Normalization by antipsychotic drugs of biochemically induced abnormal behavior in rats.

Male rats were trained to perform a conditioned avoidance response combined with a successive discrimination in a modified shuttle box. The administration of L-Dopa, 100 mg/kg i.p., after inhibition of peripheral aromatic amino acid decarboxylase, or apomorphine, 2 mg/kg i.p., was found to disrupt the discriminative but not the avoidance behavior. The dopamine receptor antagonist pimozide (0.5 mg/kg i.p.), but not the noradrenaline receptor antagonist phenoxybenzamine (10 or 20 mg/kg i.p.) completely antagonized the L-Dopa-induced abnormal behavior, indicating sn involvement of central dopamine mechanisms. The present data show that antipsychotic drugs not only inhibit behavior but can also improve behavior in animals with a disturbed function.