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Regional responsiveness of the tibia to intermittent administration of parathyroid hormone as affected by skeletal unloadingTo determine whether the acute inhibition of bone formation and deficit in bone mineral induced by skeletal unloading can be prevented, we studied the effects of intermittent parathyroid hormone (PTH) administration (8 micrograms/100 g/day) on growing rats submitted to 8 days of skeletal unloading. Loss of weight bearing decreased periosteal bone formation by 34 and 51% at the tibiofibular junction and tibial midshaft, respectively, and reduced the normal gain in tibial mass by 35%. Treatment with PTH of normally loaded and unloaded animals increased mRNA for osteocalcin (+58 and +148%, respectively), cancellous bone volume in the proximal tibia (+41 and +42%, respectively), and bone formation at the tibiofibular junction (+27 and +27%, respectively). Formation was also stimulated at the midshaft in unloaded (+47%, p < 0.05), but not loaded animals (-3%, NS). Although cancellous bone volume was preserved in PTH-treated, unloaded animals, PTH did not restore periosteal bone formation to normal nor prevent the deficit in overall tibial mass induced by unloading. We conclude that the effects of PTH on bone formation are region specific and load dependent. PTH can prevent the decrease in cancellous bone volume and reduce the decrement in cortical bone formation induced by loss of weight bearing.
Document ID
20040172942
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Halloran, B. P.
(University of California San Francisco, United States)
Bikle, D. D.
Harris, J.
Tanner, S.
Curren, T.
Morey-Holton, E.
Date Acquired
August 22, 2013
Publication Date
July 1, 1997
Publication Information
Publication: Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research
Volume: 12
Issue: 7
ISSN: 0884-0431
Subject Category
Aerospace Medicine
Distribution Limits
Public
Copyright
Other
Keywords
NASA Center ARC
Non-NASA Center
NASA Discipline Musculoskeletal

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