Fig. 5. The anti-allodynic effect of DPDPE is mediated by delta opioid receptors and is PKC-dependent.

Animals received either bradykinin (BK; 25 μg) or bradykinin with naltrindole (NAL; 40 μg) 15 min prior to the co-injection of PGE₂ (0.3 μg) and DPDPE (20 μg) or vehicle (first four bars). In another experiment, separate groups of animals were pretreated with either chelerythrine (CHEL; 5 μg) or BIS (25 μg; 100 μl) 30 min prior to treatment with either vehicle or bradykinin (BK; 25 μg); 15 min after vehicle or bradykinin, animals were co-injected with PGE₂ (0.3 μg) and DPDPE (20 μg; last four bars). PWLs were measured at 5 min intervals for at least 20 min after the last injection. Baseline PWLs were 10.50 ± 0.31 s. Data are represented as mean ± S.E.M. PWL measured 10 min after the last injection of 5–9 animals per group. ***, P<0.001 vs. all other groups.