Chronic haloperidol does not increase specific dopamine receptor binding in rat frontal cortex.

The specific D2 dopamine receptor antagonist sulpiride was used to quantitate the minor component of [3H]spiroperidol binding (at 0.1 nM) to dopamine receptors in rat frontal cortex. Chronic treatment of rats with haloperidol, 0.5 mg/kg for 3 weeks or 2.5 mg/kg for 5 weeks, did not alter the specific binding of [3H]spiroperidol to dopamine receptors in frontal cortex, whereas both treatments significantly increased binding to striatal dopamine receptors. These findings may be relevant to previous studies demonstrating that the frontal cortex, but not the striatum, is resistant to the development of tolerance to the dopamine metabolite-elevating effects of chronic neuroleptic treatment.