Fig. 4.

Effects of κ-ODN treatment on peripheral antinociceptive actions of μ-ORA (DAMGO) and δ-ORA (deltorphin) in the formalin flinch test. One hundred nanomoles of drug were administered 10 min before formalin in the dorsal surface of the rat hindpaw. A illustrates the time course of the formalin-induced flinching response; the data are summarized inB. Both DAMGO and deltorphin significantly attenuated the second phase flinching response (p < 0.05). Administration of KOR antisense ODN had no effect on the antinociceptive actions of either of these two drugs.