The role of PKCγ subunit of rACC neurons in the development of bone cancer pain in rats

Background: To explore the role of PKCγ subunit of rACC neurons in the development of bone cancer pain in rats. Methods: 32 adult female SD rats were divided into four groups: blank control group (Naive group), sham operation group (Sham group), bone cancer pain group (BCP group) and PKCγ/shRNA recombinant lentiviral vector group (PKCγ group). 10μl MADB-106 rat mammary cancer cells suspension, 10μl saline was inoculated into the proximal tibia bone marrow cavity of rats in BCP group and Sham group respectively. In the PKCγ group, the rats were taken the same treatment as the BCP group, and then 10μl shRNA/NR2B recombinant lentivirus was injected into the bilateral rACC on the 7th day. The mechanical withdrawal threshold and thermal withdrawal latency were measured every 3 days to assess the rat pain behavior. Immunohistochemistry and Western blotting technology were used to detect the expression of PKCγ subunits in rat rACC neurons after operation. Results: There was no significant difference in the mechanical withdrawal threshold and thermal withdrawal latency between the four groups (P>0.05). From the 3rd day after operation, the mechanical withdrawal thresholds in BCP group and PKCγ group were significantly decreased than those in Naive group and Sham group (P<0.05). Compared with the BCP group, the mechanical withdrawal threshold in the PKCγ group increased significantly (P<0.05). On the 3rd postoperative day, the thermal withdrawal latency in BCP and PKCγ groups was significantly longer than those in Naive and Sham groups（P＜0.05). From the 10th postoperative day, the thermal withdrawal latency in PKCγ group was shorter than that in BCP group (P<0.05). Western blot analysis showed that the expression of PKCγ in rACC neurons on the 14th day after operation in rats of BCP group was significantly higher than that in Naive group and Sham group. (P<0.05) However, in the PKCγ group, the expression of PKCγ in rACC neurons was significantly lower than that in BCP group (P<0.05). Conclusion: Up-regulation of PKC subunit of rACC neurons in bone cancer pain rats may be involved in the development of pain sensitivity in bone cancer. Key words: Bone cancer pain; rat; rACC; PKCγ; gene silencing