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Abstract: Ｏｂｊｅｃｔｉｖｅ To investigate the effect of KN93， an inhibitor of Ca2+/calmodulin dependent protein kinase Ⅱ（CaMKⅡ）， on the neuropathic pain of the chronic compression of dorsal root ganglion（CCD） model rats. Methods Forty-eight male SD rats were randomly divided into 3 groups： sham group （group S， n=11）， CCD model group （group C， n=11）， KN93 group （group K， n=26） . Group C and group K were operated with the model of neuropathic pain induced by CCD， group S were treated as sham operated rats. Fourteen days after operation， group S and group C received intrathecal injection of 10% dimethyl sulfoxide（DMSO） 25 μl， while group K received intrathecal injection of 50 μg KN93 dissolved in 25 μl 10% DMSO. Pain behavior tests including paw withdrawal thermal latency（PWTL） and paw withdrawal mechanical threshold（PWMT） were detected on eight rats randomly selected from each group before（t1） and 4（t2）， 7（t3）， 10（t4）， 14 d（t5） after operation. Group S， group C and group K also received the same tests 2（t6）， 4（t7）， 10（t8）， 12（t9）， 24 h（10） after administration of DMSO or KN93. In all three groups before administration and in group K after administration at each time point（t6-t9）， 3 randomly selected rats were sacrificed and each expansion part of spinal cord was obtained. Western blot was used to detect the expression level of CaMKⅡ protein. Results From t6 to t9 after administration， group K PWTL［（14.7±1.6）， （18.6±1.8）， （21.2±2.5）， （15.3±2.0） s］ and PWMT［（12.0±1.0），（15.4±1.4）， （17.5±1.7）， （14.9±1.6） g］ were increased when compared with group C PWTL［（11.6±1.8）， （10.7±1.7）， （11.7±2.4），（9.9±1.7） s］ and PWMT［（8.4±0.9）， （9.6±1.6）， （10.6±1.7）， （8.9±1.3） g］（P<0.05）. Before and 24 h（t10） after administration， group K PWTL and PWMT had no significant difference when compared with group C（P>0.05）. Compared to the basic value（t5）（1.55±0.12） prior to the administration， the expression of CaMKⅡ from t6 to t9［（1.37±0.11）， （1.15±0.12）， （0.75±0.08）， （0.86±0.12）］were significantly decreased（P<0.05）. Conclusions Intrathecal administration of KN93 may play an important role in relieving pain of neuropathic pain rats.
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