Figure 5

nAChR antagonists block Artn-induced heat hyperalgesia. A. WT (n = 4) and ART-OE (n = 6) mice were injected with either 10 μl saline (right foot) or 10 μl Mec (left foot, 1 mg/kg) and latencies of withdrawal measured for each foot 60 min post injection. As previously reported [10], ART-OE mice exhibit lower heat thresholds compared with WT mice (compare saline treated groups). Mec partially blocks heat hyperalgesia in ART-OE mice (p < 0.05, ANOVA) and did not affect thermal sensitivity in WT mice. B. Footpads of WT mice were injected with 1 mg/kg Mec or saline 30 min prior to injection of Artn (200 ng) or saline. Mec injection had no effect on thermal sensitivity. Artn injection alone increased heat hyperalgesia whereas Mec + Artn blocked hyperalgesia. C. Mice (n = 6) were injected in the left footpad with saline (10 μl) 30 min prior to Artn injection (200 ng). Other mice (n = 6) were injected with HEX (10 μl, 1 mg/kg) followed by Artn. A third set (n = 6) were injected with HEX followed by saline. HEX alone did not affect thermal sensitivity. HEX blocked thermal sensitivity caused by Artn at 1 h, 3 h and 5 h post injection. Measures were made in a blinded manner. Asterisks indicate p < 0.05.