Fig. 5.

Nicotinic receptor subtypes involved in PNU-120596–induced antinociception in the formalin test. Blockade of the antinociceptive effect of PNU-120596 during phase 1 (A) and phase 2 (B) of the formalin test by different nicotinic antagonists. Mice were treated with MLA (10 mg/kg s.c.) or DHβE (2 mg/kg s.c.) 15 minutes before an active dose of 4 mg/kg PNU-120596. Fifteen minutes later, mice were injected with formalin (2.5% intraplantar, 20 μl) and then observed for pain behaviors. Antinociceptive effects of PNU-120596 in the formalin test were tested in α7 WT and KO mice. α7 WT and KO mice received an i.p. dose of 4 mg/kg PNU-120596 and were tested 15 minutes later during phase 1 (C) and phase 2 (D) of the formalin test. Data are mean ± S.E.M. licking time for six to eight mice/group. *P < 0.05 versus vehicle-vehicle group. PNU, PNU-120596; Veh, vehicle.