Physical exercise during remobilization restores a normal bone trabecular network after tail suspension-induced osteopenia in young rats
- 1 May 1995
- journal article
- research article
- Published by Oxford University Press (OUP) in Journal of Bone and Mineral Research
- Vol. 10 (5) , 820-828
- https://doi.org/10.1002/jbmr.5650100520
Abstract
To determine how bone recovers from immobilization‐induced bone loss and to specify whether its recovering capacity is improved by physical exercise, 5‐week‐old male Wistar rats (287.07 g ± 10.65 SD) were tail suspended for 14 days, then returned to either normal weight‐bearing (R) or controlled physical exercise for 28 days (R + E). Bone mineral density (BMD) was measured in three parts of the femur. Using histomorphometric analysis, bone mass and architecture were estimated in the primary (1°sp) and secondary spongiosa (2°sp) of the proximal tibial metaphysis. Bone cellular parameters were measured in the 2°sp of the tibia. Tail suspension induced a significant decrease in BMD, 2°sp bone mass, mineral apposition rate, and bone formation rate and marked alterations of the trabecular network. In R rats, BMD was still significantly decreased, except in the distal part of the femur. Long‐bone lengthening was significantly altered. The 2°sp bone mass returned to the age‐matched control values; however, the trabeculae were still significantly thinner and bone resorption was significantly higher. R + E rats had a normal long bone lengthening and a significant increase in 2°sp bone mass and trabecular thickness when compared with R rats. Bone resorption was significantly depressed, and osteoid surfaces and thickness were significantly increased. Thus, although bone mass returns to normal values in the R group, trabecular alterations persist. Physical exercise during recovery helps restore a normal trabecular network, and the depressed bone resorption associated with an increased bone formation leads to an increased bone volume.Keywords
Funding Information
- Direction des Recherches et Etudes Techniques (90/079)
- French Ministry of Defence
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