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

ObjectiveTo 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.MethodsThirty-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 quantitated by image analysis.ResultsIn 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).ConclusionAfter 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.