Nicotine attenuates DOI-induced head-twitch response in mice: Implicationsfor Tourette syndrome

I Tourette syndrome (TS), a chronic neuropsychiatric disorder, is character ized by motor and vocal ties. Preliminary clinical studies indicate possibl e therapeutic benefits of nicotine in the treatment of Tourette's syndrome (TS). It has been proposed that twitches of the head in mice or twitches of head and shoulders in rats following administration of the selective 5HT(2 A/c) agonist DOI (1-)2,5-dimethoxy-4-iodophenyl-2-aminopropane, can serve a s an animal model of ties in TS. 2. In this study, the effects of acute and chronic administration of nicoti ne on DOI-induced head twitch response (HTR) in male albino ICR mice were e valuated. 3. Both acute and chronic nicotine (daily injections for 10 days) reduced t he DOI-induced HTR. Moreover, chronic administration of DOI (1 mg/kg/day fo r 10 days) resulted in 65% increase in [I-125]alpha -bungarotoxin binding i n cerebellum and 41% increase in striatal [H-3]cytisine binding. However, t he acute inhibitory effects of nicotine were not blocked by pretreatment wi th the nicotinic antagonist, mecamylamine. Indeed, at higher doses, mecamyl amine also reduced the DOI-induced HTR. 4. The data suggest that both nicotine and mecamylamine may be of therapeut ic potential in the treatment of some symptoms of TS.