[Regulation of (-)-sulpiride-induced increase in evoked dopamine release from striatal slices in rat]

The effects of dopamine (DA) agonist and antagonists on (-)-sulpiride-induced increase in electrically evoked DA release from striatal slices of rats were investigated. (-)-Sulpiride at concentrations of 10 nM to 1 microM in the superfusate caused a dose-dependent increase in electrically evoked DA release from the slices. (+)-Sulpiride had little effect on the evoked DA release up to 1 microM. Apomorphine inhibited the electrically evoked DA release which was antagonized by sulpiride. SCH 23390 and forskolin had no effect on the sulpiride-induced enhancement of evoked DA release. Pretreatment with the irreversible DA receptor antagonist, N-ethoxy-carbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ), caused a significant increase in evoked DA release and prevented the sulpiride-induced increase in evoked DA release. These results indicate that the sulpiride-induced increase in evoked DA release is due to an antagonism of the activation of DA autoreceptors by endogenously released DA.