Figure 4. The antinociceptive activity of atomoxetine in the rat formalin model was independent of µ-opioid receptor activation.

The µ-opioid receptor antagonist naloxone (Nal, IP, 5 mg/kg), at a dose which effectively blocked morphine (Mor)-induced analgesia in the rat formalin model, did not inhibit atomoxetine (Atx)-induced antinociception (n = 5–7). All values are shown as mean ± SEM for each group and are expressed as percentage of controls. Student’s t test, t ₍₁₀₎ = 7.668, ***p<0.001.