Fig. 3.
The DOR antagonist BNTX increases the potency of U50488 for reduction of PGE2-evoked thermal allodynia, and the BNTX effect is blocked by NTI. Rats were injected (intraplantar) with BK (25 μg) in combination with vehicle (Veh), BNTX (1 μg), or NTI (40 μg) plus BNTX (1 μg) 15 minutes before intraplantar injection with PGE2 (0.3 μg) with or without U50488 at the indicated doses. Paw withdrawal latencies are expressed as the change (seconds) from individual baseline values 10 minutes after PGE2/U50488 administration and represent the mean ± S.E.M. of 6–12 animals per group. Data were analyzed for statistical significance using two-way ANOVA. The U50488 curve in the presence of BNTX was significantly different from Veh (F(1, 121) = 4.08, P = 0.04). By contrast, the U50488 curve in the presence of BNTX and NTI in combination was not different from Veh (F(1, 89) = 3.177, P = 0.08). Full time-course curves are presented in Supplemental Fig. 6. *P < 0.05; ***P < 0.001 vs Veh.