Effects of thioridazine on apomorphine-elicited stereotypic behavior and motor activity

Bilaterally injected thioridazine (10 micrograms) into the striata of rats augmented the stereotypic behavior elicited by apomorphine. The enhancing effect was attenuated by pretreatment with alpha-methyl-p-tyrosine. At 48 hr postinjection of thioridazine (1.0 mg/kg, IP), motor suppression from a low dose of apomorphine (0.2 mg/kg, IP) was enhanced; however, motor response to a high dose of apomorphine (1 mg/kg, SC) was not affected. Possible mechanisms of action of thioridazine are discussed.