The role of CaMKII in neuropathic pain and fear memory in chronic constriction injury in rats.

Purpose/Aim of the study In this study, we sought to observe the effects of Ca2+/calmodulin-dependent protein kinase II (CaMKII) on neuropathic pain and fear memory in a rat model of chronic constriction injury (CCI). Materials and methods Rats were randomly divided into the Sham, Control, CCI and m-AIP groups. In the m-AIP group, an intrathecal injection of m-AIP, the specific antagonist of CaMKII, was given either pretreatment or posttreatment in rats. Mechanical allodynia and thermal hyperalgesia tests were used to test pain behavior, and the passive avoidance test was used to measure fear memory in rats. Results The right side of hippocampus tissues were taken at varying time points. The expression levels of CaMKII-α, pCaMKII-α, CaMKII-β, pCaMKII-β, NR2A, pNR2A, NR2B and pNR2B were detected by Western blot analysis. Significant pain behaviors and impaired cognitive function were shown after CCI surgery, accompanied by the upregulation of proteins in the hippocampus. Pretreatment with m-AIP appeared to provide a temporary improvement in pain and fear memory and decreased the expression of the above proteins in the hippocampus seven days after surgery. Furthermore, postoperative treatment with m-AIP provided relief for pain behavior and protein expression but did not affect fear memory. Conclusions These data suggested that CaMKII played an important role in the crosstalk between neuropathic pain and fear memory, indicating that CaMKII may be a potential therapeutic target for neuropathic pain treatment.