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Altered skeletal pattern of gene expression in response to spaceflight and hindlimb elevationSpaceflight leads to osteopenia, in part by inhibiting bone formation. Using an animal model (hindlimb elevation) that simulates the weightlessness of spaceflight, we and others showed a reversible inhibition of bone formation and bone mineralization. In this study, we have measured the mRNA levels of insulin-like growth factor I (IGF-I), IGF-I receptor (IGF-IR), alkaline phosphatase, and osteocalcin in the tibiae of rats flown aboard National Aeronautics and Space Administration Shuttle Flight STS-54 and compared the results with those obtained from their ground-based controls and from the bones of hindlimb-elevated animals. Spaceflight and hindlimb elevation transiently increase the mRNA levels for IGF-I, IGF-IR, and alkaline phosphatase but decrease the mRNA levels for osteocalcin. The changes in osteocalcin and alkaline phosphatase mRNA levels are consistent with a shift toward decreased maturation, whereas the rise in IGF-I and IGF-IR mRNA levels may indicate a compensatory response to the fall in bone formation. We conclude that skeletal unloading during spaceflight or hindlimb elevation resets the pattern of gene expression in the osteoblast, giving it a less mature profile.
Document ID
20050000281
Acquisition Source
Ames Research Center
Document Type
Reprint (Version printed in journal)
Authors
Bikle, D. D.
(University of California San Francisco)
Harris, J.
Halloran, B. P.
Morey-Holton, E.
Date Acquired
August 22, 2013
Publication Date
December 1, 1994
Publication Information
Publication: The American journal of physiology
Volume: 267
Issue: 6 Pt 1
ISSN: 0002-9513
Subject Category
Aerospace Medicine
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Musculoskeletal
Flight Experiment
STS-54 Shuttle Project
Non-NASA Center
short duration
NASA Center ARC
manned

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