scholarly journals Increased Hepatic Glucose Production in Fetal Sheep With Intrauterine Growth Restriction Is Not Suppressed by Insulin

Diabetes ◽  
2012 ◽  
Vol 62 (1) ◽  
pp. 65-73 ◽  
Author(s):  
Stephanie R. Thorn ◽  
Laura D. Brown ◽  
Paul J. Rozance ◽  
William W. Hay ◽  
Jacob E. Friedman
Keyword(s):  
Intrauterine Growth Restriction ◽  
Hepatic Glucose Production ◽  
Glucose Production ◽  
Growth Restriction ◽  
Fetal Sheep ◽  
Intrauterine Growth ◽  
Hepatic Glucose

scholarly journals Coordinated changes in hepatic amino acid metabolism and endocrine signals support hepatic glucose production during fetal hypoglycemia

2015 ◽  
Vol 308 (4) ◽  
pp. E306-E314 ◽  
Author(s):  
Satya S. Houin ◽  
Paul J. Rozance ◽  
Laura D. Brown ◽  
William W. Hay ◽  
Randall B. Wilkening ◽  
...  
Keyword(s):  
Fetal Liver ◽  
Hepatic Glucose Production ◽  
Plasma Concentrations ◽  
Glucose Production ◽  
Late Gestation ◽  
Fetal Sheep ◽  
Fetal Plasma ◽  
Hepatic Glucose ◽  
Molar Percent ◽  
Glucose Output

Reduced fetal glucose supply, induced experimentally or as a result of placental insufficiency, produces an early activation of fetal glucose production. The mechanisms and substrates used to fuel this increased glucose production rate remain unknown. We hypothesized that in response to hypoglycemia, induced experimentally with maternal insulin infusion, the fetal liver would increase uptake of lactate and amino acids (AA), which would combine with hormonal signals to support hepatic glucose production. To test this hypothesis, metabolic studies were done in six late gestation fetal sheep to measure hepatic glucose and substrate flux before (basal) and after [days (d)1 and 4] the start of hypoglycemia. Maternal and fetal glucose concentrations decreased by 50% on d1 and d4 ( P < 0.05). The liver transitioned from net glucose uptake (basal, 5.1 ± 1.5 μmol/min) to output by d4 (2.8 ± 1.4 μmol/min; P < 0.05 vs. basal). The [U-13C]glucose tracer molar percent excess ratio across the liver decreased over the same period (basal: 0.98 ± 0.01, vs. d4: 0.89 ± 0.01, P < 0.05). Total hepatic AA uptake, but not lactate or pyruvate uptake, increased by threefold on d1 ( P < 0.05) and remained elevated throughout the study. This AA uptake was driven largely by decreased glutamate output and increased glycine uptake. Fetal plasma concentrations of insulin were 50% lower, while cortisol and glucagon concentrations increased 56 and 86% during hypoglycemia ( P < 0.05 for basal vs. d4). Thus increased hepatic AA uptake, rather than pyruvate or lactate uptake, and decreased fetal plasma insulin and increased cortisol and glucagon concentrations occur simultaneously with increased fetal hepatic glucose output in response to fetal hypoglycemia.

scholarly journals Intrauterine growth restriction decreases NF-κB signaling in fetal pulmonary artery endothelial cells of fetal sheep

2018 ◽  
Vol 315 (3) ◽  
pp. L348-L359 ◽  
Author(s):  
R. Blair Dodson ◽  
Kyle N. Powers ◽  
Jason Gien ◽  
Paul J. Rozance ◽  
Gregory Seedorf ◽  
...  
Keyword(s):  
Pulmonary Artery ◽  
Intrauterine Growth Restriction ◽  
Lung Diseases ◽  
Growth Restriction ◽  
Mouse Lung ◽  
Similar Degree ◽  
Fetal Sheep ◽  
Vascular Growth ◽  
Intrauterine Growth ◽  
Pulmonary Artery Endothelial Cell

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.

scholarly journals Differential effects of intrauterine growth restriction and a hypersinsulinemic-isoglycemic clamp on metabolic pathways and insulin action in the fetal liver

2019 ◽  
Vol 316 (5) ◽  
pp. R427-R440 ◽  
Author(s):  
Amanda K. Jones ◽  
Laura D. Brown ◽  
Paul J. Rozance ◽  
Natalie J. Serkova ◽  
William W. Hay ◽  
...  
Keyword(s):  
Amino Acid ◽  
Signaling Pathways ◽  
Cholesterol Synthesis ◽  
Fetal Liver ◽  
Energy State ◽  
Hepatic Glucose Production ◽  
Glucose Production ◽  
Fetal Sheep ◽  
Intrauterine Growth ◽  
Insulin Clamp

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 1H-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.

scholarly journals Exogenous amino acids suppress glucose oxidation and potentiate hepatic glucose production in late gestation fetal sheep

2017 ◽  
Vol 312 (5) ◽  
pp. R654-R663 ◽  
Author(s):  
Laura D. Brown ◽  
Jaden R. Kohn ◽  
Paul J. Rozance ◽  
William W. Hay ◽  
Stephanie R. Wesolowski
Keyword(s):  
Glucose Oxidation ◽  
Hepatic Glucose Production ◽  
Glucose Production ◽  
Late Gestation ◽  
Fetal Sheep ◽  
Oxidation Rates ◽  
Carbon Supply ◽  
Hepatic Glucose ◽  
Arterial Plasma ◽  
Branched Chain

