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Dexamethasone is frequently prescribed for preterm infants to wean from respiratory support and/or to facilitate extubation. This pre-/postintervention prospective study ascertained the impact on clinical (respiratory support) and echocardiographic parameters after dexamethasone therapy in preterm fetal growth restriction (FGR) infants compared with appropriate for gestational age (AGA) infants. Echocardiography was performed within 24 h before the start and after completion of 10-day therapy. Parameters assessed included those reflecting pulmonary vascular resistance and right ventricular output. Seventeen FGR infants (birth gestation and birth weight, 25.2 ± 1.1 wk and 497 ± 92 g, respectively) were compared with 22 AGA infants (gestation and birth weight, 24.5 ± 0.8 and 663 ± 100 g, respectively). Baseline respiratory severity score (mean airway pressure × fractional inspired oxygen) was comparable between the groups, (median [interquartile range] FGR, 10 [6, 13] vs. AGA, 8 ± 2.8, P = 0.08). Pre-dexamethasone parameters of pulmonary vascular resistance (FGR, 0.19 ± 0.03 vs. AGA, 0.2 ± 0.03, P = 0.16) and right ventricular output (FGR, 171 ± 20 vs. 174 ± 17 mL/kg/min, P = 0.6) were statistically comparable. At post-dexamethasone assessments, the decrease in the respiratory severity score was significantly greater in AGA infants (median [interquartile range] FGR, 10 [6, 13] to 9 [2.6, 13.5], P = 0.009 vs. AGA, 8 ± 2.8 to 3 ± 1, P < 0.0001). Improvement in measures of pulmonary vascular resistance (ratio of time to peak velocity to right ventricular ejection time) was greater in AGA infants (FGR, 0.19 ± 0.03 to 0.2 ± 0.03, P = 0.13 vs. AGA 0.2 ± 0.03 to 0.25 ± 0.03, P < 0.0001). The improvement in right ventricular output was significantly greater in AGA infants (171 ± 20 to 190 ± 21, P = 0.014 vs. 174 ± 17 to 203 ± 22, P < 0.0001). This highlights differential cardiorespiratory responsiveness to dexamethasone in extremely preterm FGR infants, which may reflect the in utero maladaptive state. NEW & NOTEWORTHY Dexamethasone (DEX) is frequently used in preterm infants dependent on ventilator support. Differences in vascular structure and function that may have developed prenatally arising from the chronic intrauterine hypoxemia in FGR infants may adversely affect responsiveness. The clinical efficacy of DEX was significantly less in FGR (birth weight < 10th centile) infants, compared with appropriate for gestational age (AGA) infants. Echocardiography showed significantly less improvement in pulmonary vascular resistance in FGR, compared with AGA infants.

One of the initiating events in preeclampsia (PE) is placental ischemia. Rodent models of placental ischemia do not present with vascular endothelial dysfunction, a hallmark of PE. We previously demonstrated a role for leptin in endothelial dysfunction in pregnancy in the absence of placental ischemia. We hypothesized that placental ischemia requires hyperleptinemia and endothelial mineralocorticoid receptor (ECMR) expression to induce PE-associated endothelial dysfunction in pregnant mice. We induced placental ischemia via the reduced uterine perfusion pressure (RUPP) procedure in pregnant ECMR-intact ( ECMR +/+ ) and ECMR deletion ( ECMR -/- ) mice at gestational day (GD) 13 . ECMR +/+ RUPP pregnant mice also received concurrent leptin infusion via miniosmotic pump (0.9 mg/kg/day). RUPP increased blood pressure via radiotelemetry and decreased fetal growth in ECMR +/+ pregnant mice. Both increases in blood pressure and reduced fetal growth were abolished in RUPP ECMR -/- mice. Placental ischemia did not decrease endothelial-dependent relaxation to acetylcholine (ACh) but increased phenylephrine (Phe) contraction in mesenteric arteries of pregnant mice, which was ablated by ECMR deletion. Addition of leptin to RUPP mice significantly reduced ACh relaxation in ECMR +/+ pregnant mice, accompanied by an increase in soluble FMS-like tyrosine kinase-1 (sFlt-1)/placental growth factor (PLGF) ratio. In conclusion, our data indicate that high leptin levels drive endothelial dysfunction in PE and that ECMR is required for clinical characteristics of hypertension and fetal growth restriction in placental ischemia PE. Collectively, we show that both ECMR and leptin play a role to mediate PE. NEW & NOTEWORTHY Leptin is a key feature of preeclampsia that initiates vascular endothelial dysfunction in preeclampsia characterized by placental ischemia. Endothelial mineralocorticoid receptor (ECMR) deletion in placental ischemia protects pregnant mice from elevations in blood pressure and fetal growth restriction in pregnancy. Increases in leptin production mediate the key pathological feature of endothelial dysfunction in preeclampsia in rodents. ECMR activation contributes to the increase in blood pressure and fetal growth restriction in preeclampsia.

The reduced uterine perfusion pressure (RUPP) model is frequently used to study preeclampsia and fetal growth restriction. An improved understanding of influential factors might improve reproducibility and reduce animal use considering the variability in RUPP phenotype. We performed a systematic review and meta-analysis by searching Medline and Embase (until 28 March, 2023) for RUPP studies in murine. Primary outcomes included maternal blood pressure (BP) or proteinuria, fetal weight or crown-rump length, fetal reabsorptions, or antiangiogenic factors. We aimed to identify influential factors by meta-regression analysis. We included 155 studies. Our meta-analysis showed that the RUPP procedure results in significantly higher BP (MD = 24.1 mmHg; [22.6; 25.7]; n = 148), proteinuria (SMD = 2.3; [0.9; 3.8]; n = 28), fetal reabsorptions (MD = 50.4%; [45.5; 55.2]; n = 42), circulating soluble FMS-like tyrosine kinase-1 (sFlt-1) (SMD = 2.6; [1.7; 3.4]; n = 34), and lower fetal weight (MD = -0.4 g; [-0.47; -0.34]; n = 113. The heterogeneity (variability between studies) in primary outcomes appeared ≥90%. Our meta-regression identified influential factors in the method and time point of BP measurement, randomization in fetal weight, and type of control group in sFlt-1. The RUPP is a robust model considering the evident differences in maternal and fetal outcomes. The high heterogeneity reflects the observed variability in phenotype. Because of underreporting, we observed reporting bias and a high risk of bias. We recommend standardizing study design by optimal time point and method chosen for readout measures to limit the variability. This contributes to improved reproducibility and thereby eventually improves the translational value of the RUPP model.

High-altitude (HA) hypoxia lowers uterine artery (UtA) blood flow during pregnancy and birth weight. Adenosine monophosphate kinase (AMPK) activation has selective, uteroplacental vasodilator effects that lessen hypoxia-associated birth weight reductions. In this study, we determined the relationship between AMPK-pathway gene expression and metabolites in the maternal circulation during HA pregnancy as well as with the maintenance of UtA blood flow and birth weight at HA. Residents at HA (2,793 m) versus low altitude (LA; 1,640 m) had smaller UtA diameters at weeks 20 and 34 , lower UtA blood flow at week 20 , and lower birth weight babies. At week 34 , women residing at HA versus women residing at LA had decreased expression of upstream and downstream AMPK-pathway genes. Expression of the α 1 -AMPK catalytic subunit, PRKAA1 , correlated positively with UtA diameter and blood flow at weeks 20 (HA) and 34 (LA). Downstream AMPK-pathway gene expression positively correlated with week 20 fetal biometry at both altitudes and with UtA diameter and birth weight at LA. Reduced gene expression of AMPK activators and downstream targets in women residing at HA versus women residing at LA, together with positive correlations between PRKAA1 gene expression, UtA diameter, and blood flow suggest that greater sensitivity to AMPK activation at midgestation at HA may help offset later depressant effects of hypoxia on fetal growth. NEW & NOTEWORTHY Fetal growth restriction (FGR) is increased and uterine artery (UtA) blood flow is lower at high altitudes (HA) but not all HA pregnancies have FGR. Here we show that greater UtA diameter and blood flow at week 20 are positively correlated with higher expression of the gene encoding the α 1 -catalytic subunit of AMP protein kinase, PRKAA1 , suggesting that increased AMPK activation may help to prevent the detrimental effects of chronic hypoxia on fetal growth.

Intrauterine growth restriction (IUGR) is a common complication of pregnancy. We previously demonstrated that IUGR is associated with an impaired nitric oxide (NO)-induced relaxation in the human umbilical vein (HUV) of growth-restricted females compared to appropriate for gestational age (AGA) newborns. We found that phosphodiesterase (PDE) inhibition improved NO-induced relaxation in HUV, suggesting that PDEs could represent promising targets for therapeutic intervention. This study aimed to investigate the effects of PDE inhibition on human umbilical arteries (HUAs) compared to HUV. Umbilical vessels were collected in IUGR and AGA term newborns. NO-induced relaxation was studied using isolated vessel tension experiments in the presence or absence of the nonspecific PDE inhibitor 3-isobutyl-1-methylxanthine (IBMX). PDE1B, PDE1C, PDE3A, PDE4B, and PDE5A were investigated by Western blot. NO-induced vasodilation was similar between IUGR and AGA HUAs. In HUAs precontracted with serotonin, IBMX enhanced NO-induced relaxation only in IUGR females, whereas in HUV IBMX increased NO-induced relaxation in all groups except IUGR males. In umbilical vessels preconstricted with the thromboxane A2 analog U46619, IBMX improved NO-induced relaxation in all groups to a greater extent in HUV than HUAs. However, the PDE protein content was higher in HUAs than HUV in all study groups. Therefore, the effects of PDE inhibition depend on the presence of IUGR, fetal sex, vessel type, and vasoconstrictors implicated. Despite a higher PDE protein content, HUAs are less sensitive to IBMX than HUV, which could lead to adverse effects of PDE inhibition in vivo by impairment of the fetoplacental hemodynamics. NEW & NOTEWORTHY The effects of phosphodiesterase inhibition on the umbilical circulation depend on the presence of intrauterine growth restriction, the fetal sex, vessel type, and vasoconstrictors implicated. The human umbilical vascular tone regulation is complex and depends on the amount and activity of specific proteins but also probably on the subcellular organization mediating protein interactions. Therefore, therapeutic interventions using phosphodiesterase inhibitors to improve the placental-fetal circulation should consider fetal sex and both umbilical vein and artery reactivity.

