Fig. 1.
Effects of systemic administration of cebranopadol on thermal nociception and itch-scratching responses in monkeys. Time courses of cebranopadol-induced (A) and fentanyl-induced (B) antinociception against an acute noxious stimulus (50°C water). (C) Time courses of itch scratching responses elicited by cebranopadol (5.6 μg/kg) and fentanyl (30 μg/kg) at antinociceptive doses. (D) Effects of μ receptor antagonist naltrexone (0.03 mg/kg) and nociceptin receptor antagonist J-113397 (0.1 mg/kg) on cebranopadol-induced antinociception. (E) Effects of δ receptor antagonist naltrindole (1 mg/kg) and κ receptor antagonist 5′-guanidinonaltrindole (1 mg/kg) on cebranopadol-induced antinociception. All drugs were delivered subcutaneously. Data represent the mean ± SD (n = 6 [A, C]; n = 4 [B, D, E]) and were analyzed by two-way repeated measures ANOVA followed by the Dunnett multiple comparison test. *P < 0.05, significantly different from the vehicle condition.