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Insulin-like growth factor I promotes growth selectively in fetal sheep in late gestation
journal contribution
posted on 1996-05-01, 00:00 authored by F Lok, Julie OwensJulie Owens, L Mundy, J S Robinson, P C OwensInsulin-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. h-1.kg-1) 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.
History
Journal
American journal of physiologyVolume
270Issue
5Pagination
R1148 - R1155Publisher
American Physiological SocietyLocation
Bethesda, Md.Publisher DOI
ISSN
0002-9513Language
engPublication classification
C1.1 Refereed article in a scholarly journalCopyright notice
1996, American Physiological SocietyUsage metrics
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No categories selectedKeywords
AnimalsBone DevelopmentEmbryonic and Fetal DevelopmentFemaleFetal BloodFetusHumansInsulinInsulin-Like Growth Factor IInsulin-Like Growth Factor IIMusculoskeletal SystemPlacentaPregnancyRecombinant ProteinsSheepScience & TechnologyLife Sciences & BiomedicinePhysiologyendocrine glandsboneossificationMESSENGER RIBONUCLEIC-ACIDSBINDING-PROTEINSRECEPTOR GENEHUMAN-FETUSHORMONERATEXPRESSIONHYPOPHYSECTOMYCHONDROCYTESLAMB
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