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Increased uterine artery blood flow in hypoxic murine pregnancy is not sufficient to prevent fetal growth restriction†.

ABSTRACT: Incomplete maternal vascular responses to pregnancy contribute to pregnancy complications including intrauterine growth restriction (IUGR) and preeclampsia. We aimed to characterize maternal vascular dysfunction in a murine model of fetal growth restriction as an approach toward identifying targetable pathways for improving pregnancy outcomes. We utilized a murine model of late-gestation hypoxia-induced IUGR that reduced E18.5 fetal weight by 34%. Contrary to our hypothesis, uterine artery blood flow as measured in vivo by Doppler ultrasound was increased in mice housed under hypobaric hypoxia (385 mmHg; 5500 m) vs normoxia (760 mmHg; 0 m). Using wire myography, uterine arteries isolated from hypoxic mice had similar vasodilator responses to the two activators A769662 and acetylcholine as those from normoxic mice, although the contribution of an increase in nitric oxide production to uterine artery vasodilation was reduced in the hypoxic vs normoxic groups. Vasoconstrictor responses to phenylephrine and potassium chloride were unaltered by hypoxia. The levels of activated adenosine monophosphate-activated protein kinase (AMPK) were reduced with hypoxia in both the uterine artery and placenta as measured by western blot and immunohistochemistry. We concluded that the rise in uterine artery blood flow may be compensatory to hypoxia but was not sufficient to prevent fetal growth restriction. Although AMPK signaling was reduced by hypoxia, AMPK was still receptive to pharmacologic activation in the uterine arteries in which it was a potent vasodilator. Thus, AMPK activation may represent a new therapy for pregnancy complications involving reduced uteroplacental perfusion.

SUBMITTER: Lane SL

PROVIDER: S-EPMC7068112 | biostudies-literature | 2020 Mar

REPOSITORIES: biostudies-literature

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Increased uterine artery blood flow in hypoxic murine pregnancy is not sufficient to prevent fetal growth restriction†.

Lane Sydney L SL Doyle Alexandrea S AS Bales Elise S ES Lorca Ramón A RA Julian Colleen G CG Moore Lorna G LG

Biology of reproduction 20200301 3

Incomplete maternal vascular responses to pregnancy contribute to pregnancy complications including intrauterine growth restriction (IUGR) and preeclampsia. We aimed to characterize maternal vascular dysfunction in a murine model of fetal growth restriction as an approach toward identifying targetable pathways for improving pregnancy outcomes. We utilized a murine model of late-gestation hypoxia-induced IUGR that reduced E18.5 fetal weight by 34%. Contrary to our hypothesis, uterine artery blood ...[more]

PMID: 31711123

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Project description:Key pointsPregnancy at high altitude is associated with a greater incidence of fetal growth restriction due, in part, to lesser uterine artery blood flow. AMP-activated protein kinase (AMPK) activation vasodilates arteries and may increase uterine artery blood flow. In this study, pharmacological activation of AMPK by the drug AICAR improved fetal growth and elevated uterine artery blood flow. These results suggest that AMPK activation is a potential strategy for improving fetal growth and raising uterine artery blood flow in pregnancy, which may be important in pregnancy disorders characterized by uteroplacental ischaemia and/or fetal hypoxia.AbstractUteroplacental hypoxia is associated with pregnancy disorders such as intrauterine growth restriction and preeclampsia, which are characterized by uteroplacental ischaemia and/or fetal hypoxia. Activation of AMP-activated protein kinase (AMPK) results in vasodilatation and is therefore a potential therapeutic strategy for restoring uteroplacental perfusion in pregnancy disorders. In this study, C57Bl/6 mice were treated with subcutaneous pellets containing vehicle, the AMPK activator AICAR (200 mg kg-1 day-1 ), or the AMPK inhibitor Compound C (20 mg kg-1 day-1 ) beginning on gestational day 13.5, and were exposed to hypoxia starting on gestational day 14.5 that induced intrauterine growth restriction. Pharmacological AMPK activation by AICAR partially prevented hypoxia-induced fetal growth restriction (P < 0.01), due in part to increased uterine artery blood flow (P < 0.0001). The proportion of total cardiac output flowing through the uterine artery was increased with AICAR in hypoxic mice (P < 0.001), suggesting that the vasodilator effect of AICAR was selective for the uterine circulation. Further, pharmacological inhibition of AMPK with Compound C reduced uterine artery diameter and increased uterine artery contractility in normoxic mice, providing evidence that physiological levels of AMPK activation are necessary for vasodilatation in healthy pregnancy. Two-way ANOVA analyses indicated that hypoxia reduced AMPK activation in the uterine artery and placenta, and AICAR increased AMPK activation in these tissues compared to vehicle. These findings provide support for further investigation into the utility of pharmacological AMPK activation for treatment of fetal growth restriction.