Fetal growth restriction (FGR) increases cardiovascular risk by cardiac remodeling and programming. This systematic review and meta-analysis across species examines the use of echocardiography in FGR offspring at different ages. PubMed and Embase.com were searched for animal and human studies reporting on echocardiographic parameters in placental insufficiency-induced FGR offspring. We included six animal and 49 human studies. Although unable to perform a meta-analysis of animal studies because of insufficient number of studies per individual outcome, all studies showed left ventricular dysfunction. Our meta-analyses of human studies revealed a reduced left ventricular mass, interventricular septum thickness, mitral annular peak velocity, and mitral lateral early diastolic velocity at neonatal age. No echocardiographic differences during childhood were observed, although the small age range and number of studies limited these analyses. Only two studies at adult age were performed. Meta-regression on other influential factors was not possible due to underreporting. The few studies on myocardial strain analysis showed small changes in global longitudinal strain in FGR offspring. The quality of the human studies was considered low and the risk of bias in animal studies was mostly unclear. Echocardiography may offer a noninvasive tool to detect early signs of cardiovascular predisposition following FGR. Clinical implementation yet faces multiple challenges including identification of the most optimal timing and the exact relation to long-term cardiovascular function in which echocardiography alone might be limited to reflect a child's vascular status. Future research should focus on myocardial strain analysis and the combination of other (non)imaging techniques for an improved risk estimation. NEW & NOTEWORTHY Our meta-analysis revealed echocardiographic differences between fetal growth-restricted and control offspring in humans during the neonatal period: a reduced left ventricular mass and interventricular septum thickness, reduced mitral annular peak velocity, and mitral lateral early diastolic velocity. We were unable to pool echocardiographic parameters in animal studies and human adults because of an insufficient number of studies per individual outcome. The few studies on myocardial strain analysis showed small preclinical changes in FGR offspring.

Angiotensin-converting enzyme 2 (ACE2) is a membrane-bound protein containing 805 amino acids. ACE2 shows approximately 42% sequence similarity to somatic ACE but has different biochemical activities. The key role of ACE2 is to catalyze the vasoconstrictor peptide angiotensin (ANG) II to Ang-(1-7), thus regulating the two major counterbalancing pathways of the renin-angiotensin system (RAS). In this way, ACE2 plays a protective role in end-organ damage by protecting tissues from the proinflammatory actions of ANG II. The circulating RAS is activated in normal pregnancy and is essential for maintaining fluid and electrolyte homeostasis and blood pressure. Renin-angiotensin systems are also found in the conceptus. In this review, we summarize the current knowledge on the regulation and function of circulating and uteroplacental ACE2 in uncomplicated and complicated pregnancies, including those affected by preeclampsia and fetal growth restriction. Since ACE2 is the receptor for SARS-CoV-2, and COVID-19 in pregnancy is associated with more severe disease and increased risk of abnormal pregnancy outcomes, we also discuss the role of ACE2 in mediating some of these adverse consequences. We propose that dysregulation of ACE2 plays a critical role in the development of preeclampsia, fetal growth restriction, and COVID-19-associated pregnancy pathologies and suggest that human recombinant soluble ACE2 could be a novel therapeutic to treat and/or prevent these pregnancy complications.

Preeclampsia (PE) is characterized by maternal hypertension, intrauterine growth restriction, and increased cytolytic natural killer cells (cNKs), which secrete interferon γ (IFNγ). However, the precise role of IFNγ in contributing to PE pathophysiology remains unclear. Using the reduced uterine perfusion pressure (RUPP) rat model of placental ischemia, we tested the hypothesis that neutralization of IFNγ in RUPPs will decrease placental reactive oxygen species (ROS) and improve vascular function resulting in decreased MAP and improved fetal growth. On gestation day ( GD ) 14 , the RUPP procedure was performed and on GDs 15 and 18 , a subset of normal pregnant rats (NP) and RUPP rats were injected with 10 μg/kg of an anti-rat IFNγ monoclonal antibody. On GD 18 , uterine artery resistance index (UARI) was measured via Doppler ultrasound and on GD 19 , mean arterial pressure (MAP) was measured, animals were euthanized, and blood and tissues were collected for analysis. Increased MAP was observed in RUPP rats compared with NP and was reduced in RUPP + anti-IFNγ. Placental ROS was also increased in RUPP rats compared with NP rats and was normalized in RUPP + anti-IFNγ. Fetal and placental weights were reduced in RUPP rats, but were not improved following anti-IFNγ treatment. However, UARI was elevated in RUPP compared with NP rats and was reduced in RUPP + anti-IFNγ. In conclusion, we observed that IFNγ neutralization reduced MAP, UARI, and placental ROS in RUPP recipients. These data suggest that IFNγ is a potential mechanism by which cNKs contribute to PE pathophysiology and may represent a therapeutic target to improve maternal outcomes in PE.

Intrauterine growth restriction (IUGR) due to an adverse intrauterine environment predisposes to arterial hypertension and loss of kidney function. Here, we investigated whether vascular dysregulation in renal interlobar arteries (RIAs) may contribute to hypertensive glomerular damage after IUGR. In rats, IUGR was induced by bilateral uterine vessel ligation. Offspring of nonoperated rats served as controls. From postnatal day 49 , blood pressure was telemetrically recorded. On postnatal day 70 , we evaluated contractile function in RIAs and mesenteric arteries. In addition, blood, urine, and glomerular parameters as well as renal collagen deposition were analyzed. IUGR RIAs not only showed loss of stretch activation in 9 of 11 arteries and reduced stretch-induced myogenic tone but also showed a shift of the concentration-response relation of acetylcholine-induced relaxation toward lower concentrations. However, IUGR RIAs also exhibited augmented contractions through phenylephrine. Systemic mean arterial pressure [mean difference: 4.8 mmHg (daytime) and 5.7 mmHg (night)], mean glomerular area (IUGR: 9,754 ± 338 µm 2 and control: 8,395 ± 227 µm 2 ), and urinary protein-to-creatinine ratio (IUGR: 1.67 ± 0.13 g/g and control: 1.26 ± 0.10 g/g) were elevated after IUGR. We conclude that male IUGR rat offspring may have increased vulnerability toward hypertensive glomerular damage due to loss of myogenic tone and augmented endothelium-dependent relaxation in RIAs. NEW & NOTEWORTHY For the first time, our study presents wire myography data from renal interlobar arteries (RIAs) and mesenteric arteries of young adult rat offspring after intrauterine growth restriction (IUGR). Our data indicate that myogenic tone in RIAs is dysfunctional after IUGR. Furthermore, IUGR offspring suffer from mild arterial hypertension, glomerular hypertrophy, and increased urinary protein-to-creatinine ratio. Dysregulation of vascular tone in RIAs could be an important variable that impacts upon vulnerability toward glomerular injury after IUGR.

Preeclampsia (PE) is characterized by new-onset hypertension in association with elevated natural killer (NK) cells and inflammatory cytokines, which are likely culprits for decreased fetal weight during PE pregnancies. As progesterone increases during normal pregnancy, it stimulates progesterone-induced blocking factor (PIBF). PIBF has been shown to decrease inflammation and cytolytic NK cells, both of which are increased during PE. We hypothesized that PIBF reduces inflammation as a mechanism to improve hypertension in the preclinical reduced uterine perfusion pressure (RUPP) rat model of PE. PIBF (2.0 µg/mL) was administered intraperitoneally on gestational day 15 to either RUPP or normal pregnant (NP) rats. On day 18 , carotid catheters were inserted. Mean arterial blood pressure (MAP) and samples were collected on day 19 . MAP in NP rats ( n = 11) was 100 ± 2 mmHg and 105 ± 3 mmHg in NP + PIBF rats ( n = 8) and 122 ± 1 mmHg in RUPP rats ( n = 10), which improved to 110 ± 2 mmHg in RUPP + PIBF rats ( n = 11), P < 0.05. Pup weight was 2.4 ± 0.1 g in NP, 2.5 ± 0.1 g in NP + PIBF, 1.9 ± 0.1 g in RUPP, and improved to 2.1 ± 0.1 g in RUPP + PIBF rats. Circulating and placental cytolytic NK cells, IL-17, and IL-6 were significantly reduced while IL-4 and T helper (TH) 2 cells were significantly increased in RUPP rats after PIBF administration. Importantly, vasoactive pathways preproendothelin-1, nitric oxide, and soluble fms-Like tyrosine Kinase-1 (sFlt-1) were normalized in RUPP + PIBF rats compared with RUPP rats, P < 0.05. Our findings suggest that PIBF normalized IL-4/TH2 cells, which was associated with improved inflammation, fetal growth restriction, and blood pressure in the RUPP rat model of PE.

Currently, there is no effective treatment for placental dysfunction in utero. In a ligated mouse model of fetal growth restriction (FGR), nanoparticle-mediated human insulin-like 1 growth factor ( hIGF1 ) gene delivery (NP-Plac1-hIGF1) increased hIGF1 expression and maintained fetal growth. However, whether it can restore fetal growth remains to be determined. Using the endothelial nitric oxide synthase knockout (eNOS -/- ) mouse model, a genetic model of FGR, we found that despite inducing expression of hIGF1 in the placentas treated with NP-Plac1-hIGF1 ( P = 0.0425), FGR did not resolve. This was associated with no change to the number of fetal capillaries in the placental labyrinth; an outcome which was increased with NP-Plac1-hIGF1 treatment in the ligated mouse model, despite increased expression of angiopoietin 1 ( P = 0.05), and suggested IGF1 signaling in the placenta requires eNOS to modulate placenta angiogenesis. To further assess this hypothesis, BeWo choriocarcinoma cell line and human placental explant cultures were treated with NP-Plac1-hIGF1, oxidative stress was induced with hydrogen peroxide (H 2 O 2 ), and NOS activity was inhibited using the inhibitor N G -monomethyl-l-arginine (l-NMMA). In both BeWo cells and explants, the protective effect of NP-Plac1-hIGF1 treatment against H 2 O 2 -induced cell death/lactate dehydrogenase release was prevented by eNOS inhibition ( P = 0.003 and P < 0.0001, respectively). This was associated with an increase in mRNA expression of oxidative stress markers hypoxia inducing factor 1α ( HIF1α ; P < 0.0001) and ADAM10 ( P = 0.0002) in the NP-Plac1-hIGF1 + H 2 O 2 + l-NMMA-treated BeWo cells. These findings show for the first time the requirement of eNOS/NOS in IGF1 signaling in placenta cells that may have implications for placental angiogenesis and fetal growth.

