An experimental study of bone loss after spinal cord injury and immobilization in rats

English Keywords:Spinal cord injury  Osteoporosis  Femur  Bone density  Osteoclast

English Abstract:

  【Abstract】 Objective：To establish rats models with both spinal cord injury（SCI） and lower limbs disused atrophy，and to observe the bone density and number of osteoclast at distal femur.Method：A total of 24 male rats of 7 weeks were randomly divided into three groups：control group（group A），the SCI group（group B） and the immobilization group（group C）.After general anesthesia，T10 vertebrae laminar was removed in group B and A，while weight-drop（60g·cm）　on spinal cords（Allen′s contusion SCI model）　was introduced only in group B；rats in group C were immobilized by bilateral hindlimbs-tail fixation.The Basso，Beattie，Bresnahan（BBB）　scale was used to evaluate the injury severity by rating hindlimb functional deficits on day 1 and 7 post-injury.Animals were sacrificed on day 10 post-injury for subsequent analyses.Bone density of elbow-bone，radius and femur at one side was measured.The TRAP staining was performed on the distal femur of the other side to detect the number of osteoclast.Result：Ｂone density in the distal femur ｏｆ　ｇｒｏｕｐ　Ａ，Ｂ，Ｃ　was　０．１１４，０．０９６，０．１０８ｇ／ｃｍ２．Ｔｈｅ　ｄｉｆｆｅｒｅｎｃｅ　ｏｆ　ｔｈｅｍ　ｗａｓ　ｓｉｇｎｉｆｉｃａｎｔ（P<0.05）.No difference of bone density in the elbow-bone and radius between three groups was noted（P＞0.05）.Compared with group A，the number of osteoclast at the distal femora in group B increased most，the less was in group C and A（P<0.01）　respectively.Conclusion：SCI results in a rapid bone loss in early stage which is originated from increasing number and potential of osteoclast，which is more serious than disused bone loss.