Effects of repeated +GZ exposure on cervical intervertebral disc in rabbits

Background This study was to explore the cumulative effect of exposure to +Gz on intervertebral disc in rabbits. Method 25 rabbits were randomly divided into 5 groups: control, +6Gz/1d, +6Gz/2wk, +6Gz/4wk and +6Gz/6wk group. Lateral Cervical Radiographies of each rabbit were studied with self-control method. Pathological changes of the cervical vertebrae were observed by light microscope after staining with hematoxylin-eosin. Results The X-ray films revealed that there were no changes of cervical vertebrae in rabbits of control, +6Gz/1d and 2wks group, while significant degenerative changes of intervertebral discs were observed in rabbits suffered to 4wks and 6wks of +6Gz exposure(P<0.01). Fissure and irregular arrangement were found in fibrous ring of intervertebral disc by histological examination in rabbits of 2wks, 4wks and 6wks of +6Gz exposure. Shrinking of nucleus pulposus and proliferation of cartilage cells occurred in rabbits suffered to 6 wks of +6Gz exposure. Conclusion Repeated +6Gz exposure for 4wks and 6wks may induce degeneration of intervertebral disc in rabbits.