Changes in expression of PKCγ in spinal dorsal horn in a rat model of bone cancer pain

Abstract

Objective To investigate the changes in expression of protein kinase Cγ (PKCγ) in the spinal dorsal horn in a rat model of bone cancer pain (BCP). Methods Forty-eight female adult Wistar rats weighing 180-200 g were randomly divided into 3 groups (n = 16 each): group Ⅰ control (group C); group Ⅱ sham operation (group S) and group Ⅲ BCP. In group BCP Walker 256 mammary gland cancer cell suspension 10 μl was injected into left tibia, while in group S heat-inactivated Walker 256 mammary gland cancer cell suspension 10 μl was injected into the same region. Mechanical pain threshold of hind paw was measured every 3 d from 1 d before operation to 21 d after operation, and then the rats were killed at 1 d before and 6, 15 and 21 d after operation (4 rats at each time point) and the L4-6 segment was removed for determination of PKC7 expression (by immuno-histochemistry). Results PKCγ expression was up-regulated after operation and reached the highest value at 15 d after operation as compared with that at 1 d before operation in group BCP (P < 0.05). Mechanical pain threshold was significantly decreased and PKCγ expression was up-regulated in group BCP as compared with group C and S (P<0.05). PKCγ expression was negatively correlated with mechanical pain threshold (r=-0. 984, P < 0.05). Conclusion The expression of PKCγ is up-regulated in spinal dorsal horn in the rat with BCP, the up-regulation of PKGγ expression may be involved in the maitenance of BCP. Key words: Bone neoplasms; Pain; Protein kinase C; Spinal cord