Anomalous behavioral response to imidazoleacetic acid, a GABA agonist, in animals treated chronically with...

Short-term haloperidol treatment decreases the stimulant effects of drugs with dopaminelike actions, while withdrawal from long-term haloperidol treatment enhances the effects of such drugs. In the present study, we have shown that withdrawal from long-term haloperidol treatment decreases or eliminates the tendency for imidazole-4-acetic acid, a GABA agonist, to decrease the locomotor activity of mice. Acute haloperidol treatment did not duplicate these effects. It is suggested that chronic administration of haloperidol causes changes in a variety of systems in the brain, and that the GABA system in particular is profoundly altered by such treatment.