<正>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.