NICOTINE POTENTIATES SULPIRIDE-INDUCED CATALEPSY IN MICE

The effects of nicotine on sulpiride-induced catalepsy in mice were in vestigated. Sulpiride (12.5-100 mg/kg) induced a low degree of catalep sy in mice which was dose dependent. Nicotine (0.0001-1 mg/kg) caused an even lower degree of catalepsy. When the drugs were co-administered a much higher cataleptogenic response was obtained. The potentiation of the effect of sulpiride by nicotine was elicited by 0.5 mg/kg or hi gher doses of the drug. The central nicotinic receptor antagonist meca mylamine (1-3 mg/kg) and the peripheral antagonist hexamethonium (5 an d 10 mg/kg) decreased the response induced by the combination of nicot ine and sulpiride. Higher doses of the cholinoceptor antagonist atropi ne (10 mg/kg) also reduced the catalepsy induced by the drug combinati on. It is concluded that nicotine potentiates sulpiride-induced catale psy through activation of cholinergic mechanism(s) and that the centra l nicotinic mechanism mediates nicotine's action.