Document Detail

Adaptation of diaphyseal structure to aging and decreased mechanical loading in the adult rat: a densitometric and histomorphometric study.
MedLine Citation:
PMID:  2024773     Owner:  NLM     Status:  MEDLINE    
Nine-month-old female rats were subjected to right hindlimb immobilization or served as controls for 0, 2, 10, 18, and 26 weeks. They were double-labeled with bone markers prior to sacrifice. Experimental unloading was produced by immobilizing the right limb against the abdomen with an elastic bandage. Single-photon absorptiometry was performed on the intact femurs; static and dynamic histomorphometry were performed on 20-micron thick toluidine blue-stained, undecalcified cross sections of the tibial shafts. Changes in the continuously immobilized tibiae were compared to those in both tibiae of age-matched controls. Unloading shut off nearly all periosteal bone formation and accelerates bone marrow expansion over that which occurs in age-related controls. The effect of unloading appeared to be mediated by recruiting fewer osteoblasts which showed inhibited activity. Furthermore, unloading increased endocortical percentage eroded surface. These histological changes lowered cortical bone mass by inhibiting diaphyseal cross sectional expansion and enlarging the bone marrow cavity. The results support Frost's suggestion that decrease mechanical usage depresses bone modeling-dependent bone gain by decreasing activation of modeling in the formation mode. It also stimulates bone remodeling-dependent bone loss by increasing activation of remodeling in the resorption mode.
X J Li; W S Jee
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The Anatomical record     Volume:  229     ISSN:  0003-276X     ISO Abbreviation:  Anat. Rec.     Publication Date:  1991 Mar 
Date Detail:
Created Date:  1991-05-31     Completed Date:  1991-05-31     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0370540     Medline TA:  Anat Rec     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  291-7     Citation Subset:  IM; S    
Division of Radiobiology, University of Utah, Salt Lake City 84112.
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MeSH Terms
Absorptiometry, Photon
Adaptation, Physiological / physiology*
Aging / physiology*
Bone Density / physiology
Bone Marrow / anatomy & histology
Bone and Bones / anatomy & histology,  physiology*
Immobilization / physiology
Rats, Inbred Strains
Stress, Mechanical
Grant Support

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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