Effects Of Different Exercises On Bone Metabolism In Rats After Suspension

Objective: To investigate the effects of long-term different exercise(endurance exercise,resistance exercise and endurance + resistance exercise)on bone metabolism in rats after suspension and its possible mechanism.Methods: 56 male rats of 8 weeks old were randomly divided into control group(group C,n=16)and suspension group(group T,n=40).After 2 weeks of suspension of the T group by the suspension system(TSS),the C group was randomly divided into the blank control group 1(C1 group)and the blank control group 2(C2 group),and the T group was randomly divided into two groups immediately after suspension.Group(T1 group),post-suspension control group(TC group),endurance exercise group(TA group),resistance exercise group(TR group)and endurance + resistance exercise group(TAR group),8 rats in each group.MircoCT was used to detect bone mineral density in rats in C1 and T1 groups.ELISA was used to detect calcitonin(CT),parathyroid hormone(PTH),osteoprotegerin(OPG),nuclear factor kappa B receptor activating factor ligand(RANKL),7 blood biochemical indicators such as alkaline phosphatase(ALP),tartrate-resistant acid phosphatase(TRAP),collagen pyridine cross-linking peptide(ICTP).The TC group did not exercise,and the TA,TR,and TAR groups underwent 4 weeks of endurance exercise,resistance exercise,endurance + resistance exercise training,and the above indicators were detected after exercise.RESULTS:(1)After two weeks of suspension,the bone density of the T1 group was significantly lower than that of the C1 group;the CT and TRAP values were significantly increased;the OPG,ALP and OPG/RANKL ratios were significantly decreased.Compared with the T1 group and the C2 group,it was found that after 4 weeks of natural recovery,the bone density of the TC group increased,but it did not return to the normal level,and the changes of various biochemical indicators showed a recovery trend,but no significant difference was observed.(2)After 4 weeks of exercise intervention,compared with the TC group,the bone mineral density of each exercise group increased,and the bone density of the TR group was the most significant,and the bone density of the TR group was significantly higher than that of the TAR group.The CT value of the TR group was significantly decreased,the OPG/RANKL ratio was increased,the osteoblast marker protein ALP was increased,and the osteoclast marker proteins TRAP and ICTP were decreased.Compared with the C2 group,the bone mineral density and biochemical indicators of the exercise group were not seen.Significant difference;compared with TAR group,TR group had higher CT value,there was significant difference;TR group ALP index was higher than TA group and TAR group,there was significant difference;compared with TR group,TA group increased ICTP index There are significant differences.Conclusion:(1)After 2 weeks of suspension,the bone mineral density of the rats decreased significantly,the CT value of biochemical markers related to bone metabolism increased significantly,and the OPG/RANKL ratio decreased significantly.(2)Static recovery after suspension can not effectively improve the biochemical index disorder and bone density decline caused by suspension in rats.(3)Different movements around the four weeks can effectively improve the bone density reduction and related biochemical indexes caused by suspension,and the best resistance to exercise,endurance exercise and endurance plus resistance exercise.Exercise improves bone metabolism disorder and may stimulate CT with exercise,which promotes the involvement of OPG\RANKL system in regulating bone metabolism and promoting osteogenesis.