[Expression of NF-kappaB and TNF-alpha in spinal dorsal horn in a rat model of neuropathic pain].

OBJECTIVE: To investigate the expressions of NF-kappaB and TNF-alpha in lumbar spinal cord in a rat model of chronic constrictive injury (CCI). METHODS: Seventy-six male SD rats were randomly divided into 2 groups (n = 38 each): CCI group receiving chronic constriction injury and sham group receiving sham operation as control. The mechanical and thermal nociceptive thresholds were assessed with paw withdrawal latency (PWL) to von Frey filaments and radiant heat at different time points. Five animals were sacrificed at each time point for real-time polymerase chain reaction (real-time PCR) and another three animals sacrificed at 7 d post-operation for double-immunofluorescence histochemical staining. Lumbar segments of spinal cord were removed. The expressions of NF-kappaB and TNF-alpha in spinal cord were examined by real-time PCR and double-immunofluorescence histochemical technique. RESULTS: The post-operative thresholds to mechanical and thermal stimuli decreased obviously. As compared with contralateral side and sham group, the expressions of NF-kappaB and TNF-alpha mRNA increased significantly in ipsilateral spinal dorsal horn. Their expressions began to increase at 4 d post-operation and peaked at 7 d. Then TNF-alpha began to decrease while NF-kappaB maintained at a high level throughout the experiment. Double-immunofluorescence histochemical staining revealed extensive co-localization of NF-kappaB with TNF-alpha on ipsilateral side of dorsal horn. CONCLUSION: The activation of NF-kappaB and its downstream inflammatory mediators may be involved in the regulation of neuropathic pain.