Effect of Intrathecal Ketamine Injection on the Expresstion of NMDA-2B Protein in the Spinal Cord on Rat Models by Chronic Constriction Injury

Objective To evaluate the effect of intrathecal ketamine(KET) on the expression of NR2B protein in the spinal cord of chronic constrction injury(CCI) rats.Methods Eighteen male Spragru-Dawley rats were randomly divided into 3 groups: In sham operation group the animals were shamly operated;In CCI group the rats were placed four loose ligatures around the right sciatic nerve;In CCI+KET group ketamine 1 mg/kg was administered 30 min before and 1,2,3,5,7,9,11 days after operation.Rats were tested for hyperalgesia by measuring paw withdrawal latency(PWL) using von-Frey filaments and ice-cold water.The changes in NR2B protein expression in the spinal cord was detected by immuno-histochemical techniques.Results The expression of NR2B protein in the spinal cord was minimal in sham operation group;CCI induced significant increase in the expression of NR2B protein in the ipsilateral spinal cord and ketamine intrathecal significantly inhibited the increase in NR2B protein expression.There was significant difference between sham group with CCI and CCI+KET groups(P0.01).Conclusions Upregulation of NR2B expression may be involved in the development of neuropathic pain and inhibition of NR2B expression may contribute to the antinociceptive effects of ketamine.