Figure 4.

Dose–response curves for morphine, WIN, and GP1a in the rat carrageenan test. Rats received a carrageenan injection into the paw. WIN or GP1a was injected intraperitoneally 15 min before and 195 min after the carrageenan injection. Morphine was injected at 210 min post‐carrageenan subcutaneously into the dorsal flank. Analgesia was assessed 30 min after morphine injection using the Hargreaves' apparatus with a radiant heat beam. (a) Morphine provided analgesia at all but the lowest dose. *P < .05, significantly different from vehicle; one‐way ANOVA followed by Sidak's multiple comparison test. (b) WIN: percentage of maximal analgesia. (c) GP1a: percentage of maximal analgesia. (b, c) Not significant by one‐way ANOVA compared to vehicle