Effects of Exercises on Bone Metabolism and OPG-RANKL-RANK System of Osteoclast Differentiation in Rats with Disuse Osteoporosis / 中国运动医学杂志

ABSTRACT

Objective To explore the effect of treadmill exercises on disuse osteoporosis and the media effect of OPG-RANKL-RANK system of osteoclast differentiation in the process.Methods Forty six-week-old male Sprague-Dawley rats were randomly divided into a normal control group,a disuse model group,a normal recovery group and an exercise recovery group,each of 10.The normal control group were sacrificed 4 weeks later without receiving any special treatment.The disuse model group were sacrificed after 4 weeks of tail suspension.The normal recovery group were sacrificed after 4 weeks of tail suspension and keeping quiet for 4 weeks.The exercise recovery group were sacrificed after 4 weeks of tail suspension and another 4 weeks of treadmill exercises.The indicators of bone mineral density (BMD),bone histomorphometry,bone tissue TRACP-5b staining,bone metabolism and cytokines related to the osteoclast differentiation OPG-RANKL-RANK system were tested immediately after the rats were sacrificed.Results The BMD,trabecular bone volume percentage (TBV),trabecular bone width (Tb.Wi),concentration of serum alkaline phosphatase (ALP) and the gene expression of bone marrow oculopneumoplethysmograph (OPG) of the disuse model goup were significantly lower than those of the normal control group (P＜0.01),while the trabecular bone spacing (Tb.Sp),average positive staining area percentage (APSAP) of tartrate-resistant acid phosphatase (TRACP)-5b,concentration of serum Ca2+ and TRACP-5b and the gene expression of bone marrow cytokines including RANKL,macrophage colony-stinulating factor (M-CSF),RANK,interleukin (IL)-6 and tumor necrosis factor (TNF)-α of the disuse model goup were significantly higher than those of the normal control group (P＜0.01).The BMD,TBV,Tb.Wi,concentration of serum ALP and the gene expression of bone marrow OPG of the exercise recovery group were significantly higher than those of the normal recovery group (P＜0.05 or P＜0.01).The Tb.Sp,APSAP,concentration of serum Ca2+ and TRACP-5b and the gene expression of RANKL,M-CSF,RANK,IL-6 and TNF-α of the exercise recovery group were significantly lower than those of the normal recovery group (P＜0.05 or P＜0.01).Conclusion The 4-week tail suspension can lead to disuse osteoporosis in rats.Treadmill exercise can promote the recovery of rats with the disuse osteoporosis.The occurrence of disuse osteoporosis and the effect of exercises on disuse osteoporosis were related with the expressing of OPG-RANKL-RANK system-related cytokines of osteoclast differentiation in bone marrow microenvironment.