-arginine, in the fetal compartment, suggesting the involvement of NO synthesis in regulating the hypoxia-induced fetal vasoconstriction. Endothelin A receptor-related mechanisms does not appear to play a role in the maternal hypoxia-induced fetal vasoconstriction.

In vitro myometrial contractility profiles of different pharmacological agents used for induction of labor.

OBJECTIVE: To investigate the effects of different pharmacological induction agents on myometrial contractility. STUDY DESIGN: Myometrial biopsies were obtained from 13 term nonlaboring women undergoing scheduled cesarean delivery. Tissue strips were suspended in organ chambers for isometric tension recording. The effects of cumulative doses (10-10 mol/L to 10-5 mol/L) of prostaglandin E1 (PGE1), E2 (PGE2), and oxytocin on spontaneous uterine contractility were determined. Areas under the contraction curve were compared using one-way analysis of variance on ranks with Dunn post hoc test. RESULTS: Oxytocin-induced myometrial contractility was superior to PGE1, PGE2, and time controls (CTR) at all the concentrations tested. When only prostaglandins were compared with CTR, PGE1 10-5 mol/L increased myometrial contractility, and PGE2 had no effects. CONCLUSION: Oxytocin and prostaglandins have different effects on myometrial contractility accounting for different mechanisms of action and side effects. The increased uterine contractility observed with PGE1 as compared with PGE2 can contribute to explain the higher success of vaginal delivery.

Endothelial growth factor therapy improves preeclampsia-like manifestations in a murine model induced by overexpression of sVEGFR-1.

This study examines the effects of VEGF-121 therapy in an animal model of preeclampsia induced by overexpression of soluble VEGF receptor 1 (sVEGFR-1). At day 8 of gestation, CD-1 mice were implanted with subcutaneous osmotic pumps containing either VEGF-121 or vehicle and fitted with telemetric blood pressure (BP) catheters for continuous BP monitoring (days 8-18 of gestation). On day 9, the animals in the VEGF-121 group were randomly allocated for injection with adenovirus carrying sVEGFR-1 or the murine immunoglobulin G2α Fc fragment (mFc) as virus control (Adv-sVEGFR-1; Adv-mFc). Animals in the vehicle group were injected with Adv-sVEGFR-1. On day 18, mice were euthanized, placentas and pups weighted, carotid arteries isolated, and their responses studied in vitro using a wire myograph for isometric tension recording. In mice overexpressing sVEGFR-1, treatment with VEGF-121 significantly reduced BP from days 10 to 18 of gestation compared with that of vehicle. VEGF-sVEGFR-1 animals had significantly higher vasorelaxant response to sodium nitroprusside and significantly lower contractile response to the thromboxane agonist (U-46619) compared with that of the vehicle-sVEGFR-1 mice. Phenylephrine and acetylcholine responses did not significantly vary between the VEGF-sVEGFR-1 and the vehicle-sVEGFR-1 mice. Average pup weight was significantly lower in the vehicle-sVEGFR-1 group compared with the VEGF-sVEGFR-1 and VEGF-mFc groups. In conclusion, VEGF-121 therapy attenuates vascular dysfunction and diminishes intrauterine growth abnormality in an animal model of preeclampsia induced by overexpression of sVEGFR-1. Modulation of VEGF pathway turns into a promising therapeutic approach of preeclampsia.

Effect of maternal body mass index on in vitro response to tocolytics in term myometrium.

OBJECTIVE: We sought to investigate the effect of body mass index (BMI) on in vitro response to tocolytics. STUDY DESIGN: Myometrial biopsies were obtained at the time of scheduled cesarean deliveries from term nonlaboring women with BMI < or =29.9 (26.3 +/- 1.3; n = 7), 30-34.9 (31.8 +/- 1.2; n = 16), and > or = 35 (39.5 +/- 4.9; n = 9). Tissue strips were suspended in organ chambers for isometric tension recording. The effects of cumulative doses (10(-10) to 10(-5) mol/L) of nifedipine or indomethacin on spontaneous uterine contractility were determined. Areas under the contraction curve were compared using 1-way analysis of variance with Tukey post hoc test. RESULTS: Myometrial response to tocolytics did not differ between the BMI groups. Nifedipine, but not indomethacin, significantly inhibited myometrial contractility independent of BMI. CONCLUSION: BMI does not affect uterine response to tocolytics in isolated uterine tissue from term nonlaboring women.

