Effects of intravenous insulin-like growth factor-I and insulin administration on insulin-like growth factor-binding proteins in the ovine fetus

W. H. Shen, X. Yang, David Boyle, W. H. Lee, E. A. Liechty

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

The insulin-like growth factors (IGF) are important anabolic hormones in the mammalian fetus; their anabolic actions are potentially modulated by alterations in the IGF-binding proteins (IGFBP). We have previously shown that the nutritional state of the fetus affects both IGF-I and the IGFBP concentrations. The present study was designed to determine the effect of alterations in insulin and IGF-I circulating concentrations on the IGFBPs. Because both insulin and IGF-I elicit decreases in glucose and amino acid concentrations, the concentrations of these substrates were clamped during the hormone infusions. Sixteen ovine fetuses were chronically catheterized at approximately 115 days of gestation, and experimental procedures performed at approximately 130 days of gestation. Insulin, IGF-I or both were infused for an 8-h period. Baseline concentrations of hormones and binding proteins were obtained, and concentrations were also obtained at the end of the infusion. Hepatic IGFBP-1 mRNA expression was also determined. Intravenous infusion of IGF-I significantly increased IGF-I concentrations in plasma in the ovine fetus. Intravenous infusion of insulin inhibited hepatic IGFBP-1 gene expression when amino acids and glucose were clamped. In contrast, intravenous infusion of recombinant human IGF-I (rhIGF-I) enhanced hepatic IGFBP-1 gene expression. Neither insulin nor rhIGF-I treatment had an effect on hepatic IGFBP-3 gene expression. Insulin did not alter plasma IGFBP-1 significantly, but it increased IGFBP-3 in plasma. rhIGF-I increased both IGFBP-1 and IGFBP-3 protein levels in plasma. The responses of IGFBP-1 and IGFBP-3 to increased plasma IGF-I and insulin may serve to protect the fetus from exaggerated anabolic effects and to blunt the hypoglycemic potential of circulating IGFs and insulin.

Original languageEnglish
Pages (from-to)143-151
Number of pages9
JournalJournal of Endocrinology
Volume171
Issue number1
DOIs
StatePublished - 2001

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Insulin-Like Growth Factor Binding Proteins
Insulin-Like Growth Factor I
Sheep
Fetus
Insulin-Like Growth Factor Binding Protein 1
Insulin
Insulin-Like Growth Factor Binding Protein 3
Intravenous Infusions
Hormones
Gene Expression
Anabolic Agents
Amino Acids
Glucose
Pregnancy
Somatomedins
Hypoglycemic Agents
Blood Proteins
Carrier Proteins

ASJC Scopus subject areas

  • Endocrinology

Cite this

Effects of intravenous insulin-like growth factor-I and insulin administration on insulin-like growth factor-binding proteins in the ovine fetus. / Shen, W. H.; Yang, X.; Boyle, David; Lee, W. H.; Liechty, E. A.

In: Journal of Endocrinology, Vol. 171, No. 1, 2001, p. 143-151.

Research output: Contribution to journalArticle

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