Intrauterine growth restriction programs adult cardiorenal disease, which may be exacerbated by pregnancy and obesity. Importantly, exercise has positive cardiovascular effects. This study determined if high-fat feeding exacerbates the known adverse cardiorenal adaptations to pregnancy in rats born small and whether endurance exercise can prevent these complications. Uteroplacental insufficiency was induced by bilateral uterine vessel ligation (Restricted) or sham (Control) surgery on embryonic day 18 (E18) in Wistar-Kyoto rats. Female offspring consumed a Chow or high-fat diet (HFD) from weaning and were randomly allocated to either a sedentary (Sedentary) or an exercise protocol at 16 wk; exercised before and during pregnancy (Exercise), or exercised during pregnancy only (PregEx). Systolic blood pressure was measured prepregnancy and rats were mated at 20 wk. During pregnancy, systolic blood pressure (E18) and renal function (E19) were assessed. Sedentary HFD Control females had increased estimated glomerular filtration rate (eGFR) compared with Chow. Compared with Control, Sedentary-Restricted females had increased eGFR, which was not influenced by HFD. Renal function was not affected by exercise and prepregnancy blood pressure was not altered. Restricted Chow-fed dams and dams fed a high-fat diet had a greater reduction in systolic blood pressure during late gestation, which was only prevented by Exercise. In summary, high-fat fed females born small are at a greater risk of altered cardiorenal adaptations to pregnancy. Although cardiovascular dysfunction was prevented by Exercise, renal dysfunction was not affected by exercise interventions. This study highlights that modifiable risk factors can have beneficial effects in the mother during pregnancy, which may impact fetal growth and development.

We hypothesized that the physiological adaptations of the fetus in response to chronic intrauterine hypoxia depend on its sex and the gestational age of exposure. Pregnant guinea pigs were exposed to room air (normoxia, NMX) or 10.5% O 2 (hypoxia, HPX) at either 25 days (early onset) or 50 days (late onset) of gestation until term (~65 days). We evaluated the effects of HPX on hemodynamic and cardiac function indices using Doppler ultrasound and determined sex-related differences in near-term fetuses. Indices of uterine/umbilical artery pulsatility (PI index) and fetal heart systolic and diastolic function [Tei index and passive filling (E-wave) to filling due to atrial contraction (A-wave) (E/A ratios), respectively] were measured in utero and fetal body (FBW) and organ weights measured from extracted fetuses. Both early- and late-onset HPX decreased FBW in both males and females, had no effect on placenta weights, and increased placenta weight-to-FBW ratios. Early- but not late-onset HPX increased uterine artery PI, but neither HPX condition affected umbilical artery PI. Early-onset HPX increased left ventricle E/A ratios in both males and females, whereas late-onset HPX increased the right ventricle E/A ratio in females only. Hypoxia had no effect on the Tei index in either sex. Early- and late-onset HPX induce placental insufficiency and fetal growth restriction and increase diastolic filling depending on the sex, with female fetuses having a greater capacity than males to compensate for intrauterine hypoxia.

High-altitude (>2,500 m) residence increases the incidence of intrauterine growth restriction (IUGR) due, in part, to reduced uterine artery blood flow and impaired myometrial artery (MA) vasodilator response. A role for the AMP-activated protein kinase (AMPK) pathway in protecting against hypoxia-associated IUGR is suggested by genomic and transcriptomic studies in humans and functional studies in mice. AMPK is a hypoxia-sensitive metabolic sensor with vasodilatory properties. Here we hypothesized that AMPK-dependent vasodilation was increased in MAs from high versus low-altitude (<1,700 m) Colorado women with appropriate for gestational age (AGA) pregnancies and reduced in IUGR pregnancies regardless of altitude. Vasoreactivity studies showed that, in AGA pregnancies, MAs from high-altitude women were more sensitive to vasodilation by activation of AMPK with A769662 due chiefly to increased endothelial nitric oxide production, whereas MA responses to AMPK activation in the low-altitude women were endothelium independent. MAs from IUGR compared with AGA pregnancies had blunted vasodilator responses to acetylcholine at high altitude. We concluded that 1 ) blunted vasodilator responses in IUGR pregnancies confirm the importance of MA vasodilation for normal fetal growth and 2 ) the increased sensitivity to AMPK activation in AGA pregnancies at high altitude suggests that AMPK activation helped maintain MA vasodilation and fetal growth. These results highlight a novel mechanism for vasodilation of MAs under conditions of chronic hypoxia and suggest that AMPK activation could provide a therapy for increasing uteroplacental blood flow and improving fetal growth in IUGR pregnancies. NEW & NOTEWORTHY Intrauterine growth restriction (IUGR) impairs infant well- being and increases susceptibility to later-in-life diseases for mother and child. Our study reveals a novel role for AMPK in vasodilating the myometrial artery (MA) from women residing at high altitude (>2,500 m) with appropriate for gestational age pregnancies but not in IUGR pregnancies at any altitude.

Women in low- and middle-income countries frequently consume a protein-deficient diet during pregnancy and breastfeeding. The effects of gestational malnutrition on fetal and early postnatal development can have lasting adverse effects on offspring metabolism. Expanding on previous studies in rodent models, we utilized a nonhuman primate model of gestational and early-life protein restriction (PR) to evaluate effects on the organ development and glucose metabolism of juvenile offspring. Offspring were born to dams that had consumed a control diet containing 26% protein or a PR diet containing 13% protein. Offspring were maintained on the PR diet and studied [body and serum measurements, intravenous glucose tolerance tests (ivGTTs), and dual-energy X-ray absorptiometry scans] up to 7 mo of age, at which time tissues were collected for analysis. PR offspring had age-appropriate body weight and were euglycemic but exhibited elevated fasting insulin and reduced initial, but increased total, insulin secretion during an ivGTT at 6 mo of age. No changes were detected in pancreatic islets of PR juveniles; however, PR did induce changes, including reduced kidney size, and changes in liver, adipose tissue, and muscle gene expression in other peripheral organs. Serum osteocalcin was elevated and bone mineral content and density were reduced in PR juveniles, indicating a significant impact of PR on early postnatal bone development.

Preeclampsia is a prevalent pregnancy complication characterized by new-onset maternal hypertension and inflammation, with placental ischemia as the initiating event. Studies of others have provided evidence for the importance of lymphocytes in placental ischemia-induced hypertension; however, the contributions of B1 versus B2 lymphocytes are unknown. We hypothesized that peritoneal B1 lymphocytes are important for placental ischemia-induced hypertension. As an initial test of this hypothesis, the effect of anti-CD20 depletion on both B-cell populations was determined in a reduced utero-placental perfusion pressure (RUPP) model of preeclampsia. Anti-murine CD20 monoclonal antibody (5 mg/kg, Clone 5D2) or corresponding mu IgG2a isotype control was administered intraperitoneally to timed pregnant Sprague-Dawley rats on gestation day (GD)10 and 13. RUPP or sham control surgeries were performed on GD14, and mean arterial pressure (MAP) was measured on GD19 from a carotid catheter. As anticipated, RUPP surgery increased MAP and heart rate and decreased mean fetal and placental weight. However, anti-CD20 treatment did not affect these responses. On GD19, B-cell populations were enumerated in the blood, peritoneal cavity, spleen, and placenta with flow cytometry. B1 and B2 cells were not significantly increased following RUPP. Anti-CD20 depleted B1 and B2 cells in peritoneum and circulation but depleted only B2 lymphocytes in spleen and placenta, with no effect on circulating or peritoneal IgM. Overall, these data do not exclude a role for antibodies produced by B cells before depletion but indicate the presence of B lymphocytes in the last trimester of pregnancy is not critical for placental ischemia-induced hypertension. NEW & NOTEWORTHY The adaptive and innate immune systems are implicated in hypertension, including the pregnancy-specific hypertensive condition preeclampsia. However, the mechanism of immune system dysfunction leading to pregnancy-induced hypertension is unresolved. In contrast to previous reports, this study reveals that the presence of classic B2 lymphocytes and peritoneal and circulating B1 lymphocytes is not required for development of hypertension following third trimester placental ischemia in a rat model of pregnancy-induced hypertension.

Background: Fetal growth restriction (FGR) is a major risk factor for bronchopulmonary dysplasia (BPD). Maternal stress and poor diet are linked to FGR. Effect of perinatal stress on lung development remains unknown., Objective: Using a murine model of adverse early life environment (AELE), we hypothesized that maternal exposure to perinatal environmental stress and high-fat diet (Western diet) lead to impaired lung development in the offspring., Methods: Female mice were placed on either control diet or Western diet before conception. Those exposed to Western diet were also exposed to perinatal environmental stress, the combination referred to as AELE. Pups were either euthanized at postnatal day 21 (P21) or weaned to control diet and environment until adulthood (8-14 wk old). Lungs were harvested for histology, gene expression by quantitative RT-PCR, microRNA profiling, and immunoblotting., Results: AELE increased the mean linear intercept and decreased the radial alveolar count and secondary septation in P21 and adult mice. Capillary count was also decreased in P21 and adult mice. AELE lungs had decreased vascular endothelial growth factor A (VEGFA), VEGF receptor 2, endothelial nitric oxide synthase, and hypoxia inducible factor-1α protein levels and increased expression of genes that regulate DNA methylation and upregulation of microRNAs that target genes involved in lung development at P21., Conclusion: AELE leads to impaired lung alveolar and vascular growth, which persists into adult age despite normalizing the diet and environment at P21. AELE also alters the expression of genes involved in lung remodeling.

