Expression of NF-κB in Schwann cells and its effect on motor neuron apoptosis in spinal cord following sciatic nerves injury in rats

Objective: To explore the expression of nuclear factor-kappa B (NF-κB) in Schwann cells (SCs) and its effect on motor neuron apoptosis in spinal cord following sciatic nerves injury in adult rats. Methods: Thirty-six adult Sprague-Dawley (SD) rats were divided randomly into normal control group (n=6), and sciatic nerves crushing group (n=30). and the later was further equally randomized into 5 subgroups: 1. 3. 7. 11. and 21 d post-injury groups. The expression of NF-κB of normal and injured nerves were examined by immunohistochemistry staining, and the apoptosis of motor neurons in spinal cord of lumbar 4 to lumbar 6 (L4-L6) was investigated by terminal deoxynucleotidyl transferase mediated dUTP-biotin nick end labeling (TUNED assay. Both were quantitated by image analysis. Results: In crushing group, except 21 d post-injury group, the expression of NF-κB was markedly higher than that in the normal control group (P<0. 05,P<0. 01). At 1 d after sciatic nerves crushing, the expression of NF-κB was obviously up-regulated, reached peak at 3 d. and recovered at 21 d. The same trend was observed in the time-course on motor neuron apoptosis after sciatic nerves injury. Correlation analyses revealed that motor neuron apoptosis was significantly and positively correlated with the expression of NF-κB following sciatic nerves injury (r=0. 976 0,P<0. 01). Conclusion: After injury of sciatic nerves, the presence and up-regulation of NF-κB in SCs may be involved in motor neuron apoptosis in L4-L6 spinal cord.

Objective：To explore the expression of nuclear factor-kappa B （NF-kB） in Schwann cells （SCs） and its effect on motor neuron apoptosis in spinal cord following sciatic nerves injury in adult rats. Methods： Thirty-six adult Sprague-Dawley （SD） rats were divided randomly into normal control group （n=6）, and sciatic nerves crushing group （n= 30）, and the later was further equally randomized into 5 subgroups： 1, 3, 7, 14, and 21 d post-injury groups. The expression of NF-kB of normal and injured nerves were examined by immunohistochemistry staining, and the apoptosis of motor neurons in spinal cord of lumbar 4 to lumbar 6 （L4-L6） was investigated by terminal deoxynucleotidyl transferase mediated dUTP-biotin nick end labeling （TUNEL） assay. Both were qua.ntitated by image analysis. Results： In crushing group, except 21 d post-injury group, the expression of NF-kB was markedly higher than that in the normal control group （P〈0.05, P〈0. 01）. At 1 d after sciatic nerves crushing, the expression of NF-kB was obviously up-regulated, reached peak at 3 d, and recovered at 21 d. The same trend was observed in the time-course on motor neuron apoptosis after sciatic nerves injury. Correlation analyses revealed that motor neuron apoptosis was significantly and positively correlated with the expression of NF-kB following sciatic nerves injury （r= 0. 976 0, P〈0. 01）. Conclusion： After injury of sciatic nerves, the presence and up-regulation of NF-kB in SCs may be involved in motor neuron apoptosis in L4-L6 spinal cord.