Differential modulation of dopamine D 2 receptors by chronic haloperidol, nitrendipine, and pimozide

Abstract

Chronic administration of the neuroleptic haloperidol, the calcium channel antagonist nitrendipine, and the calcium channel antagonist neuroleptic pimozide produce differential effects on rat striatal 3H-spiperone binding. Following 7 days of 10 mg/kg i.p. administration, haloperidol significantly increases ( p< 0.01) dopamine D 2 receptor binding to 123% ± 6% of control values, whereas pimozide treatment significantly reduces ( p < 0.001) striatal 3H-spiperone binding to 46% ± 6% of control values. Chronic administration of the calcium channel antagonist nitrendipine does not alter 3H -spiperone binding relative to control values. Saturation analysis reveals an increase in B max following chronic haloperidol and a decrease in B max following chronic pimozide treatment. No alterations in muscarinic cholinergic sites, dopamine uptake sites, or calcium channel antagonist sites result following chronic drug administration. These results are the first demonstration of a decrease in dopamine D 2 binding sites after chronic neuroleptic treatment .