Intrauterine growth restriction (IUGR) and maternal high-fat diet (HFD) independently predispose offspring to hypertension. In a rat model, IUGR more so than maternal HFD increases arterial stiffness with vascular remodeling as early as postnatal day (PND) 21 . The trajectory of such early vascular changes remains unknown. We hypothesized that IUGR would increase blood pressure (BP), arterial stiffness, and markers of ongoing detrimental vascular remodeling in adult rats exposed to a maternal HFD regardless of weaning diet. Adult female rats were fed either a regular diet (RD) or an HFD before mating through lactation. IUGR was induced by uterine artery ligation. Offspring were weaned to either a RD or HFD through PND 60. For both control and IUGR rats, this design resulted in the following three diet groups: offspring from RD dams weaned to a RD and offspring from HFD dams weaned to a RD or to an HFD (IHH). In both males and females, only IHH increased systolic BP, but IUGR and HFD both alone and in combination increased arterial stiffness. Aortas contained fewer but thicker elastin bands in IHH rats and IUGR offspring from dams fed an HFD and weaned to a regular diet. IHH increased aortic lysl oxidase protein. In summary, the PND 21 rat mediators of vascular remodeling from IUGR and maternal HFD normalize by PND 60 while changes in elastin and arterial stiffness persist. We speculate that the longer-term risk of hypertension from dietary mediators is augmented by underlying IUGR-induced structural changes to the extracellular matrix. NEW & NOTEWORTHY We report that a combined insult of intrauterine growth restriction and maternal high-fat diet increases the risk of early cardiovascular pathology both independently and in conjunction with a continued high-fat diet in offspring.

Intrauterine growth-restricted (IUGR) fetal sheep have increased hepatic glucose production (HGP) that is resistant to suppression during a hyperinsulinemic-isoglycemic clamp (insulin clamp). We hypothesized that the IUGR fetal liver would have activation of metabolic and signaling pathways that support HGP and inhibition of insulin-signaling pathways. To test this, we used transcriptomic profiling with liver samples from control (CON) and IUGR fetuses receiving saline or an insulin clamp. The IUGR liver had upregulation of genes associated with gluconeogenesis/glycolysis, transcription factor regulation, and cytokine responses and downregulation of genes associated with cholesterol synthesis, amino acid degradation, and detoxification pathways. During the insulin clamp, genes associated with cholesterol synthesis and innate immune response were upregulated in CON and IUGR. There were 20-fold more genes differentially expressed during the insulin clamp in IUGR versus CON. These genes were associated with proteasome activation and decreased amino acid and lipid catabolism. We found increased TRB3, JUN , MYC , and SGK1 expression and decreased PTPRD expression as molecular targets for increased HGP in IUGR. As candidate genes for resistance to insulin's suppression of HGP, expression of JUN , MYC , and SGK1 increased more during the insulin clamp in CON compared with IUGR. Metabolites were measured with 1 H-nuclear magnetic resonance and support increased amino acid concentrations, decreased mitochondria activity and energy state, and increased cell stress in the IUGR liver. These results demonstrate a robust response, beyond suppression of HGP, during the insulin clamp and coordinate responses in glucose, amino acid, and lipid metabolism in the IUGR fetus.

The main objective of these studies was to characterize metabolic, body composition, and cardiovascular responses to a free-choice high-fat, high-sucrose diet in female cycling and pregnant rats. In the nonpregnant state, female Sprague-Dawley rats offered a 3-wk free-choice high-fat, high-sucrose diet had greater energy intake, adiposity, serum leptin, and triglyceride concentrations compared with rats fed with standard chow and developed glucose intolerance. In addition, choice-diet-fed rats had larger cardiac ventricular weights, smaller kidney and pancreas weights, and higher blood pressure than chow-fed rats, but they did not exhibit resistance artery endothelial dysfunction. When the free-choice diet continued throughout pregnancy, rats remained hyperphagic, hyperleptinemic, and obese. Choice pregnant rats exhibited uterine artery endothelial dysfunction and had smaller fetuses compared with chow pregnant rats. Pregnancy normalized mean arterial blood pressure and pancreas weights in choice rats. These studies are the first to provide a comprehensive evaluation of free-choice high-fat, high-sucrose diet on metabolic and cardiovascular functions in female rats, extending the previous studies in males to female cycling and pregnant rodents. Free-choice diet may provide a new model of preconceptual maternal obesity to study the role of increased energy intake, individual food components, and preexisting maternal obesity on maternal and offspring physiological responses during pregnancy and after birth.

Maternal hypertension during pregnancy is a major risk factor for intrauterine growth restriction (IUGR), which increases susceptibility to cardiovascular and metabolic disease in adulthood through unclear mechanisms. The aim of this study was to characterize the pancreatic β-cell area and function in the fetal rat offspring of a reduced uterine perfusion pressure (RUPP) model of gestational hypertension. At embryonic day 19.5, RUPP dams exhibited lower body weight, elevated mean blood pressure, reduced litter size, and higher blood glucose compared with sham-operated controls. In RUPP placental lysates, a nonsignificant change in mammalian target of rapamycin (mTOR) activity markers, phosphorylated S6 at serine 240, and phosphorylated AKT (at S473) was observed. RUPP offspring showed significantly reduced β-cell-to-pancreas area and increased β-cell death but normal insulin levels in serum. Isolated islets had normal insulin content and secretory function in response to glucose and palmitate. Fetal pancreatic lysates showed a tendency for reduced insulin levels, with a significant reduction in total mTOR protein with RUPP surgery. In addition, its downstream complex 2 targets phosphorylation of AKT at S473, and pAKT at Thr 308 tended to be reduced in the fetal RUPP pancreas. Altogether, these data show that RUPP offspring demonstrated increased β-cell death, reduced β-cell area, and altered nutrient-sensor mTOR protein level in the pancreas. This could represent a mechanistic foundation in IUGR offspring's risk for enhanced susceptibility to type 2 diabetes and other metabolic vulnerabilities seen in adulthood.

The prevalence of obesity and type 2 (T2D) diabetes is a major health concern in the United States and around the world. T2D is a complex disease characterized by pancreatic β-cell failure in association with obesity and insulin resistance in peripheral tissues. Although several genes associated with T2D have been identified, it is speculated that genetic variants account for only <10% of the risk for this disease. A strong body of data from both human epidemiological and animal studies shows that fetal nutrient factors in utero confer significant susceptibility to T2D. Numerous studies done in animals have shown that suboptimal maternal environment or placental insufficiency causes intrauterine growth restriction (IUGR) in the fetus, a critical factor known to predispose offspring to obesity and T2D, in part by causing permanent consequences in total functional β-cell mass. This review will focus on the potential contribution of the placenta in fetal programming of obesity and TD and its likely impact on pancreatic β-cell development and growth.

Intrauterine growth restriction (IUGR) is a risk factor for neonatal chronic lung disease (CLD) characterized by reduced alveoli and perturbed matrix remodeling. Previously, our group showed an activation of myofibroblasts and matrix remodeling in rat lungs after IUGR. Because growth hormone (GH) and insulin-like growth factor I (IGF-I) regulate development and growth, we queried 1) whether GH/IGF-I signaling is dysregulated in lungs after IUGR and 2) whether GH/IGF-I signaling is linked to neonatal lung myofibroblast function. IUGR was induced in Wistar rats by isocaloric low-protein diet during gestation. Lungs were obtained at embryonic day (E) 21, postnatal day (P) 3, P12, and P23. Murine embryonic fibroblasts (MEF) or primary neonatal myofibroblasts from rat lungs of control (pnF Co ) and IUGR (pnF IUGR ) were used for cell culture studies. In the intrauterine phase (E21), we found a reduction in GH receptor (GH-R), Stat5 signaling and IGF-I expression in lungs after IUGR. In the postnatal phase (P3-P23), catchup growth after IUGR was linked to increased GH mRNA, GH-R protein, activation of proliferative Stat5/Akt signaling, cyclin D1 and PCNA in rat lungs. On P23, a thickening of the alveolar septae was related to increased vimentin and matrix deposition, indicating fibrosis. In cell culture studies, nutrient deprivation blocked GH-R/IGF-IR signaling and proliferation in MEFs; this was reversed by IGF-I. Proliferation and Stat5 activation were increased in pnF IUGR . IGF-I and GH induced proliferation and migration of pnF Co ; only IGF-I had these effects on pnF IUGR . Thus, we show a novel mechanism by which the GH/IGF-I axis in lung myofibroblasts could account for structural lung changes after IUGR.

Intrauterine growth restriction (IUGR) in premature newborns increases the risk for bronchopulmonary dysplasia, a chronic lung disease characterized by disrupted pulmonary angiogenesis and alveolarization. We previously showed that experimental IUGR impairs angiogenesis; however, mechanisms that impair pulmonary artery endothelial cell (PAEC) function are uncertain. The NF-κB pathway promotes vascular growth in the developing mouse lung, and we hypothesized that IUGR disrupts NF-κB-regulated proangiogenic targets in fetal PAEC. PAECs were isolated from the lungs of control fetal sheep and sheep with experimental IUGR from an established model of chronic placental insufficiency. Microarray analysis identified suppression of NF-κB signaling and significant alterations in extracellular matrix (ECM) pathways in IUGR PAEC, including decreases in collagen 4α1 and laminin α4, components of the basement membrane and putative NF-κB targets. In comparison with controls, immunostaining of active NF-κB complexes, NF-κB-DNA binding, baseline expression of NF-κB subunits p65 and p50, and LPS-mediated inducible activation of NF-κB signaling were decreased in IUGR PAEC. Although pharmacological NF-κB inhibition did not affect angiogenic function in IUGR PAEC, angiogenic function of control PAEC was reduced to a similar degree as that observed in IUGR PAEC. These data identify reductions in endothelial NF-κB signaling as central to the disrupted angiogenesis observed in IUGR, likely by impairing both intrinsic PAEC angiogenic function and NF-κB-mediated regulation of ECM components necessary for vascular development. These data further suggest that strategies that preserve endothelial NF-κB activation may be useful in lung diseases marked by disrupted angiogenesis such as IUGR.

