Sustained hypoxemia in late gestation potentiates hepatic gluconeogenic gene expression but does not activate glucose production in the ovine fetus

Amanda K. Jones, Paul J. Rozance, Laura D. Brown, David A. Goldstrohm, William W. Hay, Sean W Limesand, Stephanie R. Wesolowski

Research output: Contribution to journalArticle

Abstract

Fetal hypoxemia is associated with pregnancy conditions that cause an early activation of fetal glucose production. However, the independent role of hypoxemia to activate this pathway is not well understood. We hypothesized that fetal hypoxemia would activate fetal glucose production by decreasing umbilical glucose uptake and increasing counter-regulatory hormone concentrations. We induced hypoxemia for 9 days with maternal tracheal N2 gas insufflation to reduce maternal and fetal arterial Po2 by ~20% (HOX) compared with fetuses from ewes receiving intratracheal compressed air (CON). At 0.9 of gestation, fetal metabolic studies were performed (n = 7 CON, 11 HOX). Umbilical blood flow rates, net fetal oxygen and glucose uptake rates, and fetal arterial plasma glucose concentrations were not different between the two groups. Fetal glucose utilization rates were lower in HOX versus CON fetuses but not different from umbilical glucose uptake rates, demonstrating the absence of endogenous glucose production. In liver tissue, mRNA expression of gluconeogenic genes G6PC (P < 0.01) and PCK1 (P = 0.06) were six- and threefold greater in HOX fetuses versus CON fetuses. Increased fetal norepinephrine and cortisol concentrations and hepatic G6PC and PCK1 expression were inversely related to fetal arterial Po2. These findings support a role for fetal hypoxemia to act with counter-regulatory hormones to potentiate fetal hepatic gluconeogenic gene expression. However, in the absence of decreased net fetal glucose uptake rates and plasma glucose concentrations, hypoxemia-induced gluconeogenic gene activation is not sufficient to activate fetal glucose production.

Original languageEnglish (US)
Pages (from-to)E1-E10
JournalAmerican journal of physiology. Endocrinology and metabolism
Volume317
Issue number1
DOIs
StatePublished - Jul 1 2019

Fingerprint

Sheep
Fetus
Gene Expression
Glucose
Pregnancy
Liver
Umbilicus
Hypoxia
Mothers
Hormones
Compressed Air
Insufflation
Transcriptional Activation
Hydrocortisone
Norepinephrine
Gases
Oxygen
Messenger RNA

Keywords

  • fetus
  • glucose
  • hypoxemia
  • liver
  • oxygen

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Physiology
  • Physiology (medical)

Cite this

Sustained hypoxemia in late gestation potentiates hepatic gluconeogenic gene expression but does not activate glucose production in the ovine fetus. / Jones, Amanda K.; Rozance, Paul J.; Brown, Laura D.; Goldstrohm, David A.; Hay, William W.; Limesand, Sean W; Wesolowski, Stephanie R.

In: American journal of physiology. Endocrinology and metabolism, Vol. 317, No. 1, 01.07.2019, p. E1-E10.

Research output: Contribution to journalArticle

Jones, Amanda K. ; Rozance, Paul J. ; Brown, Laura D. ; Goldstrohm, David A. ; Hay, William W. ; Limesand, Sean W ; Wesolowski, Stephanie R. / Sustained hypoxemia in late gestation potentiates hepatic gluconeogenic gene expression but does not activate glucose production in the ovine fetus. In: American journal of physiology. Endocrinology and metabolism. 2019 ; Vol. 317, No. 1. pp. E1-E10.
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AB - Fetal hypoxemia is associated with pregnancy conditions that cause an early activation of fetal glucose production. However, the independent role of hypoxemia to activate this pathway is not well understood. We hypothesized that fetal hypoxemia would activate fetal glucose production by decreasing umbilical glucose uptake and increasing counter-regulatory hormone concentrations. We induced hypoxemia for 9 days with maternal tracheal N2 gas insufflation to reduce maternal and fetal arterial Po2 by ~20% (HOX) compared with fetuses from ewes receiving intratracheal compressed air (CON). At 0.9 of gestation, fetal metabolic studies were performed (n = 7 CON, 11 HOX). Umbilical blood flow rates, net fetal oxygen and glucose uptake rates, and fetal arterial plasma glucose concentrations were not different between the two groups. Fetal glucose utilization rates were lower in HOX versus CON fetuses but not different from umbilical glucose uptake rates, demonstrating the absence of endogenous glucose production. In liver tissue, mRNA expression of gluconeogenic genes G6PC (P < 0.01) and PCK1 (P = 0.06) were six- and threefold greater in HOX fetuses versus CON fetuses. Increased fetal norepinephrine and cortisol concentrations and hepatic G6PC and PCK1 expression were inversely related to fetal arterial Po2. These findings support a role for fetal hypoxemia to act with counter-regulatory hormones to potentiate fetal hepatic gluconeogenic gene expression. However, in the absence of decreased net fetal glucose uptake rates and plasma glucose concentrations, hypoxemia-induced gluconeogenic gene activation is not sufficient to activate fetal glucose production.

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