Expression Of PJNK In Spinal Dorsal Horn Of Bone Cancer Rats And Antinociceptive Effects Of Its Inhibitor

Part one: Expression of pJNK in Spinal Dorsal Horn of Bone Cancer RatsObjective To investigate the expression of pJNK in spinal dorsal horn of bone cancer rats.Methods Female SD rats weighing 150-170 g were used in this study. 36 animals were randomly divided into 6 groups(n=6 each): sham 7d group , model 7d group, sham 10d group,model 10d group,sham 18d group,model 18d group. sham group inject normal sodium 5μl into tibia medullary cavity, model group inject walker 256 cells (2×107/ml) 5μl into tibia medullary cavity; The animals were killed at respective day and L4,5 lumbar segment of the spinal cord was removed and kept at -80℃for determination of pJNK expression in the dorsal horn by immunohistochemistry.Results The expression of pJNK in spinal dorsal horn was significantly increased after bone cancer pain.Conclusion The expression of pJNK in spinal dorsal horn was significantly increased from 10 day to 18 day after bone cancer pain .The pJNK play an important role in bone cancer pain possiblely. Part two: Effect of lntrathecal SP600125 in rats of bone cancer pain on mechanical hyperalgesiaObjective To investigate the effect of the specific JNK inhibitor SP600125 in a rat model of bone cancer pain on mechanical withdraw threshold(MWT) of the injuried hind paw .Methods Female SD rats weighing 150-170 g were used in this study.32 rats were randomly divided into 4 groups(n=8 each): sham group, model group, DMSO group and SP600125 group.Sham group inject normal sodium 5μl into tibia medullary cavity, other groups inject walker 256 cells (2×107/ml) 5μl into tibia medullary cavity; set pipes into subarachnoid space of all rats after establishing model 1d; DMSO group intrathecal inject DMSO (5%) 10μl, SP600125group intrathecal inject SP600125 (0.5‰) 10μl, other two groups do not intrathecal inject anything after establishing model 10d. Response of the injuried hind paw to mechanical stimulation with von-Frey filament (MWT) was measured before and after establishing model 3d,5d,7d,10d and at 1,2,3,6,12 and 24 h after intrathecal SP600125 injection.Results The mechanical hyperalgesia emerged after estalishing model 7d and became more and more severe. After intrathecal SP600125 administration 1,2,3,6,12h MWT increased significantly. 3 h after intrathecal administration was the summit of SP600125 effect. Although at the summit, MWT couldn't come back to the baseline.Conclusion Intrathecal administration of SP600125 can attenuate but cann't inhibit the mechanical hyperalgesia induced by bone cancer pain completely.