Individuals born after intrauterine growth restriction (IUGR) are at increased risk of developing cardiovascular diseases in adulthood, notably hypertension (HTN). Alterations in the vascular system, particularly impaired endothelium-dependent vasodilation, may play an important role in long-term effects of IUGR. Whether such vascular dysfunction precedes HTN has not been fully established in individuals born after IUGR. Moreover, the intimate mechanisms of altered endothelium-dependent vasodilation remain incompletely elucidated. We therefore investigated, using a rat model of IUGR, whether impaired endothelium-dependent relaxation precedes the development of HTN and whether key components of the l-arginine-nitric oxide (NO) pathway are involved in its pathogenesis. Pregnant rats were fed with a control (CTRL, 23% casein) or low-protein diet (LPD, 9% casein) to induce IUGR. Systolic blood pressure (SBP) was measured by tail-cuff plethysmography in 5- and 8-wk-old male offspring. Aortic rings were isolated to investigate relaxation to acetylcholine, NO production, endothelial NO synthase (eNOS) protein content, arginase activity, and superoxide anion production. SBP was not different at 5 wk but significantly increased in 8-wk-old offspring of maternal LPD (LP) versus CTRL offspring. In 5-wk-old LP versus CTRL males, endothelium-dependent vasorelaxation was significantly impaired but restored by preincubation with l-arginine or the arginase inhibitor S-(2-boronoethyl)-l-cysteine; NO production was significantly reduced but restored by l-arginine pretreatment; total eNOS protein, dimer-to-monomer ratio, and arginase activity were significantly increased; superoxide anion production was significantly enhanced but normalized by pretreatment with the NO synthase inhibitor N ω -nitro-l-arginine. In this model, IUGR leads to early-impaired endothelium-dependent vasorelaxation, resulting from arginase upregulation and eNOS uncoupling, which precedes the development of HTN.

Poor prenatal development, followed by rapid childhood growth, conveys greater cardiometabolic risk in later life. Microswine offspring exposed to perinatal maternal protein restriction [MPR; "low protein offspring" (LPO)] grow poorly in late-fetal/neonatal stages. After weaning to an ad libitum (AL) diet, LPO-AL exhibit accelerated growth and fat deposition rates with low adiponectin mRNA, despite low-normal body fat and small intra-abdominal adipocytes. We examined effects of caloric restriction (CR) on growth and metabolic status in LPO and normal protein offspring (NPO) randomized to AL or CR diets from weaning. CR transiently reduced growth in both LPO and NPO, delaying recovery in female LPO-CR. Over 7.5-12.5 weeks, linear growth rates in LPO-CR were slower than LPO-AL ( P < 0.001) but exceeded NPO-AL; body weight growth rates fell but were lower in LPO-CR versus NPO-CR. Linear acceleration ceased after 12 weeks. At 16 weeks, percent catch-up in LPO-CR was reduced versus LPO-AL ( P < 0.001). Plasma growth hormone was low in LPO ( P < 0.02). CR normalized fat deposition rate, yet adiponectin mRNA remained low in LPO-CR ( P < 0.001); plasma adiponectin was low in all LPO-AL and in female LPO-CR. Insulin sensitivity improved during CR. We conclude that in LPO: 1) CR delays onset of, but does not abolish, accelerated linear growth, despite low growth hormone; 2) CR yields stunting via delayed onset, plus a finite window for linear growth acceleration; 3) MPR lowers adiponectin mRNA independently of growth, adiposity, or adipocyte size; and 4) MPR reduces circulating adiponectin in LPO-AL and female LPO-CR, potentially enhancing cardiometabolic risk.

Intrauterine growth restriction (IUGR) increases the risk of ischemic heart disease in adulthood. Studies in rats suggest cardiac vulnerability is more pronounced in males and in offspring that were exposed to hypoxia in utero. Therefore, we aimed to test the hypotheses that 1) IUGR adolescent males, but not females, have fewer cardiomyocytes and altered expression of cardiometabolic genes compared with controls; and 2) IUGR due to hypoxia has a greater effect on these parameters compared with IUGR due to nutrient restriction. IUGR was induced in guinea pigs by maternal hypoxia (MH; 10% O 2 , n = 9) or maternal nutrient restriction (MNR; ~30% reduction in food intake, n = 9) in the second half of pregnancy and compared with control ( n = 11). At 120 days of age, postmortem was performed and the left ventricle perfusion fixed for stereological determination of cardiomyocyte number or snap frozen to determine the abundance of cardiometabolic genes and proteins by quantitative RT-PCR and Western blotting, respectively. MH reduced the number of cardiomyocytes in female ( P < 0.05), but not male or MNR, adolescent offspring. Furthermore, IUGR males had decreased expression of genes responsible for fatty acid activation in the sarcoplasm ( FACS) and transport into the mitochondria ( AMPK-a 2 and ACC; P < 0.05) and females exposed to MH had increased activation/phosphorylation of AMP-activated protein kinase-α ( P < 0.05). We postulate that the changes in cardiomyocyte endowment and cardiac gene expression observed in the present study are a direct result of in utero programming, as offspring at this age did not suffer from obesity, hypertension, or left ventricular hypertrophy.

We determined the impact of moderate maternal nutrient restriction (MNR) in guinea pigs with fetal growth restriction (FGR) on offspring body and organ weights, hypothesizing that FGR-MNR animals will show catch-up growth but with organ-specific differences. Guinea pig sows were fed ad libitum (Control) or 70% of the control diet from 4 weeks preconception, switching to 90% at midpregnancy (MNR). Control newborns >95 g [appropriate for gestational age (AGA); n = 37] and MNR newborns <85 g (FGR; n = 37) were monitored until neonatal (~25 days) or adult (~110 days) necropsy. Birth weights and body/organ weights at necropsy were used to calculate absolute and fractional growth rates (FRs). FGR-MNR birth weights were decreased ~32% compared with the AGA-Controls. FGR-MNR neonatal whole body FRs were increased ~36% compared with Controls indicating catch-up growth, with values negatively correlated to birth weights indicating the degree of FGR leads to greater catch-up growth. However, the increase in organ FRs in the FGR-MNR neonates compared with Controls was variable, being similar for the brain and kidneys indicating comparable catch-up growth to that of the whole body and twofold increased for the liver but negligible for the heart indicating markedly increased and absent catch-up growth, respectively. While FGR-MNR body and organ weights were unchanged from the AGA-Controls by adulthood, whole body growth rates were increased. These findings confirm early catch-up growth in FGR-MNR guinea pigs but with organ-specific differences and enhanced growth rates by adulthood, which are likely to have implications for structural alterations and disease risk in later life.

Females born growth restricted have poor adult bone health. Stress exposure during pregnancy increases risk of pregnancy complications. We determined whether maternal stress exposure in growth-restricted females exacerbates long-term maternal and offspring bone phenotypes. On gestational day 18, bilateral uterine vessel ligation (restricted) or sham (control) surgery was performed on Wistar-Kyoto rats. At 4 mo, control and restricted females were mated and allocated to unstressed or stressed pregnancies. Stressed pregnancies had physiological measurements performed; unstressed females were not handled. After birth, mothers were aged to 13 mo. Second-generation (F2) offspring generated four experimental groups: control unstressed, restricted unstressed, control stressed and restricted stressed. F2 offspring were studied at postnatal day 35 (PN35), 6, 12, and 16 mo. Peripheral quantitative computed tomography was performed on maternal and F2 offspring femurs. Restricted females, irrespective of stress during pregnancy, had decreased endosteal circumference, bending strength, and increased osteocalcin concentrations after pregnancy at 13 mo. F2 offspring of stressed mothers were born lighter. F2 male offspring from stressed pregnancies had decreased trabecular content at 6 mo and decreased endosteal circumference at 16 mo. F2 female offspring from growth-restricted mothers had reduced cortical thickness at PN35 and reduced endosteal circumference at 6 mo. At 12 mo, females from unstressed restricted and stressed control mothers had decreased trabecular content. Low birth weight females had long-term bone changes, highlighting programming effects on bone health. Stress during pregnancy did not exacerbate these programmed effects. Male and female offspring responded differently to maternal growth restriction and stress, indicating gender-specific programming effects.

Placental hypoxia is associated with maternal hypertension, placental insufficiency, and fetal growth restriction. In the pregnant guinea pig, prenatal hypoxia during early gestation inhibits cytotrophoblast invasion of spiral arteries, increases maternal blood pressure, and induces fetal growth restriction. In this study the impact of chronic maternal hypoxia on fetal heart structure was evaluated using four-dimensional echocardiography with spatiotemporal image correlation and tomographic ultrasound, and uterine and umbilical artery resistance/pulsatility indexes and fetal heart function were evaluated using pulsed-wave Doppler ultrasound. Pregnant guinea pigs were exposed to normoxia ( n = 7) or hypoxia (10.5% O 2 , n = 9) at 28-30 days gestation, which was maintained until full term (65 days). At full term, fetal heart structure and outflow tracts were evaluated in the four-chamber view. Fetal heart diastolic function was assessed by E wave-to-A wave diastolic filling ratios (E/A ratios) of both ventricles and systolic function by the myocardial performance index (or Tie) of left ventricles of normoxic ( n = 21) and hypoxic ( n = 17) fetuses. There were no structural abnormalities in fetal hearts. However, hypoxia induced asymmetric fetal growth restriction and increased the placental/fetal weight compared with normoxic controls. Hypoxia increased Doppler resistance and pulsatility indexes in the uterine, but not umbilical, arteries, had no effect on the Tie index, and increased the E/A ratio in left, but not right, ventricles. Thus, prolonged hypoxia, starting at midgestation, increases uterine artery resistance and generates fetal growth restriction at full term. Furthermore, the enhanced cardiac diastolic filling with no changes in systolic function or umbilical artery resistance suggests that the fetal guinea pig systemic circulation undergoes a compensated, adaptive response to prolonged hypoxia exposure., (Copyright © 2017 the American Physiological Society.)

