Role of spinal cord neuronal restrictive silencing factor in development of bone cancer pain and its relationship with N-methyl-D-aspartate receptor subunit 2B expression in mice

Abstract

Objective To evaluate the effect of spinal cord neuronal restrictive silencing factor (NRSF) in the development of bone cancer pain and its relationship with N-methyl-D-aspartate receptor subunit 2B (NR2B) in mice. Methods Ninety-six SPF adult male mice (C3H/HeJ) were randomly divided into bone cancer pain group (Group BCP, n=24), NRSF antisense oligodeoxynucleotide (AS-ODN) group (Group AS-ODN, n=24), artificial cerebrospinal fluid (ASCF) group (Group ACSF, n=24) and sham-operated group (Group S, n=24). Suspension with 2×105 NCTC2472 fibrosarcoma cells were injected into the medullary cavity of right distal femur to induce bone cancer pain of mouse models in the former three groups; mice in Group S were injected only a-MEM; before and 2, 4 and 6 d after inoculation, mice in the Group AS-ODN were given 5 μL artificial cerebrospinal fluid containing AS-ODN 10 μg via intrathecal injection, and mice in the Group ACSF were given ACSF only. (1) All mice were tested for pain-related behaviors before inoculation (T0) and 5 d (T1), 7 d (T2), 10 d (T3) and 14 d (T4) after inoculation, including paw withdrawal mechanical threshold (PWMT) and paw withdrawal thermal latency (PWTL). (2) Lumbar intumescentia of mice in all groups was taken to investigate the expression levels of NR2B and NRSF by Western blotting after pain behavior tests at T1, T2, T3 and T4 time points. Results (1) As compared with that in Group S, the PWMT in Group BCP and ACSF was significantly decreased at T2, T3 and T4 time points, while PWTL was significantly decreased at T3 and T4 time points (P<0.05); both PWMT and PWTL in Group AS-ODN were significantly decreased as compared with those in Group S at T1, T2, T3 and T4 (P<0.05); as compared with those in the Group BCP, PWMT and PWTL in Group AS-ODN decreased significantly at T1 and T2 time points (P<0.05). (2) As compared with Group S, the NR2B expression in Group BCP, AS-ODN and ACSF was significantly increased at T1, T2, T3 and T4, while the NRSF expression was statistically decreased (P<0.05); as compared with that in Group BCP, the NR2B expression increased significantly at T1 and T2 time points, while the NRSF expression was significantly decreased in Group AS-ODN (P< 0.05). Conclusion NRSF plays an important role in the development of bone cancer pain in spinal cord in mice, whose regulation mechanism of NRSF on NR2B might take part in the formation of bone cancer pain. Key words: Bone neoplasm; Chonic pain; Neuronal restrictive silencing factor; N-methyl-D-aspartate receptor subunit 2B