Fig. 5.

Analgesic effect of intraperitoneal injection of a single dose of Tempol on established cancer-induced bone pain (CIBP). A single dose of Tempol (10, 100, 200 mg/kg, i.p.) was given on day 14 after surgery. The behavioral tests were conducted at 0, 0.5, 1, 2, 4 and 6 h after Tempol injection. i.p. injection of Tempol at the dose of 10 mg/kg had no significant effect on the PWTs (p > 0.05 compared with the vehicle group). However, i.p. injection of Tempol at the dose of 100 and 200 mg/kg notably upregulated the PWTs in CIBP rats, beginning at 0.5 h, peaking at 1 h and lasting for at least 2 h (*p < 0.05, ***p < 0.001 compared with the vehicle group, #p < 0.05 compared with the group treated with Tempol 100 mg/kg, n = 6 in each group).