Analgesic effect of COX inhibitors and its mechanism in a rat model of neuropathic pain / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the effect of COX inhibitors on pain threshold and spinal N-methyl-D-aspartate (NMDA) receptor subunit 2B (NR2B) expression in a rat model of neuropathic pain.</p><p><b>METHODS</b>Thirty-six male SD rats were randomly divided into sham-operated group, chronic constriction injury (CCI) of the sciatic nerve group, indomethacin+CCI group, and parecoxib+CCI group with corresponding treatments. All the rats were tested for mechanical withdrawal threshold, and at day 13 after the surgery, the rats were decapitated for detection of NR2B expression in the spinal cord at the L4-6 levels.</p><p><b>RESULTS</b>The mechanical withdrawal threshold were lowered significantly after the operation in CCI, indomethacin+CCI and parecoxib+CCI groups (P<0.05). Parecoxib alleviated the hypersensitivity of CCI model rats but not affected spinal NR2B expressions (P>0.05). No significant differences were found in the mechanical withdrawal threshold or spinal NR2B expression between CCI group and indomethacin+CCI group (P>0.05).</p><p><b>CONCLUSION</b>Parecoxib can alleviate neuropathic hypersensitivity in rats, but this effect may not be associated with NR2B expression in the spinal cord.</p>

Effect of electroacupuncture on pain threshold and spinal NR2B subunit expression in a rat model of neuropathic pain / 南方医科大学学报

<p><b>OBJECTIVE</b>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.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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 (P<0.05). EA obviously alleviated the hypersensitivity in the rats with CCI and inhibited spinal NR2B expressions (P<0.05). 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 (P>0.05).</p><p><b>CONCLUSION</b>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.</p>