Stimulus-evoked dopamine overflow in the rat nucleus accumbens is decreased following chronic haloperidol administration: an in vivo voltammetric study.

Fast cyclic voltammetry was used to investigate the effects of chronic haloperidol (HAL) treatment on electrically evoked dopamine (DA) overflow in the nucleus accumbens of the anaesthetized rat in vivo. Evoked DA efflux was significantly reduced in rats treated with 1.0 mg/kg per day HAL for 21 days. In rats treated with 0.5 mg/kg per day, evoked DA overflow was reduced, but did not differ significantly from control values. In untreated animals, injection of a single dose of HAL resulted in a significant increase in the DA overflow evoked by subsequent stimulus trains. In contrast, this HAL challenge did not produce a significant enhancement in evoked DA overflow in any of the HAL-treated groups. These results are consistent with the previous reports that basal DA release is reduced after chronic HAL treatment, and show for the first time that chronic HAL administration decreases stimulus-evoked DA overflow in the rat nucleus accumbens in vivo.