Arctic ground squirrels limit bone loss during the prolonged physical inactivity associated with hibernation

Samantha J. Wojda, Richard A. Gridley, Meghan Elizabeth McGee Lawrence, Thomas D. Drummer, Ann Hess, Franziska Kohl, Brian M. Barnes, Seth W. Donahue

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Prolonged disuse (e.g., physical inactivity) typically results in increased bone porosity, decreased mineral density, and decreased bone strength, leading to increased fracture risk in many mammals. However, bears, marmots, and two species of ground squirrels have been shown to preserve macrostructural bone properties and bone strength during long seasons of hibernation while they remain mostly inactive. Some small hibernators (e.g., 13-lined ground squirrels) show microstructural bone loss (i.e., osteocytic osteolysis) during hibernation, which is not seen in larger hibernators (e.g., bears and marmots). Arctic ground squirrels (Urocitellus parryii) are intermediate in size between 13-lined ground squirrels and marmots and are perhaps the most extreme rodent hibernator, hibernating for up to 8 mo annually with body temperatures below freezing. The goal of this study was to quantify the effects of hibernation and inactivity on cortical and trabecular bone properties in arctic ground squirrels. Cortical bone geometrical properties (i.e., thickness, cross-sectional area,and moment of inertia) at themidshaft of the femur were not different in animals sampled over the hibernation and active seasons. Femoral ultimate stress tended to be lower in hibernators than in summer animals, but toughness was not affected by hibernation. The area of osteocyte lacunae was not different between active and hibernating animals. There was an increase in osteocytic lacunar porosity in the hibernation group due to increased lacunar density. Trabecular bone volume fraction in the proximal tibia was unexpectedly greater in the hibernation group than in the active group. This study shows that, similar to other hibernators, arctic ground squirrels are able to preserve many bone properties during hibernation despite being physically inactive for up to 8 mo.

Original languageEnglish (US)
Pages (from-to)72-80
Number of pages9
JournalPhysiological and Biochemical Zoology
Volume89
Issue number1
DOIs
StatePublished - Jan 1 2016

Fingerprint

Hibernation
Sciuridae
squirrels
hibernation
Arctic region
Bone
bones
Bone and Bones
Marmota
bone strength
Porosity
Animals
porosity
preserves
Osteocytes
animals
Osteolysis
Mammals
thighs
Thigh

Keywords

  • Arctic ground squirrels
  • Bone mechanics
  • Disuse osteoporosis
  • Hibernation

ASJC Scopus subject areas

  • Physiology
  • Biochemistry
  • Animal Science and Zoology

Cite this

Arctic ground squirrels limit bone loss during the prolonged physical inactivity associated with hibernation. / Wojda, Samantha J.; Gridley, Richard A.; McGee Lawrence, Meghan Elizabeth; Drummer, Thomas D.; Hess, Ann; Kohl, Franziska; Barnes, Brian M.; Donahue, Seth W.

In: Physiological and Biochemical Zoology, Vol. 89, No. 1, 01.01.2016, p. 72-80.

Research output: Contribution to journalArticle

Wojda, Samantha J. ; Gridley, Richard A. ; McGee Lawrence, Meghan Elizabeth ; Drummer, Thomas D. ; Hess, Ann ; Kohl, Franziska ; Barnes, Brian M. ; Donahue, Seth W. / Arctic ground squirrels limit bone loss during the prolonged physical inactivity associated with hibernation. In: Physiological and Biochemical Zoology. 2016 ; Vol. 89, No. 1. pp. 72-80.
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