Role of spinal cord TNF-α in the development of bone cancer pain in mice

Objective To investigate the role of spinal cord TNF-a in the development of bone cancer pain in mice. Methods Seventy-two 4-6 week old C3H/He mice weighing 18-25 g were randomly divided into 3 groups (n = 24 each) : group I sham operation (group S) ; group II bone cancer pain (group BCP) and group Ⅲ etanercept (group E). Bone cancer pain was induced by implantation of osteosarcoma NCTC 2472 cells into the intramedullary space of right femur in group II and Ⅲ . Group Ⅲ received intraperitoneal etanercept 100 μg at 3 days before and immediately before and day 3 and 6 after tumor cell inoculation. In group S culture medium α-MEM containing no cancer cell was injected instead. The paw withdrawal threshold to mechanical stimuli (PWMT) and paw withdrawal latency to thermal stimuli ( PWTL) were measured before inoculation (baseline) and at day 3, 5,7, 10, 14 after inoculation respectively. Eight animals were killed on the 7th, 10th, and 14th day after inoculation in each group. The spinal cords were removed and TNF-α mRNA expression in the spinal cord was determined by RT-PCR. Results Cancer pain was significantly attenuated by pretreatment with etanercept. The TNF-α mRNA expression in the spinal cord was significantly increased after inoculation and was significantly attenuated by pretreatment with etanercept in group Ⅲ . Conclusion Spinal cord TNF-a is involved in the development of bone cancer pain in mice.