Chronic Treatment With Aripiprazole Prevents Development of Dopamine Supersensitivity and Potentially Supersensitivity Psychosis

BACKGROUND Long-term treatment of schizophrenia with antipsychotics is crucial for relapse prevention, but a prolonged blockade of D(2) dopamine receptors may lead to the development of supersensitivity psychosis. We investigated the chronic effects of aripiprazole (ARI) on dopamine sensitivity. METHODS We administered ARI (1.5 mg/kg/d), haloperidol (HAL; 0.75 mg/kg/d), or vehicle (VEH) via minipump for 14 days to drug-naive rats or to rats pretreated with HAL (0.75 mg/kg/d) or VEH via minipump for 14 days. On the seventh day following treatment cessation, we examined the effects of the treatment conditions on the locomotor response to methamphetamine and on striatal D(2) receptor density (N = 4-10/condition/experiment). RESULTS Chronic treatment with HAL led to significant increases in locomotor response and D(2) receptor density, compared with the effects of chronic treatment with either VEH or ARI; there were no significant differences in either locomotor response or D(2) density between the VEH- and ARI-treated groups. We also investigated the effects of chronic treatment with HAL, ARI, or VEH preceded by HAL or VEH treatment on locomotor response and D(2) density. ANOVA analysis indicated that the rank ordering of groups for both locomotor response and D(2) density was HAL-HAL > HAL-VEH > HAL-ARI > VEH-VEH. CONCLUSIONS Chronic treatment with ARI prevents development of dopamine supersensitivity and potentially supersensitivity psychosis, suggesting that by reducing excessive sensitivity to dopamine and by stabilizing sensitivity for an extended period of time, ARI may be helpful for some patients with treatment-resistant schizophrenia.