Does sildenafil citrate affect myometrial contractile response to nifedipine in vitro?

OBJECTIVE: We sought to test the hypothesis that sildenafil citrate (SC) at low concentrations potentiates the tocolytic effects of nifedipine in vitro. STUDY DESIGN: Myometrial biopsies were obtained from 22 term nonlaboring women undergoing scheduled cesarean delivery. Tissue strips were suspended in organ chambers for isometric tension recording, and incubated for 30 minutes with either SC at 231 ng/mL or solvent. The effects of cumulative doses (10(-10) to 10(-5) mol/L) of nifedipine on spontaneous and oxytocin-induced uterine contractility were then determined. Areas under the contraction curve were compared using 1-way analysis of variance with Tukey post hoc test (significance: P < .05). RESULTS: Nifedipine significantly inhibited spontaneous and oxytocin-induced myometrial contractility. Preincubation with SC increased response to nifedipine and significantly potentiated its inhibitory effect at 10(-8) mol/L, without affecting oxytocin-induced contractile response. CONCLUSION: At concentrations within a therapeutic window, SC increases myometrial sensitivity to nifedipine.

The effect of prepregnancy obesity and sFlt-1-induced preeclampsia-like syndrome on fetal programming of adult vascular function in a mouse model.

OBJECTIVE: The purpose of this study was to test the hypothesis that prepregnancy obesity and soluble fms-like tyrosine kinase-1 (sFlt-1)-induced preeclampsia lead to altered vascular function in the offspring later in life. STUDY DESIGN: CD-1 female mice were placed on a low-fat (LF) or high-fat (HF) diet before mating. On day 8 of pregnancy, the HF mice were injected with adenovirus that carried either sFlt-1 (HF sFlt-1) or murine immunoglobulin G2alpha Fc fragment (HF mFc). LF dams received saline solution. After being weaned, all offspring were placed on a standard diet. At 3 months of age, the carotid artery was isolated for in vitro vascular reactivity studies. RESULTS: Among male offspring, the response to phenylephrine was significantly lower in the HF sFlt-1 group. The response to serotonin in males and to thromboxane in females was lower in the HF sFlt-1 and HF mFc groups. In females, the HF sFlt-1 and LF groups displayed less relaxation to acetylcholine. The response to phenylephrine was significantly lower in females than males in the HF mFc and LF groups. The response to thromboxane was significantly lower in the HF sFlt-1 females, compared with males. CONCLUSION: Prepregnancy obesity and preeclampsia alter fetal programming of adult vascular function. The mechanism is complex and gender specific.

Characterization of a murine model of fetal programming of atherosclerosis.

OBJECTIVE: The objective of the study was to investigate the effect of fetal programming on the development of atherosclerosis in the offspring in a mouse model. STUDY DESIGN: Male and female mice of the wild type and the knockout for the apoprotein E (apoE) gene were cross-bred to obtain all 4 possible genetic offspring types. The offspring were kept on regular chow and killed at 8 months of age. Levels of total cholesterol and triglycerides were determined. The aortic arch was examined for the presence and severity of atherosclerosis. Kidney and liver sections were analyzed for pathologic changes. RESULTS: We found increased total cholesterol levels and incidence of atherosclerosis in offspring born to hypercholesterolemic mothers as compared with genomically similar animals born to wild-type mothers. These animals also showed kidney and liver lesions consistent with chronic hypercholesterolemia. CONCLUSIONS: There is a strong effect of fetal programming on the development of atherosclerosis in the apoE mouse model.