Abstract:

Objective To explore the influence of intrathecal postsynaptic density protein 95(PSD-95) gene specific siRNAs on CaMKⅡα phosphorylation in spinal cord of rats with neropathic pain. Methods The NG108-15 neuroal cells were transfected with chemically synthesized siRNA targeting PSD-95 for comprehensive evaluation of its silence efficacy. Ninety-one adult male Sprague-Dawley rats were randomly divided into three groups: naive, sham and sciatic nerve chronic constriction injury (CCI) group. All the rats in CCI group were subdivided into four groups, which were treated with normal saline（control group）, transfection vehicle（vehicle group）, mismatch siRNAs（mmRNA group）and PSD-95 gene specific siRNAs（siRNA group）respectively. All the subgroup received corresponding agents intrathecally for 3 days, as was started 5 days after the chronic constriction injury of sciatic nerve. Mechanical withdrawal threshold (MWT) was measured on post intrathecal infusion day 1, 3 and 7 by a series of von Frey hairs. The rats were sacrificed at different times after intrathecal infusion to examine PSD-95 and phosphorylation of CaMKⅡα in the lumber 4-6 spinal cord by Western blotting. Results The siRNAs, which was exclusively identical to PSD-95, decreased PSD-95 level significantly in NG108-15 cells. The MWT of neuropathic pain rats increased significantly after intrethecal administration of PSD-95 specific siRNA ( P <0.05), compared with intrethecal injection of saline. Total CaMKⅡα level did not change after PSD-95 siRNA infusion（ P >0.05）, however, the pThr286 CaMKⅡα level on the spinal cord of the CCI rats decreased significantly ( P <0.05). Conclusion Administration of PSD-95 gene specific siRNAs attenuates the phosphorylation of CaMKⅡα Thr286 and central sensitization signaling cascades and results in the relief of neuropathic pain.

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