Figure 1

Behaviors recorded during the formalin test (60 min). Spontaneous behaviors: (A) activity duration (sec) and (B) rearing frequency (n). Pain-related behaviors: (C) flexing duration, (D) licking duration and (E) paw-jerk frequency recorded in male rats treated with morphine (MOR) or saline (SAL) three hours before the formalin test in the dorsal hind paw. Data are shown as mean ± SEM.