Intrauterine growth restriction (IUGR) is associated with persistent metabolic complications, but information is limited for IUGR infants. We determined glucose-stimulated insulin secretion (GSIS) and insulin sensitivity in young lambs with placental insufficiency-induced IUGR. Lambs with hyperthermia-induced IUGR ( n = 7) were compared with control lambs ( n = 8). GSIS was measured at 8 ± 1 days of age, and at 15 ± 1 days, body weight-specific glucose utilization rates were measured with radiolabeled d-glucose during a hyperinsulinemic-euglycemic clamp (HEC). IUGR lambs weighed 23% less ( P < 0.05) than controls at birth. Fasting plasma glucose and insulin concentrations were not different between IUGR and controls for either study. First-phase insulin secretion was enhanced 2.3-fold in IUGR lambs compared with controls. However, second-phase insulin concentrations, glucose-potentiated arginine-stimulated insulin secretion, and β-cell mass were not different, indicating that IUGR β-cells have an intrinsic enhancement in acute GSIS. Compared with controls, IUGR lambs had higher body weight-specific glucose utilization rates and greater insulin sensitivity at fasting (1.6-fold) and hyperinsulinemic periods (2.4-fold). Improved insulin sensitivity for glucose utilization was not due to differences in skeletal muscle insulin receptor and glucose transporters 1 and 4 concentrations. Plasma lactate concentrations during HEC were elevated in IUGR lambs compared with controls, but no differences were found for glycogen content or citrate synthase activity in liver and muscle. Greater insulin sensitivity for glucose utilization and enhanced acute GSIS in young lambs are predicted from fetal studies but may promote conditions that exaggerate glucose disposal and lead to episodes of hypoglycemia in IUGR infants., (Copyright © 2017 the American Physiological Society.)

Intrauterine growth restriction (IUGR) increases the incidence of adult cardiovascular disease (CVD). The sex-specific developmental mechanisms for IUGR-induced and Western high-fat diet (HFD) modification of CVD remain poorly understood. We hypothesized a maternal HFD in the Sprague-Dawley rat would augment IUGR-induced CVD in the offspring through decreased cardiac function and increased extracellular matrix (ECM) remodeling and stiffness in a sex-specific manner. HFD or regular diet (Reg) was given from 5 wk before mating through postnatal day (PND) 21. IUGR was induced by uterine artery ligation at embryonic day 19.5 (term = 21.5 days). At PND 21, echocardiographic assessments were made and carotid arteries tested for vascular compliance using pressure myography. Arterial samples were quantified for ECM constituents or fixed for histologic evaluation. The insult of IUGR (IUGR + Reg and IUGR + HFD) led to increased mechanical stiffness in both sexes (P < 0.05). The combination of IUGR + HFD increased diastolic blood pressure 47% in males (M) and 35% in females (F) compared with the Con + Reg (P < 0.05). ECM remodeling in IUGR + HFD caused fewer (M = -29%, F = -24%) but thicker elastin bands (M = 18%, F = 18%) and increased total collagen (M = 49%, F = 34%) compared with Con + Reg arteries. Remodeling in IUGR + HFD males increased medial collagen and soluble collagen (P < 0.05). Remodeling in IUGR + HFD females increased adventitial collagen and wall thickness (P < 0.05) and decreased matrix metalloproteinase 2 (MMP-2), advanced glycosylation end products (AGE), and receptor AGE (RAGE; P < 0.05). In summary, both IUGR + Reg and IUGR + HFD remodel ECM in PND 21 rats. While IUGR + HFD increases blood pressure, IUGR but not HFD increases vascular stiffness suggesting a specific mechanism of vascular remodeling that can be targeted to limit future disease., New & Noteworthy: We report intrauterine growth restriction (IUGR) increases vascular stiffening in both male and female rats through increased collagen content and altered elastin structure more than a high-fat diet (HFD) alone. Our study shows the importance of stiffness supporting the hypothesis that there are physiologic differences and potential windows for early intervention targeting vascular remodeling mechanisms., (Copyright © 2017 the American Physiological Society.)

Preeclampsia (PE) is pregnancy-induced hypertension with proteinuria that typically develops after 20 wk of gestation. Antihypertensives currently used for PE reduce blood pressure of PE mothers but do not prevent preterm delivery and do not alleviate fetal growth restriction (FGR) associated with PE. We have recently shown that the activation of the endothelin (ET) system exacerbates PE. However, ET receptor antagonists are teratogenic and not suitable for pregnant women. The vitamin B 3 nicotinamide (Nam) inhibits vasoconstriction by ET and is generally considered safe and harmless to babies. Nam also alleviates oxidative stress, which exacerbates PE and FGR. The aim of the present study was to evaluate therapeutic effects of Nam on the PE-like phenotype using a reduced uterine perfusion pressure (RUPP) model in mice that we have recently developed. We bilaterally ligated uterine vessels of pregnant mice and administered Nam or water daily by gavage. Nam improved maternal hypertension, proteinuria, and glomerular endotheliosis in RUPP mice. Moreover, Nam prolonged pregnancies and improved survival and growth of the embryos in RUPP PE mice. In conclusion, Nam alleviates the PE-like phenotype and FGR in the murine RUPP model. Nam could help treat maternal hypertension and FGR in human PE., (Copyright © 2017 the American Physiological Society.)

Intrauterine growth restriction (IUGR) is a common pregnancy complication and is a leading cause of fetal morbidity and mortality. Placental hypoxia contributes to adverse fetal consequences, such as IUGR. Exposing pregnant rats to hypoxia can lead to IUGR; however, assessment of maternal vascular function in a rat model of hypoxia, and the mechanisms that may contribute to adverse pregnancy outcomes, has not been extensively studied. We hypothesized that exposing pregnant rats to hypoxia will affect maternal systemic vascular function and increase the uterine artery resistance index (RI), which will be associated with IUGR. To test this hypothesis, pregnant rats were kept in normoxia (21% O 2 ) or hypoxia (11% O 2 ) from gestational day (GD) 6 to 20 Maternal blood pressure, uteroplacental resistance index (RI) (ultrasound biomicroscopy), and vascular function (wire myography) were assessed in uterine and mesenteric arteries. Fetal weight was significantly reduced (P < 0.001), while maternal blood pressure was increased (P < 0.05) in rats exposed to hypoxia. Maternal vascular function was also affected after exposure to hypoxia, including impaired endothelium-dependent vasodilation responses to methacholine in isolated uterine arteries (pEC 50 normoxia: 6.55 ± 0.23 vs. hypoxia: 5.02 ± 0.35, P < 0.01) and a reduced uterine artery RI in vivo (normoxia: 0.63 ± 0.04 vs. hypoxia: 0.53 ± 0.01, P < 0.05); associated with an increase in umbilical vein RI (normoxia: 0.35 ± 0.02 vs. hypoxia: 0.45 ± 0.04, P < 0.05). These data demonstrate maternal and fetal alterations in vascular function due to prenatal exposure to hypoxia. Further, although there was a compensatory reduction in uterine artery RI in the hypoxia groups, this was not sufficient to prevent IUGR., (Copyright © 2016 the American Physiological Society.)

The effect of hypoxia on cellular metabolism is well documented in adult vertebrates, but information is entirely lacking for embryonic organisms. The effect of hypoxia on embryonic physiology is particularly interesting, as metabolic responses during development may have life-long consequences, due to developmental plasticity. To this end, we investigated the effects of chronic developmental hypoxia on cardiac mitochondrial function in embryonic and juvenile American alligators (Alligator mississippiensis). Alligator eggs were incubated in 21% or 10% oxygen from 20 to 90% of embryonic development. Embryos were either harvested at 90% development or allowed to hatch and then reared in 21% oxygen for 3 yr. Ventricular mitochondria were isolated from embryonic/juvenile alligator hearts. Mitochondrial respiration and enzymatic activities of electron transport chain complexes were measured with a microrespirometer and spectrophotometer, respectively. Developmental hypoxia induced growth restriction and increased relative heart mass, and this phenotype persisted into juvenile life. Embryonic mitochondrial function was not affected by developmental hypoxia, but at the juvenile life stage, animals from hypoxic incubations had lower levels of Leak respiration and higher respiratory control ratios, which is indicative of enhanced mitochondrial efficiency. Our results suggest developmental hypoxia can have life-long consequences for alligator morphology and metabolic function. Further investigations are necessary to reveal the adaptive significance of the enhanced mitochondrial efficiency in the hypoxic phenotype., (Copyright © 2016 the American Physiological Society.)

Limited nutrient availability is a cause of intrauterine growth restriction (IUGR), a condition that has important implications for the well being of the offspring. Using the established IUGR model of maternal fasting in the rat, we investigated mechanisms that control gene expression and mRNA translation in late-gestation fetal liver. Maternal fasting for 48 h during the last one-third of gestation was associated with a 10-15% reduction in fetal body weight and a disproportionate one-third reduction in total fetal liver protein. The fetal liver transcriptome showed only subtle changes consistent with reduced cell proliferation and enhanced differentiation in IUGR. Effects on the transcriptome could not be attributed to specific transcription factors. We purified translating polysomes to profile the population of mRNAs undergoing active translation. Microarray analysis of the fetal liver translatome indicated a global reduction of translation. The only targeted effect was enhanced translation of mitochondrial ribosomal proteins in IUGR, consistent with enhanced mitochondrial biogenesis. There was no evidence for attenuated signaling through the mammalian target of rapamycin (mTOR). Western blot analysis showed no changes in fetal liver mTOR signaling. However, eukaryotic initiation factor 2α (eIF2α) phosphorylation was increased in livers from IUGR fetuses, consistent with a role in global translation control. Our data indicate that IUGR-associated changes in hepatic gene expression and mRNA translation likely involve a network of complex regulatory mechanisms, some of which are novel and distinct from those that mediate the response of the liver to nutrient restriction in the adult rat., (Copyright © 2016 the American Physiological Society.)

Many studies report sexual dimorphism in the fetal programming of adult disease. We hypothesized that there would be differences in the age-related decline in renal function between male and female intrauterine growth-restricted rats. Early-life growth restriction was induced in rat offspring by administering a low-protein diet (LPD; 8.7% casein) to dams during pregnancy and lactation. Control dams were fed a normal-protein diet (NPD; 20% casein). Mean arterial pressure (MAP) and renal structure and function were assessed in 32- and 100-wk-old offspring. Mesenteric artery function was examined at 100 wk using myography. At 3 days of age, body weight was ∼24% lower (P < 0.0001) in LPD offspring; this difference was still apparent at 32 wk but not at 100 wk of age. MAP was not different between the male NPD and LPD groups at either age. However, MAP was greater in LPD females compared with NPD females at 100 wk of age (∼10 mmHg; P < 0.001). Glomerular filtration rate declined with age in the NPD male, LPD male and LPD female offspring (∼45%, all P < 0.05), but not in NPD female offspring. Mesenteric arteries in the aged LPD females had reduced sensitivity to nitric oxide donors compared with their NPD counterparts, suggesting that vascular dysfunction may contribute to the increased risk of disease in aged females. In conclusion, females growth-restricted in early life were no longer protected from an age-related decline in renal and arterial function, and this was associated with increased arterial pressure without evidence of renal structural damage., (Copyright © 2015 the American Physiological Society.)