Project description:IntroductionEarly-onset fetal growth restriction is a pregnancy complication often coinciding with abnormal Doppler flow in the umbilical artery. Absent or reversed end-diastolic flow in the umbilical artery is associated with adverse perinatal outcome. As the optimal management of this condition is unclear, the objective of this study was to analyze the time interval from admission to delivery of pregnancies with early-onset fetal growth restriction, while pursuing a policy of postponing delivery unless active management of labor would be required because of fetal distress or maternal condition. We also assessed short- and long-term perinatal outcome.Material and methodsIn this historical cohort study, all pregnant women with singleton pregnancies, admitted during 2004-2015 with early-onset fetal growth restriction were included. Pregnancies with absent or reversed end-diastolic flow (AREDF) were compared with pregnancies with a positive end-diastolic Doppler flow (PEDF). Time until delivery was determined and perinatal outcome was assessed for both groups.ResultsIn our study, 111 women were allocated to the PEDF group and 109 to the AREDF group. In the AREDF group, fetal distress was more often an indication for delivery, in comparison with the PEDF group (p = .004). Median time until delivery in patients admitted between 26 and 28 weeks' gestation was 6+5 weeks in the PEDF group and 1+4 weeks in the AREDF group (p = .001). No statistically significant difference was found between the Doppler groups in the composite adverse neonatal outcome, which includes at least one of the following outcomes: infant respiratory distress syndrome, sepsis, bronchopulmonary dysplasia, necrotizing enterocolitis, intraventricular hemorrhage >grade 2, periventricular leukomalacia and perinatal death (p = .63).ConclusionsIn this study, comprising pregnancies with early-onset fetal growth restriction, fetal distress was observed more frequently in the AREDF group with the consequence of delivery at an earlier stage of gestation, compared with the PEDF group. AREDF was not associated with increased perinatal morbidity and mortality compared with PEDF.

Project description:ObjectiveTo describe the short- and long-term outcomes of infants with early-onset fetal growth restriction (FGR) and umbilical artery absent or reversed end-diastolic flow (AREDF), delivered before 30 weeks' gestation and managed proactively.MethodsThis was a retrospective cohort study of fetuses delivered for fetal indication before 30 completed weeks' gestation that had early-onset FGR (defined as estimated fetal weight more than 2 SD below the mean) with AREDF in the umbilical artery (FGR group), at the level-3 perinatal unit in Lund, Sweden, between 1998 and 2015. Perinatal outcome and neurodevelopment at ≥ 2 years of age in surviving infants were compared with those of a group of infants without small-for-gestational-age birth weight or any known fetal Doppler changes delivered before 30 weeks in Lund during the corresponding time period (non-FGR group). In the FGR group, the main indication for delivery was the Doppler finding of AREDF in the umbilical artery.ResultsThere were 139 fetuses (of which 26% were a twin/triplet) in the FGR group and 946 fetuses (of which 28% were a twin/triplet) in the non-FGR group. The FGR infants had a median birth weight of 630 g (range, 340-1165 g) and gestational age at birth of 187 days (range, 164-209 days), as compared with 950 g (range, 470-2194 g) and 185 days (range, 154-209 days), respectively, in the non-FGR group. The rate of fetal mortality did not differ between the two groups (5.0% and 5.4% in the FGR and non-FGR groups, respectively). All seven intrauterine deaths in the FGR group occurred before 26 weeks' gestation. In the FGR group compared with the non-FGR group, severe intraventricular hemorrhage was less frequent and bronchopulmonary dysplasia and septicemia were more frequent (P = 0.008, P < 0.001 and P = 0.017, respectively). In the FGR group, the survival rate at 2 years (83% of liveborn infants) and the rate of cerebral palsy (7%) did not differ significantly from those in the non-FGR group (82% and 8%, respectively). The rate of survival without neurodevelopmental impairment was higher in the non-FGR group (83%) than in the FGR group (62%) (P < 0.001), as well as in infants in the FGR group delivered at or after 26 weeks (72%) compared with those delivered before 26 weeks (40%) (P = 0.003). Within the FGR group, outcomes were similar between twins and singletons and, in those who survived beyond 2 years, outcomes were similar between fetuses with absent and those with reversed end-diastolic flow in the umbilical artery.ConclusionsInfants delivered very preterm after severe FGR with AREDF in the umbilical artery had a similar rate of survival as did non-FGR infants of corresponding gestational age; however, they were at higher risk of neurodevelopmental impairment, the risk being most pronounced following birth before 26 weeks. Gestational age remains an important factor associated with the prognosis of early-onset FGR; nevertheless, the present results support the hypothesis, which should be tested prospectively, that fetuses with early-onset FGR and umbilical artery AREDF may benefit from early intervention rather than expectant management, and that umbilical artery Doppler findings could be incorporated into clinical protocols for cases very early in gestation. © 2020 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

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Increased uterine artery blood flow in hypoxic murine pregnancy is not sufficient to prevent fetal growth restriction†.

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Increased uterine artery blood flow in hypoxic murine pregnancy is not sufficient to prevent fetal growth restriction†.

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