Effects of STZ and DSP-4 on thermal and mechanical nociception. Time course of thermal hyperalgesia (A) and mechanical allodynia (B) in the rats treated with STZ and vehicle. At week 0, rats received an i.v. injection of STZ (n = 20 rats) or vehicle (n = 20) (arrow on the left-bottom). At 4 weeks after STZ injection, the rats received an i.p. injection of DSP-4 (n = 10 rats) or saline (n = 10) (black arrowhead). The mean and SEM (vertical bars) values of 10 rats for each experimental group are shown. **P < 0.01; ***P < 0.001 (ANOVA repeated-measures) between STZ-treated (circles) and vehicle-treated (squares) groups; ###P < 0.001 (ANOVA repeated-measures) between vehicle + saline (open squares) and vehicle + DSP-4 (filled squares) groups; NS, not significantly different (ANOVA repeated-measures) between STZ + saline (open circles) and STZ + DSP-4 (filled circles) groups.