Figure 1 - Hypoalgesia in the formalin test after induction of tonic immobility (TI). Mean number of flinches (A) and lickings (B) per 10-min period in phase 1 (0-10 min after injection of formalin) and phase 2 (20-60 min) of the formalin test for the control group (control, N = 8), after TI induction (TI, N = 8) and for the group pretreated with naloxone and submitted to TI induction (Nal + TI, N = 8). The vertical bars indicate the standard error of the mean. *P<0.05 compared to control and to the Nal + TI group (Duncan test).