Ex vivo 3H-spiroperidol binding to rat striatum and the inhibitory effects of neuroleptics.

Neuroleptic drugs were given to rats and at different time intervals the animals were decapitated and 3H-spiroperidol binding to the striatal homogenates was determined in vitro. Two hours after an intraperitoneal administration of spiroperidol, perphenazine, haloperidol, chlorpromazine or thioridazine in doses of 0.03-30 mg/kg, 3H-spiroperidol, binding to the striatal homogenates was inhibited dose-dependently with an ID50 value of 0.11, 0.23, 1.1, 3.7 or 9.4 mg/kg, respectively. After a single intramuscular administration of fluphenazine enanthate (10 mg/kg), a long-acting neuroleptic drug, long-lasting inhibitory effect (over 4 weeks) on the binding was also observed. These results indicate that ex vivo 3H-spiroperidol binding method may be useful to measure the duration and the potency of anti-dopaminergic activities of drugs.