Fig. 6.

Effect of mice pre-treatment with naloxone (2 mg/kg, i.p.) on the antinociceptive effect of a supercritical CO₂ extract of Aloysia gratissima leaves (EAG) (10 mg/kg) on the formalin test. Nociceptive behavior in the first phase (A, 0–5 min) or second phase (B, 15–30 min) of the test. Morphine (5 mg/kg, s.c.) was used as positive control. Results expressed as mean ± S.E.M. (n = 4–7 mice/group). Two-Way ANOVA followed by Student-Newman-Keuls test, ∗p < 0.05; ∗∗p < 0.01; ∗∗∗p < 0.001 compared to the vehicle plus vehicle-treated group. ##p < 0.01 compared to the vehicle plus morphine-treated group; §p < 0.05; §§p < 0.01 compared to the vehicle plus naloxone-treated group and morphine plus naloxone-treated group.