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https://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, 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 |
DOI: | 10.1152/ajpregu.1996.271.6.r1632 |
Published version: | http://ajpregu.physiology.org/content/271/6/R1632 |
Appears in Collections: | Aurora harvest 4 Obstetrics and Gynaecology publications |
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