Please use this identifier to cite or link to this item: http://hdl.handle.net/2440/7920
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Type: Journal article
Title: Intravenous infusion of insulin-like growth factor I in fetal sheep reduces hepatic IGF-I and IGF-II mRNAs
Author: Kind, K.
Owens, J.
Lok, F.
Robinson, J.
Quinn, K.
Mundy, L.
Gilmour, R.
Owens, P.
Citation: American Journal of Physiology. Regulatory Integrative and Comparative Physiology, 1996; 271(6):R1632-R1637
Publisher: American Physiological Society
Issue Date: 1996
ISSN: 0002-9513
1522-1490
Statement of
Responsibility: 
Karen L. Kind, Julie A. Owens, Fong, Lok, Jeffrey S. Robinson, Kirsty J. Quinn, Linda Mundy, R. Stewart Gilmour, and Phillip C. Owens
Abstract: Liver contains the highest concentrations of insulin-like growth factor (IGF) I mRNA in adult rats and sheep and is a major source of circulating IGF-I. In rats, inhibition of hepatic IGF-I production by exogenous IGF-I has been reported. In fetal sheep, skeletal muscle and liver are major sites of IGF-I synthesis and potential sources of circulating IGF-I. To determine whether feedback inhibition of IGF gene expression in fetal liver or muscle by IGF-I occurs, IGF-I and IGF-II mRNAs were measured in these tissues after intravenous infusion of recombinant human IGF-I into fetal sheep. Infusion of IGF-I (26 +/- 4 micrograms.h-1.kg-1; n = 6) or saline (n = 6) commenced on day 120 of pregnancy (term = 150 days) and continued for 10 days. Plasma concentrations of IGF-I were threefold higher in infused fetuses at 130 days of gestation (P < 0.0003), whereas those of IGF-II were unchanged. IGF-I infusion reduced the relative abundance of IGF-I mRNA (P < 0.0002) and IGF-II mRNA (P < 0.01) in fetal liver by approximately 50% but did not alter IGF-I or IGF-II mRNA in skeletal muscle. These results indicate that IGF-I inhibits the expression of both IGF-I and IGF-II genes in fetal liver and that IGF gene expression in fetal liver and muscle is differentially regulated by IGF-I.
Keywords: Liver; Fetal Blood; Fetus; Animals; Sheep; Humans; Insulin; Blood Glucose; Insulin-Like Growth Factor I; Insulin-Like Growth Factor II; Insulin-Like Growth Factor Binding Proteins; Recombinant Proteins; RNA, Messenger; Blotting, Western; Infusions, Intravenous; Female
Rights: Copyright © 1996 the American Physiological Society
RMID: 0030005348
DOI: 10.1152/ajpregu.1996.271.6.r1632
Published version: http://ajpregu.physiology.org/content/271/6/R1632
Appears in Collections:Obstetrics and Gynaecology publications

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