The expression of NR2B subunit of the NMDA receptor in the spinal cord of rats with neuropathic pain

Objective To investigate the change of protein level of NR2B subunit of the NMDA receptor in the spinal cord dorsal horn of rats with neuropathic pain.Methods Male Sprague-Dawley rats weighing 180-200 g were divided into four groups with 10 rats each:sham-operation group(C);3 d group(Ⅰ);7 d group(Ⅱ)and 14 d group(Ⅲ).Peripheral mononeuropathy was produced by loosely ligating the rat's common sciatic nerve,a procedure which causes chronic constrictive injury(CCI)of the ligated nerve.In sham-operated animals,the same dissection was performed but without ligation.The mechanical pain thresholds of the rats before and after the operation were determined with a Von Frey hair test.The change of protein level of NR2B subunit in the spinal cord dorsal horn was detected with Western blot method.Results Compared with group C,CCI rats exhibited lower mechanical pain thresholds on the 7th and the 14th day after nerve ligation(P0.05).The protein levels of NR2B subunit in group Ⅱ and group Ⅲ were higher than those in group C.There was no change of mechanical pain thresholds or protein levels of NR2B subunit in group Ⅰ.Conclusion The data indicate that the protein levels of NR2B subunit in spinal cord of rats with neuropathic pain were higher,which may be one of the causes of neuropathic pain.