The Establishment Of Improved Model Of Rat Tail Intervertebral Disc Degeneration

Objective:①Rat caudal immobilized vertebrae were changed in order to avoid the nutritional effects of intervertebral disc degeneration.②Improved intervertebral disc degeneration model of rat caudal was established.Methods:PartⅠ:24 mature (4-month-old retired breeders) female Sprague-Dawley rats were divided into control and experimental groups. The apparatus was applied to the 7th and 10th caudal vertebrae of experimental group and the control group was not installed. Kirschner wire is perpendicular to the tail and leaving it with 45°angle of the sagittal. Intramuscular injection of penicillin and alcohol were used to prevent infection after surgery.4 rats each were randomly selected specimens of two groups at 1,2,3 months after surgery were taken the MRI examination and measured MEANS value. Purpose of intervertebral disc tissue was removed after the imaging examination and then examined pathologically.PartⅡ:This part was basically the same with the first part. The apparatus was applied to the 7th and 10th caudal vertebrae of two groups. But it was compressed 3N of experimental group and the control group was not.Results:PartⅠ:The vertebral space of two groups were normal at 3 months after surgery. The signal of control group nucleus pulposus in T2 imaging did not change significantly. The signal of experimental group Co7～8 and Co9～10 nucleus pulposus in T2 imaging decreased with time increase and Co8～9 no significant changing. The MEANS value of Co7～8 and Co9～10 nucleus pulposus of experimental group compared with the control group decreased. There was significant statistically between the MEANS value of control group and experimental group at 3 month after surgery. The MEANS value of Co8～9 nucleus pulposus of experimental group at 3 months slightly decreased, but no statistical significance between two group. The nucleus pulposus in the control group had more uniform arrangement of notochord cells and chondroid cells and annulus layers arranged in neat rows. The Co7～8 and Co9～10 nucleus pulposus cells of experimental group reduced at 3 months after surgery and Co8～9 was normal. The collagen of typeⅠand typeⅡwere more regular mesh in the nucleus pulposus of control group. The collagen of typeⅠwas deep in the Co7～8 and Co9～10 nucleus pulposus of experimental group and Co8～9 was normal. The collagen of typeⅡhad not significant difference at 3 months after surgery.PartⅡ:The vertebral space of experimental group was narrowing at 3 months after surgery. The signal of nucleus pulposus in T2 imaging significantly decreased and the boundary between endplate and nucleus pulposus were blurred. The MEANS value of experimental group and the control group were statistically significant. The nucleus pulposus cells of experimental group significantly reduced at 3 months after surgery and necrotic cells appeared. Annulus was obvious swelling and irregular arrangement. The transition region was narrowing between annulus and nucleus. Collagen typeⅠof nucleus pulposus in the experimental group showed depth staining than the control group and collagen typeⅡshowed shallow. The network structure was damaged. The control group did not change significantly.Conclusion:①Four adjacent caudal vertebraes were fixed with the external fixation apparatus and needle direction was changed in order to avoid the nutritional effects of intervertebral disc degeneration. In this study, the influence of nutritional disorder to disc degeneration had been resolved.②Intervertebral disc degeneration animal models had been successfully used to establish modified methods. The satisfactory experimental platform had been provided to the study of intervertebral disc degeneration. This method of developing the animal experiment offers model to study the degeneration of lumbar intervertebra disc.