Effects of nicotine on pain and aggressivity and antagonism of these effects by mecamylamine

Nicotine caused a dose-dependent decrease [1.25 and 2.5 mg/kg] on writhing score of the mice, made painful by intraperitoneal [i.p.] acetic acid injection. At the dose of 0.75 mg/kg i.p. nicotine lowered attack score and time of the mice but there wasn't a significant change at 0.5 mg/kg dosage. These effect of nicotine were blocked by 2.5 mg/kg mecamlamine which was given 15 minutes before nicotine administration