Changes in protein expression and distribution of spinal CCR2 in a rat model of bone cancer pain

Accumulating evidence suggests that chemokine C-C motif receptor 2 (CCR2) plays an important role in neuropathic pain. It has been shown that spinal CCR2 is upregulated in several neuropathic pain models and expressed by neuronal and glial cells in the spinal cord. In this study, we investigated the expression changes and cellular localization of spinal CCR2 in a rat model of bone cancer induced by Walker 256 cell inoculation. The present results indicated that mechanical allodynia progressively increased in bone cancer pain (BCP) rats. Western blot and immunohistochemical analysis demonstrated that the expression of CCR2 in the spinal cord was significantly increased on day 6, 12, and 18 in BCP rats, with a peak on day 6. Furthermore, double immunofluorescence labeling indicated that CCR2 was expressed by both microglia and neurons in the spinal cord. These results suggest that CCR2 may be involved in the development of BCP, and that targeting CCR2 may be a new strategy for the treatment of BCP.