Participation of spinal CaMKII-NR2B signal pathway in the development of bone cancer pain in mice

Abstract

Objective To investigate the effect of KN93, a CaMKII inhibitor, on the spinal NR2B expression in the bone cancer pain mouse and its underlying mechanism. Methods Thirty-six male C3H/HeJ mice were randomly divided into 3 groups: sham group(S, n=8), bone cancer pain group(BP, n=8) and KN93 group(K, n=20). The mouse model of bone cancer pain was established by intra-femur inoculation of osteolytic NCTC 2472 cells in BP and K groups. At 14d post operation, mice in K group received intrathecal injection of 60nmol KN93/5μl in 20%DMSO and mice in BP group and S group received 20% DMSD 5μl respectively.Eight mice were selected randomly from each group at 1d before inoculation, at 1h before administration and at 1, 2, 4, 24h after administration(T0-5) to be measured the paw withdrawal threshold(PWT) stimulated by von Frey filaments. Another 3 mice were sacrificed at the corresponding time point and the spinal cord L3~5 were obtained for determination of NR2B expression by western blot. Results PWT was significantly decreased in group BP((0.50±0.11)g) and K((0.52±0.10)g), except for group K at T3(P>0.05), and NR2B expression up-regulated at T2-5 in BP(1.78±0.34), K groups ((1.11±0.14), (0.73±0.03), (1.11±0.15), (1.89±0.32)) compared with S group((1.78±0.31)g, (0.33±0.04), P 0.05). Conclusion Intrathecal injection of KN93 can attenuate bone cancer pain in mice through inhibiting NR2B with a time-dependent manner and spinal CaMKII-NR2B pathway may participate in the development of bone cancer pain. Key words: Calcium/calmodulin-dependent protein kinase II; NR2B; Bone cancer pain