Tail-flick reaction time of control rats injected with (A) vehicle or capsazepine (10 mg/kg, i.p. or 10 μg/site, i.t.) or (B) vehicle or SB366791 (1 mg/kg, i.p. or 30 μg/site, i.t.). Tail-flick reaction time was assessed using either a tungsten lamp (A) or a hot water bath (50°C) as a heat source (B). Data represent the means ± S.E.M. of 4 rats per group.