Effect of electroacupuncture on pain threshold and spinal NR2B subunit expression in a rat model of neuropathic pain

Objective To observe the effect of electroacupuncture (EA) on pain threshold and spinal NR2B subunit expression in a rat model of neuropathic pain due to chronic compression injury (CCI) of the sciatic nerve and explore the analgesic mechanism of EA. Methods Male SD rats weighing 200-280 g were randomly divided into 4 groups (n=10),namely the sham-operated group,CCI group,EA+CCI group,and sham EA+CCI group. All the rats underwent tests of the mechanical withdrawal threshold and thermal threshold. On day 13 after the surgery,all the rats were decapitated to collect the L4-6 segments of the spinal cord to examine NR2B expression using Western blotting. Results The postoperative mechanical withdrawal threshold and thermal threshold were significantly lowered in CCI,EA+CCI and sham EA+CCI groups as compared to those before the surgery (P0.05). EA obviously alleviated the hypersensitivity in the rats with CCI and inhibited spinal NR2B expressions (P0.05). No significant differences were found in the mechanical withdrawal threshold,thermal threshold or spinal NR2B subunit expression between CCI group and sham EA+CCI group (P0.05). Conclusion EA may alleviate neuropathic hypersensitivity partially by inhibiting NR2B expression in the spinal cord of rats with neuropathic pain resulting from CCI of the sciatic nerve.