Intrauterine growth restriction increases the risk of perinatal complications and predisposes the infant to diabetes and cardiovascular disease in later life. Mechanisms by which maternal nutrient restriction (MNR) reduces fetal growth are poorly understood. We hypothesized that MNR decreases placental amino acid (AA) transporter activity, leading to reduced transplacental transfer of AAs. Pregnant baboons were fed either a control (ad libitum, n = 7), or MNR diet (70% of control diet, n = 7) from gestational day (GD) 30. At GD 165 (0.9 gestation), placentas (n = 7 in each group) were collected, and microvillous plasma membrane vesicles (MVM) isolated. MVM system A and system L AA transport was determined in vitro using radiolabeled substrates and rapid filtration techniques. In vivo transplacental AA transport was assessed by infusing nine (13)C- or (2)H-labeled essential AA as a bolus into the maternal circulation (n = 5 control, n = 4 MNR) at cesarean section. A fetal vein-to-maternal artery mole percent excess ratio for each essential AA was calculated. Fetal and placental weights were significantly reduced in the MNR group compared with controls (P < 0.01). The activity of system A and system L was markedly reduced by 73 and 84%, respectively, in MVM isolated from baboon placentas at GD 165 following MNR (P < 0.01). In vivo, the fetal vein-to-maternal artery mole percent excess ratio was significantly reduced for leucine, isoleucine, methionine, phenylalanine, threonine, and tryptophan in MNR baboons (P < 0.05). This is the first study to investigate placental AA transport in a nonhuman primate model of MNR. We demonstrate that the downregulation of system A and system L activity in syncytiotrophoblast MVM in MNR leads to decreased transplacental AA transport and, consequently, reduced circulating fetal AA concentrations, a potential mechanism linking maternal undernutrition to reduced fetal growth., (Copyright © 2015 the American Physiological Society.)

Intrauterine growth restriction (IUGR) has been associated with increased susceptibility to myocardial ischemia-reperfusion (I/R) injury. Exercise is an effective preventive intervention for cardiovascular diseases; however, it may be detrimental in conditions of compromised health. The aim of this study was to determine whether exercise training can improve cardiac performance after I/R injury in IUGR offspring. We used a hypoxia-induced IUGR model by exposing pregnant Sprague-Dawley rats to 21% oxygen (control) or hypoxic (11% oxygen; IUGR) conditions from gestational day 15 to 21. At 10 wk of age, offspring were randomized to a sedentary group or to a 6-wk exercise protocol. Transthoracic echocardiography assessments were performed after 6 wk. Twenty-four hours after the last bout of exercise, ex vivo cardiac function was determined using a working heart preparation. With exercise training, there was improved baseline cardiac performance in male control offspring but a reduced baseline cardiac performance in male IUGR exercised offspring (P < 0.05). In male offspring, exercise decreased superoxide generation in control offspring, while in IUGR offspring, it had the polar opposite effect (interaction P ≤ 0.05). There was no effect of IUGR or exercise on cardiac function in female offspring. In conclusion, in male IUGR offspring, exercise may be a secondary stressor on cardiac function. A reduction in cardiac performance along with an increase in superoxide production in response to exercise was observed in this susceptible group., (Copyright © 2015 the American Physiological Society.)

Intrauterine growth restriction (IUGR) increases the risk for neurodevelopment delay and neuroendocrine reprogramming in both humans and rats. Neuroendocrine reprogramming involves the glucocorticoid receptor (GR) gene that is epigenetically regulated in the hippocampus. Using a well-characterized rodent model, we have previously shown that IUGR increases GR exon 1.7 mRNA variant and total GR expressions in male rat pup hippocampus. Epigenetic regulation of GR transcription may involve chromatin remodeling of the GR gene. A key chromatin remodeler is Brahma-related gene-1(Brg1), a member of the ATP-dependent SWItch/Sucrose NonFermentable (SWI/SNF) chromatin remodeling complex. Brg1 regulates gene expression by affecting nucleosome repositioning and recruiting transcriptional components to target promoters. We hypothesized that IUGR would increase hippocampal Brg1 expression and binding to GR exon 1.7 promoter, as well as alter nucleosome positioning over GR promoters in newborn male pups. Further, we hypothesized that IUGR would lead to accumulation of specificity protein 1 (Sp1) and RNA pol II at GR exon 1.7 promoter. Indeed, we found that IUGR increased Brg1 expression and binding to GR exon 1.7 promoter. We also found that increased Brg1 binding to GR exon 1.7 promoter was associated with accumulation of Sp1 and RNA pol II carboxy terminal domain pSer-5 (a marker of active transcription). Furthermore, the transcription start site of GR exon 1.7 was located within a nucleosome-depleted region. We speculate that changes in hippocampal Brg1 expression mediate GR expression and subsequently trigger neuroendocrine reprogramming in male IUGR rats., (Copyright © 2015 the American Physiological Society.)

Angiotensin-converting enzyme 2 (ACE2) knockout is associated with reduced fetal weight at late gestation; however, whether uteroplacental vascular and/or hemodynamic disturbances underlie this growth-restricted phenotype is unknown. Uterine artery reactivity and flow velocities, umbilical flow velocities, trophoblast invasion, and placental hypoxia were determined in ACE2 knockout (KO) and C57Bl/6 wild-type (WT) mice at day 14 of gestation. Although systolic blood pressure was higher in pregnant ACE2 KO vs. WT mice (102.3 ± 5.1 vs. 85.1 ± 1.9 mmHg, n = 5-6), the magnitude of difference was similar to that observed in nonpregnant ACE2 KO vs. WT mice. Maternal urinary protein excretion, serum creatinine, and kidney or heart weights were not different in ACE2 KO vs. WT. Fetal weight and pup-to-placental weight ratio were lower in ACE2 KO vs. WT mice. A higher sensitivity to Ang II [pD2 8.64 ± 0.04 vs. 8.5 ± 0.03 (-log EC50)] and greater maximal contraction to phenylephrine (169.0 ± 9.0 vs. 139.0 ± 7.0% KMAX), were associated with lower immunostaining for Ang II receptor 2 and fibrinoid content of the uterine artery in ACE2 KO mice. Uterine artery flow velocities and trophoblast invasion were similar between study groups. In contrast, umbilical artery peak systolic velocities (60.2 ± 4.5 vs. 75.1 ± 4.5 mm/s) and the resistance index measured using VEVO 2100 ultrasound were lower in the ACE2 KO vs. WT mice. Immunostaining for pimonidazole, a marker of hypoxia, and hypoxia-inducible factor-2α were higher in the trophospongium and placental labyrinth of the ACE2 KO vs. WT. In summary, placental hypoxia and uterine artery dysfunction develop before major growth of the fetus occurs and may explain the fetal growth restricted phenotype., (Copyright © 2015 the American Physiological Society.)

The mechanisms of the pathogenesis of preeclampsia, a leading cause of maternal morbidity and death worldwide, are poorly understood in part due to a lack of spontaneous animal models of the disease. We hypothesized that the Dahl salt-sensitive (S) rat, a genetic model of hypertension and kidney disease, is a spontaneous model of superimposed preeclampsia. The Dahl S was compared with the Sprague-Dawley (SD) rat, a strain with a well-characterized normal pregnancy, and the spontaneously hypertensive rat (SHR), a genetic model of hypertension that does not experience a preeclamptic phenotype despite preexisting hypertension. Mean arterial pressure (MAP, measured via telemetry) was elevated in the Dahl S and SHR before pregnancy, but hypertension was exacerbated during pregnancy only in Dahl S. In contrast, SD and SHR exhibited significant reductions in MAP consistent with normal pregnancy. Dahl S rats exhibited a severe increase in urinary protein excretion, glomerulomegaly, increased placental hypoxia, increased plasma soluble fms-like tyrosine kinase-1 (sFlt-1), and increased placental production of tumor necrosis factor-α (TNF-α). The Dahl S did not exhibit the expected decrease in uterine artery resistance during late pregnancy in contrast to the SD and SHR. Dahl S pups and litter sizes were smaller than in the SD. The Dahl S phenotype is consistent with many of the characteristics observed in human superimposed preeclampsia, and we propose that the Dahl S should be considered further as a spontaneous model to improve our understanding of the pathogenesis of superimposed preeclampsia and to identify and test new therapeutic targets for its treatment., (Copyright © 2015 the American Physiological Society.)

In the fetus, there is a redistribution of cardiac output in response to acute hypoxemia, to maintain perfusion of key organs, including the brain, heart, and adrenal glands. There may be a similar redistribution of cardiac output in the chronically hypoxemic, intrauterine growth-restricted fetus. Surgical removal of uterine caruncles in nonpregnant ewe results in the restriction of placental growth (PR) and intrauterine growth. Vascular catheters were implanted in seven control and six PR fetal sheep, and blood flow to organs was determined using microspheres. Placental and fetal weight was significantly reduced in the PR group. Despite an increase in the relative brain weight in the PR group, there was no difference in blood flow to the brain between the groups, although PR fetuses had higher blood flow to the temporal lobe. Adrenal blood flow was significantly higher in PR fetuses, and there was a direct relationship between mean gestational PaO2 and blood flow to the adrenal gland. There was no change in blood flow, but a decrease in oxygen and glucose delivery to the heart in the PR fetuses. In another group, there was a decrease in femoral artery blood flow in the PR compared with the Control group, and this may support blood flow changes to the adrenal and temporal lobe. In contrast to the response to acute hypoxemia, these data show that there is a redistribution of blood flow to the adrenals and temporal lobe, but not the heart or whole brain, in chronically hypoxemic PR fetuses in late gestation., (Copyright © 2015 the American Physiological Society.)

