Changes in expression of NF-κB, IL-6 and TNF-α in spinal cord in a rat model of bone cancer pain

Objective To evaluate the changes in expression of NF-κB, IL-6 and TNF-α in spinal cord in a rat model of bone cancer. Methods Seventy-two female SD rats weighing 150-180 g were randomly divided into 3 groups (n = 24 each): control group (group C);sham operation group (group S) and bone cancer pain group (group BP). Bone cancer was induced by intra-tibial inoculation of 1 × 105 Walker 256 breast cancer cells. Paw withdrawal threshold to mechanical stimulation was measured with yon Frey filaments. The expression of NF-κB p65, IL-6 and TNF-α mRNA in the spinal cord was determined by RT-PCR and the expression of NF-κB p65 by immuno-histochemistry and NF-κB p65 positive cell count was determined. Results The paw withdrawal threshold was significantly lower and the expression of NF-κB p65, NF-κB p65 mRNA, IL-6 mRNA, TNF-α mRNA and NF-κB p65 positive cell count in the spinal cord were significantly higher in group BP than in group C and S ( P ＜0.05 or 0.01 ). Conclusion Intra-tibial inoculation of Walker 256 breast cancer cells activates NF-κB in the spinal cord, leading to the increased release of IL-6 and TNF-α and mechanical hyperalgesia. Key words: Bone neoplasms; Pain; NF-kappa B; Interleukin-6; Tumor necrosis factor-alpha