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Effects of spaceflight and simulated weightlessness on longitudinal bone growthIndirect measurements have suggested that spaceflight impairs bone elongation in rats. To test this possibility, our laboratory measured, by the fluorochrome labeling technique, bone elongation that occurred during a spaceflight experiment. The longitudinal growth rate (LGR) in the tibia of rats in spaceflight experiments (Physiological Space Experiments 1, 3, and 4 and Physiological-Anatomical Rodent Experiment 3) and in two models of skeletal unloading (hind-limb elevation and unilateral sciatic neurotomy) were calculated. The effects of an 11 day spaceflight on gene expression of cartilage matrix proteins in rat growth plates were also determined by northern analysis and are reported for the first time in this study. Measurements of longitudinal growth indicate that skeletal unloading generally did not affect LGR, regardless of age, strain, gender, duration of unloading, or method of unloading. There was, however, one exception with 34% suppression in LGR detected in slow-growing, ovariectomized rats skeletally unloaded for 8 days by hind-limb elevation. This detection of reduced LGR by hind-limb elevation is consistent with changes in steady-state mRNA levels for type II collagen (-33%) and for aggrecan (-53%) that were detected in rats unloaded by an 11 day spaceflight. The changes detected in gene expression raise concern that spaceflight may result in changes in the composition of extracellular matrix, which could have a negative impact on conversion of growth-plate cartilage into normal cancellous bone by endochondral ossification.
Document ID
20040112715
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Sibonga, J. D.
(Mayo Clinic Rochester, MN 55905, United States)
Zhang, M.
Evans, G. L.
Westerlind, K. C.
Cavolina, J. M.
Morey-Holton, E.
Turner, R. T.
Date Acquired
August 21, 2013
Publication Date
October 1, 2000
Publication Information
Publication: Bone
Volume: 27
Issue: 4
ISSN: 8756-3282
Subject Category
Aerospace Medicine
Distribution Limits
Public
Copyright
Other
Keywords
manned
STS-62 Shuttle Project
Flight Experiment
NASA Discipline Regulatory Physiology
STS-57 Shuttle Project
STS-41 Shuttle Project
NASA Experiment Number DC85LS04
Non-NASA Center
NASA Experiment Number CPPSE01
short duration
STS-56 Shuttle Project

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