Blockade of both D1- and D2-dopamine receptors inhibits amphetamine-induced ascorbate release in the neostriatum.

In vivo recordings with electrochemically modified microvoltammetric electrodes revealed that several neuroleptic drugs, including haloperidol, clozapine, and thioridazine, blocked the rise in extracellular ascorbate produced by amphetamine in the neostriatum of urethane-anesthetized rats. This effect was also observed in animals that received a combined injection of Sch-23390 and sulpiride, but not when either of these drugs were administered alone or in combination with the 5-HT2 blocker, ritanserin. These results indicate that a combined blockade of D1- and D2-dopamine receptors blocks amphetamine-induced ascorbate release.