Abstract:

BACKGROUND: Reports demonstrated that a transient stretch can cause different degree of spinal cord injury. The effect of persistent stretch on myeloid tissues remains unclear. 
OBJECTIVE: To observe the effect of mild persistent stretch on expression of superoxide dismutase (SOD) and malonaldehyde (MDA) of rabbits. 
METHODS: Totally 36 healthy, white, rabbits were randomly divided into 3 groups: rabbits in the sham-operated group only install internal fixation; those in the experimental group were stretched 25% of transverse diameter of L1/L2 articular surface and fixed by internal fixation; those in the control group were housed at the same conditions. At 3, 7 and 14 days after intervention, function of spinal cord was assessed, levels of MDA and SOD in spinal cord tissues were determined. 
RESULTS AND CONCLUSION: A total of 36 rabbits were included in the final analysis. The motor functions of rabbits were slightly decreased in the experimental and sham-surgery groups after operation, which began recovery at 7 days and return to normal levels at 14 days after operation. There was no significance between two groups in decline of motion function at the same time period. From 8 days after operation, the motion function of animals had no significant difference compared with before operation. The SOD activity decreased but MDA contents increased in spinal cord tissues. The neuronal interspaces increased at 3 days, Nissl's body reduce, and some neuronatrophy, no other pathological changes could be found in the experimental group. No abnormality could be seen in the other groups.