Fetal growth restriction (FGR) affects 3-8% of human pregnancies. Mouse models have provided important etiological data on FGR; they permit the assessment of treatment strategies on the physiological function of both mother and her developing offspring. Our study aimed to 1) develop a method to assess vascular function in fetal mice and 2) as a proof of principle ascertain whether a high dose of sildenafil citrate (SC; Viagra) administered to the pregnant dam affected fetal vascular reactivity. We developed a wire myography methodology for evaluation of fetal vascular function in vitro using the placenta-specific insulin-like growth factor II (Igf2) knockout mouse (P0; a model of FGR). Vascular function was determined in abdominal aortas isolated from P0 and wild-type (WT) fetuses at embryonic day (E) 18.5 of gestation. A subset of dams received SC 0.8 mg/ml via drinking water from E12.5; data were compared with water-only controls. Using wire myography, we found that fetal aortic rings exhibited significant agonist-induced contraction, and endothelium-dependent and endothelium-independent relaxation. Sex-specific alterations in reactivity were noted in both strains. Maternal treatment with SC significantly attenuated endothelium-dependent and endothelium-independent relaxation of fetal aortic rings. Mouse fetal abdominal aortas reproducibly respond to vasoactive agents. Study of these vessels in mouse genetic models of pregnancy complications may 1) help to delineate early signs of abnormal vascular reactivity and 2) inform whether treatments given to the mother during pregnancy may impact upon fetal vascular function., (Copyright © 2014 the American Physiological Society.)

Epidemiological observations report an association between intrauterine growth restriction (IUGR) and cardiovascular diseases. Systemic maternal inflammation is the most common stress during pregnancy, leading to IUGR. We hypothesized that perinatal inflammation and hyperoxygenation induce discernible alterations in cardiomyocyte contractility and calcium signaling, causing early cardiac dysfunction. Pregnant C3H/HeN mice were injected with LPS or saline on embryonic day 16. Newborn mice were placed in 85% O2 or room air (RA) for 14 days. Pups born to LPS-injected dams had reduced birth weight. Echocardiographic measurements revealed that in vivo LV function was compromised in LPS/O2 mice as early as 3 days of life. Isolated cardiomyocytes from LPS/O2 mice at day 14 exhibited decreased sarcomere fractional shortening, along with decreased time-to-90% peak shortening. Calcium transient amplitude was greatest in LPS/O2 mice. SERCA2a mRNA and protein levels were increased and phospholamban mRNA levels were decreased in LPS/O2 mice. Phosphorylation of phospholamban was increased, along with Sorcin mRNA levels in LPS/O2 mice. Combined exposure to perinatal inflammation and hyperoxia resulted in growth restriction, in vivo and in vitro cardiac dysfunction, coinciding with humans and animal models of cardiac dysfunction. Expression of calcium handling proteins during the neonatal period was similar to that observed during fetal stages of development. Our data suggest that perinatal inflammation and hyperoxia exposure alter fetal development, resulting in early cardiac dysfunction.

Intrauterine growth restriction (IUGR) and pregnancy hypertensive disorders such as preeclampsia (PE) associated with IUGR share a common placental phenotype called "placental insufficiency", originating in early gestation when high availability of energy is required. Here, we assess mitochondrial content and the expression and activity of respiratory chain complexes (RCC) in placental cells of these pathologies. We measured mitochondrial (mt)DNA and nuclear respiratory factor 1 (NRF1) expression in placental tissue and cytotrophoblast cells, gene and protein expressions of RCC (real-time PCR and Western blotting) and their oxygen consumption, using the innovative technique of high-resolution respirometry. We analyzed eight IUGR, six PE, and eight uncomplicated human pregnancies delivered by elective cesarean section. We found lower mRNA levels of complex II, III, and IV in IUGR cytotrophoblast cells but no differences at the protein level, suggesting a posttranscriptional compensatory regulation. mtDNA was increased in IUGR placentas. Both mtDNA and NRF1 expression were instead significantly lower in their isolated cytotrophoblast cells. Finally, cytotrophoblast RCC activity was significantly increased in placentas of IUGR fetuses. No significant differences were found in PE placentas. This study provides genuine new data into the complex physiology of placental oxygenation in IUGR fetuses. The higher mitochondrial content in IUGR placental tissue is reversed in cytotrophoblast cells, which instead present higher mitochondrial functionality. This suggests different mitochondrial content and activity depending on the placental cell lineage. Increased placental oxygen consumption might represent a limiting step in fetal growth restriction, preventing adequate oxygen delivery to the fetus.

Intrauterine growth restriction (IUGR) is a fetal complication of pregnancy epidemiologically linked to cardiovascular disease in the newborn later in life. However, the mechanism is poorly understood with very little research on the vascular structure and function during development in healthy and IUGR neonates. Previously, we found vascular remodeling and increased stiffness in the carotid and umbilical arteries, but here we examine the remodeling and biomechanics in the larger vessels more proximal to the heart. To study this question, thoracic and abdominal aortas were collected from a sheep model of placental insufficiency IUGR (PI-IUGR) due to exposure to elevated ambient temperatures. Aortas from control (n = 12) and PI-IUGR fetuses (n = 10) were analyzed for functional biomechanics and structural remodeling. PI-IUGR aortas had a significant increase in stiffness (P < 0.05), increased collagen content (P < 0.05), and decreased sulfated glycosaminoglycan content (P < 0.05). Our derived constitutive model from experimental data related increased stiffness to reorganization changes of increased alignment angle of collagen fibers and increased elastin (P < 0.05) in the thoracic aorta and increased concentration of collagen fibers in the abdominal aorta toward the circumferential direction verified through use of histological techniques. This fetal vascular remodeling in PI-IUGR may set the stage for possible altered growth and development and help to explain the pathophysiology of adult cardiovascular disease in previously IUGR individuals.

Intrauterine growth restriction (IUGR) affects 7-10% of pregnancies and is associated with cardiovascular remodeling and dysfunction, which persists into adulthood. The underlying subcellular remodeling and cardiovascular programming events are still poorly documented. Cardiac muscle is central in the fetal adaptive mechanism to IUGR given its high energetic demands. The energetic homeostasis depends on the correct interaction of several molecular pathways and the adequate arrangement of intracellular energetic units (ICEUs), where mitochondria interact with the contractile machinery and the main cardiac ATPases to enable a quick and efficient energy transfer. We studied subcellular cardiac adaptations to IUGR in an experimental rabbit model. We evaluated the ultrastructure of ICEUs with transmission electron microscopy and observed an altered spatial arrangement in IUGR, with significant increases in cytosolic space between mitochondria and myofilaments. A global decrease of mitochondrial density was also observed. In addition, we conducted a global gene expression profile by advanced bioinformatics tools to assess the expression of genes involved in the cardiomyocyte energetic metabolism and identified four gene modules with a coordinated over-representation in IUGR: oxygen homeostasis (GO: 0032364), mitochondrial respiratory chain complex I (GO:0005747), oxidative phosphorylation (GO: 0006119), and NADH dehydrogenase activity (GO:0003954). These findings might contribute to changes in energetic homeostasis in IUGR. The potential persistence and role of these changes in long-term cardiovascular programming deserves further investigation.

This study tested the hypothesis that Rho kinase contributes to the enhanced pressor response to acute angiotensin II in intact male growth-restricted and gonadectomized female growth-restricted rats. Mean arterial pressure (MAP) and renal function were determined in conscious animals pretreated with enalapril (250 mg/l in drinking water) for 1 wk to block the endogenous renin-angiotensin system and normalize blood pressure (baseline). Blood pressure and renal hemodynamics did not differ at baseline. Acute Ang II (100 ng·kg(-1)·min(-1)) induced a greater increase in MAP and renal vascular resistance and enhanced reduction in glomerular filtration rate in intact male growth-restricted rats compared with intact male controls (P < 0.05). Cotreatment with the Rho kinase inhibitor fasudil (33 μg·kg(-1)·min(-1)) significantly attenuated these hemodynamic changes (P < 0.05), but it did not abolish the differential increase in blood pressure above baseline, suggesting that the impact of intrauterine growth restriction on blood pressure in intact male growth-restricted rats is independent of Rho kinase. Gonadectomy in conjunction with fasudil returned blood pressure back to baseline in male growth-restricted rats, and yet glomerular filtration rate remained significantly reduced (P < 0.05). Thus, these data suggest a role for enhanced renal sensitivity to acute Ang II in the developmental programming of hypertension in male growth-restricted rats. However, inhibition of Rho kinase had no effect on the basal or enhanced increase in blood pressure induced by acute Ang II in the gonadectomized female growth-restricted rat. Therefore, these studies suggest that Rho kinase inhibition exerts a sex-specific effect on blood pressure sensitivity to acute Ang II in growth-restricted rats.

In pregnancy complicated by placental insufficiency (PI) and intrauterine growth restriction (IUGR), the fetus near term has reduced basal and glucose-stimulated insulin concentrations and reduced β-cell mass. To determine whether suppression of insulin concentrations and β-cell mass precedes reductions in fetal weight, which would implicate insulin deficiency as a cause of subsequent IUGR, we measured basal and glucose-stimulated insulin concentrations and pancreatic histology at 0.7 gestation in PI fetuses. Placental weights in the PI pregnancies were 40% lower than controls (265 ± 26 vs. 442 ± 41 g, P < 0.05), but fetal weights were not different. At basal conditions blood oxygen content, plasma glucose concentrations, and plasma insulin concentrations were lower in PI fetuses compared with controls (2.5 ± 0.3 vs. 3.5 ± 0.3 mmol/l oxygen, P < 0.05; 1.11 ± 0.09 vs. 1.44 ± 0.12 mmol/l glucose; 0.12 ± 0.01 vs. 0.27 ± 0.02 ng/ml insulin; P < 0.05). During a steady-state hyperglycemic clamp (~2.5 ± 0.1 mmol/l), glucose-stimulated insulin concentrations were lower in PI fetuses than controls (0.28 ± 0.02 vs. 0.55 ± 0.04 ng/ml; P < 0.01). Plasma norepinephrine concentrations were 3.3-fold higher (P < 0.05) in PI fetuses (635 ± 104 vs. 191 ± 91 pg/ml). Histological examination revealed less insulin area and lower β-cell mass and rates of mitosis. The pancreatic parenchyma was also less dense (P < 0.01) in PI fetuses, but no differences were found for pancreatic progenitor cells or other endocrine cell types. These findings show that hypoglycemia, hypoxemia, and hypercatecholaminemia are present and potentially contribute to lower insulin concentrations and β-cell mass due to slower proliferation rates in early third-trimester PI fetuses before discernible reductions in fetal weight.