Document Detail

Thirteen-lined ground squirrels (Ictidomys tridecemlineatus) show microstructural bone loss during hibernation but preserve bone macrostructural geometry and strength.
MedLine Citation:
PMID:  21430199     Owner:  NLM     Status:  MEDLINE    
Lack of activity causes bone loss In most animals. Hibernating bears have physiological processes to prevent cortical and trabecular bone loss associated with reduced physical activity, but different mechanisms of torpor among hibernating species may lead to differences in skeletal responses to hibernation. There are conflicting reports regarding whether small mammals experience bone loss during hibernation. To investigate this phenomenon, we measured cortical and trabecular bone properties in physically active and hibernating juvenile and adult 13-lined ground squirrels (Ictidomys tridecemlineatus, previous genus name Spermophilus). Cortical bone geometry, strength and mineral content were similar in hibernating compared with active squirrels, suggesting that hibernation did not cause macrostructural cortical bone loss. Osteocyte lacunar size increased (linear regression, P=0.001) over the course of hibernation in juvenile squirrels, which may indicate an osteocytic role in mineral homeostasis during hibernation. Osteocyte lacunar density and porosity were greater (+44 and +59%, respectively; P<0.0001) in hibernating compared with active squirrels, which may reflect a decrease in osteoblastic activity (per cell) during hibernation. Trabecular bone volume fraction in the proximal tibia was decreased (-20%; P=0.028) in hibernating compared with physically active adult squirrels, but was not different between hibernating and active juvenile squirrels. Taken together, these data suggest that 13-lined ground squirrels may be unable to prevent microstructural losses of cortical and trabecular bone during hibernation, but importantly may possess a biological mechanism to preserve cortical bone macrostructure and strength during hibernation, thus preventing an increased risk of bone fracture during remobilization in the spring.
Meghan E McGee-Lawrence; Danielle M Stoll; Emily R Mantila; Bryna K Fahrner; Hannah V Carey; Seth W Donahue
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of experimental biology     Volume:  214     ISSN:  1477-9145     ISO Abbreviation:  J. Exp. Biol.     Publication Date:  2011 Apr 
Date Detail:
Created Date:  2011-03-24     Completed Date:  2011-07-14     Revised Date:  2013-06-30    
Medline Journal Info:
Nlm Unique ID:  0243705     Medline TA:  J Exp Biol     Country:  England    
Other Details:
Languages:  eng     Pagination:  1240-7     Citation Subset:  IM    
Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
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MeSH Terms
Bone Density
Bone and Bones / anatomy & histology*,  chemistry,  pathology*,  physiology
Hibernation / physiology*
Sciuridae / anatomy & histology*,  physiology*
Stress, Mechanical
Grant Support

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