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. 2009 Mar 9;106(12):4917–4922. doi: 10.1073/pnas.0811586106

Fig. 3.

Fig. 3.

Analgesic characterization of exon 11 knockout mice. (Upper) Radiant heat tail-flick assay. Groups of mice (n = 16–24) receive morphine (4 mg/kg, s.c.), methadone (2 mg/kg, s.c.), M6G (2 mg/kg, s.c.), heroin (1 mg/kg, s.c.), or fentanyl (0.5 mg/kg, s.c.) and test in the tail-flick assay at 15 min (heroin) or 30 min (morphine, methadone, M6G, and fentanyl). Responses in wild-type and knockout animals are compared for each drug separately by using the Fisher exact test. (Lower) Hot-plate assay. After determining baseline latencies for all animals to the first pain response (licking or jumping), groups of mice (n = 10–15) receive either morphine (2.5 mg/kg, s.c.) or M6G (1.5 mg/kg) and are tested for analgesia on a 52 °C hot plate 15 min later. The latencies are determined and converted to %MPE [(latency − baseline)/(maximal latency − baseline)]. ANOVA is used to compare morphine-treated groups and to compare M6G-treated groups.