Expression of mRNA and protein of complement 3 in spinal dorsal horn of rats with neuropathic pain / 解放军医学杂志

ABSTRACT

Objective To investigate the characteristic changes in the mRNA and protein of complement 3 in spinal dorsal horn of rats with neuropathic pain,and the role of abnormal activation of complement protein in the mechanism of pain production.Methods Eighty-four healthy male SD rats were divided randomly into seven groups(n=12 for each group)normal control group,sham-operation 1d,3d and 7d groups,and chronic constriction injury of the sciatic nerve(CCI)1d,3d and 7d groups.The left sciatic nerve was ligated loosely in CCI groups,while it was only exposed but not ligated in rats in sham-operation groups.The mechanical and thermal pain thresholds were measured on 1,3 and 7 days after operation,and the mRNA and protein of complement 3 in the dosal horn of the spinal cord were determined respectively by RT-PCR,immunoturbidimetry and immunohistochemistry.Results The mechanical and thermal pain thresholds were observed to be lowered in rats one day after the sciatic nerve ligation,and a state of hyperalgesia was found to be persistent up to 7 days after CCI.This symptom was not observed in sham operation group.The expression of mRNA and protein of complement 3 in spinal dorsal horn were increased on 1,3 and 7 days after CCI.Interestingly,a high expression of mRNA of complement 3 was also observed in rats one day after sham-operation.Both mRNA and protein of complement 3 were not obviously elevated in rats of sham operation 3d,7d groups and normal control group.Conclusion The mRNA and protein of complement 3 in spinal dorsal horn are highly up-regulated in rats with neuropathic pain,suggesting that the characteristic dynamic changes in complement may contribute to the establishment and maintenance of hyperalgesia.