Striatal enlargement in rats chronically treated with neuroleptic.

BACKGROUND Striatal enlargement with chronic neuroleptic treatment in schizophrenic patients has been reported by several investigators. Longitudinal magnetic resonance imaging studies of patients suggest that changes in striatal volume may be caused by treatment with antipsychotic medication. METHODS We have examined the effects of chronic neuroleptic treatment on postmortem striatal volume in the laboratory rat and have examined the relationship between striatal volume and vacuous chewing movements (VCMs). Autoradiographs of 50 rats treated with haloperidol (1.5 mg/kg/day) or drug free for varying durations of time (1-12 months) were utilized in this analysis. RESULTS Chronic treatment with neuroleptics (1 month or greater) was associated with larger striatal volumes. The increase in striatal volume was present at 1 month of treatment and was sustained to 12 months of treatment. Rats that developed the high-VCM syndrome had larger striatal volumes than both drug-free and low-VCM rats, while low-VCM rats had larger striatal volumes than drug-free rats. CONCLUSIONS These data suggest that chronic neuroleptic treatment is the cause of striatal enlargement in the laboratory rat, and that this enlargement is most prominent in rats that have the high-VCM syndrome.