Chronic treatments with zotepine, thioridazine, and haloperidol affect apomorphine-elicited stereotypic behavior and striatal 3H-spiroperidol binding sites in the rat.

Apomorphine (AP)-elicited sterotypic behavior and striatal 3H-spiroperidol binding sites were studied in rats given 3 weeks of chronic treatment with one of the following neuroleptic drugs: zotepine (10 or 20 mg/kg/day IP); thioridazine (10 or 20 mg/kg/day IP); haloperidol (2 or 5 mg/kg/day IP). On days 10-12 after the chronic neuroleptic treatment, enhancement of AP-elicited stereotypy was seen in the high- and low-dose haloperidol-treated, as well as in the high-dose thioridazine and zotepine-treated rats when compared to that of saline-injected controls. No significant change in the response to AP was found in the low-dose thioridazine and zotepine-treated animals. Significant increases in the concentration of striatal 3H-spiroperidol binding sites were seen after treatment with all three neuroleptics, both high and low doses. A positive correlation was found between AP-elicited stereotypy and the concentration of striatal 3H-spiroperidol binding sites in the haloperidol-treated and control rats. However, no such correlation was seen after chronic thioridazine and zotepine treatments.