Acute amino acid (AA) infusion increases AA oxidation rates in normal late gestation fetal sheep. Because the fetal oxygen consumption rate does not change with increased AA oxidation, we hypothesized that AA infusion would suppress glucose oxidation pathways and that the additional carbon supply from AA would activate hepatic glucose production. To test this, late gestation fetal sheep were infused intravenously for 3 h with saline or exogenous AA (AA). Glucose tracer metabolic studies were performed and skeletal muscle and liver tissues samples were collected. AA infusion increased fetal arterial plasma branched chain AA, cortisol, and glucagon concentrations. Fetal glucose utilization rates were similar between basal and AA periods, yet the fraction of glucose oxidized and the glucose oxidation rate were decreased by 40% in the AA period. AA infusion increased expression of PDK4, an inhibitor of glucose oxidation, nearly twofold in muscle and liver. In liver, AA infusion tended to increase PCK1 gluconeogenic gene and PCK1 correlated with plasma cortisol concentrations. AA infusion also increased liver mRNA expression of the lactate transporter gene ( MCT1), protein expression of GLUT2 and LDHA, and phosphorylation of AMPK, 4EBP1, and S6 proteins. In isolated fetal hepatocytes, AA supplementation increased glucose production and PCK1, LDHA, and MCT1 gene expression. These results demonstrate that AA infusion into fetal sheep competitively suppresses glucose oxidation and potentiates hepatic glucose production. These metabolic patterns support flexibility in fetal metabolism in response to increased nutrient substrate supply while maintaining a relatively stable rate of oxidative metabolism.

scholarly journals Chronic anemic hypoxemia increases plasma glucagon and hepatic PCK1 mRNA in late-gestation fetal sheep

2016 ◽  
Vol 311 (1) ◽  
pp. R200-R208 ◽  
Author(s):  
Christine Culpepper ◽  
Stephanie R. Wesolowski ◽  
Joshua Benjamin ◽  
Jennifer L. Bruce ◽  
Laura D. Brown ◽  
...  
Keyword(s):  
Mrna Expression ◽  
Hepatic Glucose Production ◽  
Glucose Production ◽  
Late Gestation ◽  
Hepatic Glycogen ◽  
Plasma Glucagon ◽  
Low Oxygen ◽  
Fetal Sheep ◽  
Hepatic Glucose ◽  
Arterial Plasma

Hepatic glucose production (HGP) normally begins just prior to birth. Prolonged fetal hypoglycemia, intrauterine growth restriction, and acute hypoxemia produce an early activation of fetal HGP. To test the hypothesis that prolonged hypoxemia increases factors which regulate HGP, studies were performed in fetuses that were bled to anemic conditions (anemic: n = 11) for 8.9 ± 0.4 days and compared with control fetuses ( n = 7). Fetal arterial hematocrit and oxygen content were 32% and 50% lower, respectively, in anemic vs. controls ( P < 0.005). Arterial plasma glucose was 15% higher in the anemic group ( P < 0.05). Hepatic mRNA expression of phosphonenolpyruvate carboxykinase ( PCK1) was twofold higher in the anemic group ( P < 0.05). Arterial plasma glucagon concentrations were 70% higher in anemic fetuses compared with controls ( P < 0.05), and they were positively associated with hepatic PCK1 mRNA expression ( P < 0.05). Arterial plasma cortisol concentrations increased 90% in the anemic fetuses ( P < 0.05), but fetal cortisol concentrations were not correlated with hepatic PCK1 mRNA expression. Hepatic glycogen content was 30% lower in anemic vs. control fetuses ( P < 0.05) and was inversely correlated with fetal arterial plasma glucagon concentrations. In isolated primary fetal sheep hepatocytes, incubation in low oxygen (3%) increased PCK1 mRNA threefold compared with incubation in normal oxygen (21%). Together, these results demonstrate that glucagon and PCK1 may potentiate fetal HGP during chronic fetal anemic hypoxemia.

Effects of intrauterine growth restriction on lung liquid dynamics and lung development in fetal sheep

2001 ◽  
Vol 184 (2) ◽  
pp. 209-216 ◽  
Author(s):  
Megan L. Cock ◽  
Cheryl A. Albuquerque ◽  
Belinda J. Joyce ◽  
Stuart B. Hooper ◽  
Richard Harding
Keyword(s):  
Intrauterine Growth Restriction ◽  
Lung Development ◽  
Growth Restriction ◽  
Fetal Sheep ◽  
Intrauterine Growth ◽  
Lung Liquid ◽  
Liquid Dynamics

Increased Stiffness of the Abdominal Aorta With Intrauterine Growth Restriction in the Near-Term Fetal Sheep

2012 ◽  
Author(s):  
Reuben Blair Dodson ◽  
Paul J. Rozance ◽  
Kendall S. Hunter ◽  
Virginia L. Ferguson
Keyword(s):  
Abdominal Aorta ◽  
Intrauterine Growth Restriction ◽  
Structural Changes ◽  
Epidemiological Studies ◽  
Growth Restriction ◽  
Fetal Sheep ◽  
Intrauterine Growth ◽  
Systemic Artery ◽  
Artery Stiffness ◽  
Near Term

Fetal intrauterine growth restriction (IUGR) results in increased placental resistance to blood flow, fetal hypertension and increased pulsatility [1]. These hemodynamic changes have been shown to lead to vascular remodeling in adolescents and adults [2, 3] but have received little study of its effect during this critical period of vascular formation. Epidemiological studies link IUGR to cardiovascular disease in adulthood [4], but the reason for this is not clearly understood. Here, we examine a large elastic artery for developmental alterations under hypertensive conditions. We hypothesize that fetal hypertension induces abdominal aorta (AA) stiffening in the fetal ovine model of IUGR and that the increased systemic artery stiffness is due to altered extracellular matrix (ECM) composition and structural changes.

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