+Gz重复暴露对兔颈椎间盘退行性改变的影响

Effects of Repeated + Gz Exposures on Cervical Intervertebral Disc in Rabbits

目的探讨不同时间的+Gz暴露对兔颈椎间盘的影响。方法 15只兔随机分为对照组、+Gz暴露1d组、2周组、4周组、6周组,每组3只。+Gz暴露组分别暴露于+6Gz、持续45s的+Gz(每天连续5次)1d、2周、4周及6周。各组动物均于实验前后颈椎侧位拍片作自身对比,实验结束后气栓法处死并取颈椎C_3～C_7段显微镜下观察。结果 1)X光片显示对照组、+Gz暴露1d组及2周组兔颈椎无明显变化,而+Gz暴露4周组和6周组兔颈椎较对照组均出现显著退行性改变(P<0.01)；2)显微镜下显示+Gz暴露2周组、4周组及6周组兔颈椎间盘均出现纤维排列轻度不规则,其中6周组兔颈椎间盘还出现髓棱缩小及软骨细胞增生。结论 +6Gz重复暴露4周和6周可引起兔颈椎间盘出现退行性改变。

Objective To explore the cumulative effect of exposure to ＋ Gz on intervertebral disc in rabbits. Method Fifteen rabbits were randomly divided into control group, ＋6 Gz/1 d group, ＋6 Gz/ 2 weeks group, ＋6 Gz/4 weeks group and ＋ 6 Gz/6 weeks group. The rabbits in groups except control group were exposed to ＋6 Gz/45 s（5 times every day） for 1 d, 2 weeks, 4 weeks and 6 weeks respectively. Lateral Cervical Radiographs of each rabbit before and after exposure were studied. Pathological changes of the cervical vertebrae were observed under light microscope after staining with hematoxylin and eosin. Result 1）As compared with control, the X-ray films revealed that there were no changes of cervical vertebra in the rabbits suffered to 1 d and 2 weeks of ＋6 Gz exposures, while significant degenerative changes of intervertebral discs were observed in rabbits suffered to 4 weeks and 6 weeks of ＋6 Gz exposures （P 〈0.01 ） ;2） Fissure and irregular arrangement were found in fibrous ring of intervertebral disc by histological examination in rabbits of 2 weeks, 4 weeks and 6 weeks of ＋6 Gz exposures. Shrinking of nucleus pulposus and proliferation of cartilage cells occurred in rabbits suffered to 6 weeks of ＋6 Gz exposures. Conclusion Repeated ＋6 Gz exposures for 4 weeks and 6 weeks may induce degeneration of intervertebral disc in rabbits.