The Expression And Significance Of MMP-3 In Lumbar Intervertebral Disc Of The Tail-suspended Rats

Objective: 1. To investigate the feasibility of establishing a rat model of lumber intervertebral disc degeneration by suspending the tail.2. To detect the expression of matrix metalloproteinases-3 in the tail-suspended rat model of intervertebral disc degeneration, and explore the role of matrix metalloproteinases-3 in mechanism of disc degeneration, to supply theoretical support for the etiology and treatment of the degenerative disc disease.Methods: Thirty six SD (Sprague-Dawley) rats were randomly divided into two groups: control group (A group) and tail-suspended group (B group),each group had 18 SD rats. Tail-suspended rats were suspended with the method improved by Chen Jie et al. Each rat was kept in separate cage tail suspended, front legs could touch the ground, hind legs were dangling, the body axis to the horizontal nearly 30°, was free to get food and water. The rat of the control group was kept in the normal breeding cages. At the end of 2 weeks, 4 weeks, 8 weeks, six rats were randomly selected from normal control group and experimental group and were anesthetized for imaging (X-ray and MRI). The lumbar intervertebral disc tissue was took away after the rats were sacrificed for histopathological and immuno- histochemical analyses.Results: X-ray examination (CR) displayed that lumbar intervertebral spaces became narrower in tail-suspended group, upper and lower cartilage endplates were calcified, and vertebral bodies were deformity and unstability. There was no significant change in the lumbar vertebrae of the normal control group. MRI showed that the signal of nucleus pulposus in tail-suspended group in T2 decreased,and no significant change in the control group. It was obserbved in histopathologicay that cells in nucleus pulposus were recuced,and peripheral annulus fibrosis-like changed in tail-suspended group. Immunohistochemistry showed that matrix metalloproteinases-3 showed a positive expression in both the normal control group and the tail suspension group, but the expression of matrix metalloproteinases-3 in the tail-suspended group was higher than the normal control group, the difference was statistically significant (P <0.05).Conclusions: 1. The tail suspended method was successfully established an animal model of lumbar disc degeneration. Tail suspension is a reliable, noninvasive, and reproducible method of lumber intervertebral disc degeneration. 2. The expression of matrix metalloproteinases-3 increased in degenerative lumbar disc tissue. It indicated that there is a close relationship between matrix metalloproteinases-3 and lumbar degenerative disc.