[Effect of Y-516 on the hyperactivity induced by dopamine injected bilaterally into the nucleus accumbens]

The effect of Y-516 on the hyperactivity induced by dopamine injected bilaterally into the nucleus accumbens was compared with those of clocapramine (CCP), haloperidol (HPD) and chlorpromazine (CPZ). Dopamine (5-50 micrograms) injected into the nucleus accumbens induced a dose-dependent hyperactivity following pretreatment with nialamide (100 mg/kg, i.p., 2 hr). The hyperactivity induced by 10 micrograms of dopamine was antagonized by the i.p. administration of Y-516 (0.5-1.0 mg/kg), CCP (5-25 mg/kg), HPD (0.05-0.5 mg/kg) and CPZ (1-5 mg/kg) in a dose-dependent manner. The ED50 values of Y-516, CCP, HPD and CPZ were 0.85, 16.5, 0.098 and 2.53 mg/kg, respectively. These results suggest that Y-516 has a potential inhibitory effect on the mesolimbic dopaminergic system and may be a beneficial neuroleptic drugs.