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Type: Journal article
Title: Insulin-like growth factor-I promotes growth selectively in fetal sheep in late gestation
Author: Lok, F.
Owens, J.
Mundy, L.
Robinson, J.
Owens, P.
Citation: American Journal of Physiology, 1996; 270(5):R1148-R1155
Publisher: American Physiological Society
Issue Date: 1996
ISSN: 0002-9513
Statement of
Fong Lok, Julie A. Owens, Linda Mundy, Jeffrey S. Robinson, and Phillip C. Owens
Abstract: Insulin-like growth factor I (IGF-I) is required for normal fetal growth and skeletal maturation in late gestation, because null mutations of the IGF-I gene in mice reduce fetal weight and retard ossification of bones. To determine if, conversely, increased abundance of IGF-I promotes fetal growth and skeletal maturation, fetal sheep were infused intravascularly with recombinant human IGF-I (n = 7) (26 +/- 3 micrograms. from 120 to 130 days gestation and compared with controls (n = 15). IGF-I infusion increased plasma IGF-I concentrations by 140% (P = 0.002) and weights of fetal liver, lungs, heart, kidneys, spleen, pituitary, and adrenal glands by 16-50% (P < 0.05). Weights and/or lengths of the fetus, placenta, gastrointestinal tract, individual skeletal muscles, and long bones were unchanged by IGF-I. However, IGF-I increased the percentage of proximal epiphyses of long bones present (P < 0.05) and their cross-sectional areas by 15 to 38% (P < 0.05). These results show that IGF-I promotes growth of major fetal organs, endocrine glands, and skeletal maturation in vivo, consistent with IGF-I actively controlling and not merely facilitating fetal growth. The variable response of different tissues may partly reflect tissue specificity in growth requirements for additional factors.
Keywords: Musculoskeletal System
Fetal Blood
Insulin-Like Growth Factor I
Insulin-Like Growth Factor II
Recombinant Proteins
Embryonic and Fetal Development
Bone Development
Rights: Copyright © 1996 the American Physiological Society
DOI: 10.1152/ajpregu.1996.270.5.r1148
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