Abstract: Objective To observe the dynamic expression of Nogo receptor (NgR) in spinal cord of rats after spinal cord injury. Methods 108 Sprague-Dawley rats were randomly assigned into normal group, sham operated group and model group, with 36 rats in each group. The model of spinal cord injury was established with the modified Allen's method. The rats were killed 24 h, 3 days, 7 days and 14 days respectively after intervention (9 rats from each group), and expression of NgR in the spinal cord tissue of the rats was detected with immunohistochemistry and Western blotting, and expression of NgR mRNA was detected with fluorescence quantitative PCR. Results There was no significant change in the expression of NgR in the normal group and the sham operated group (P>0.05). The expression of protein and mRNA of NgR was less in the model group 24 h after modeling, dropped to the lowest on the 3rd day, then rapidly peaked on the 7th day, and gradually declined on the 14th day after spinal cord injury. Compared with the normal group, there were significant differences in expression of NgR in immunohistochemistry and Western blotting in the model group at each time point after spinal cord injury (P<0.05). Compared with the sham operated group, there were significant differences in expression of NgR mRNA in the model group at each time point after spinal cord injury (P<0.01). Conclusion The expression of NgR and mRNA peaks on the 7th day after spinal cord injury in the rats, and maintains at high level for a long time, which may associated with the difficulty of axonal regeneration after spinal cord injury.

Key words: spinal cord injury, Nogo receptor, axonal regeneration, rats