Opposing actions of D-1 and D-2 dopamine receptor-mediated alterations of adenosine-3?,5?-cyclic monophosphate (cyclic AMP) formation during the amphetamine-induced release of endogenous dopamine in vitro

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Abstract
Changes in the formation of cyclic AMP following d-amphetamine (0.1 to 20 pmol/1) were examined in vitro in striatal slices of the rat. d-Amphetamine caused a doserelated increase in cyclic AMP content. This action of d-amphetamine was abolished by tissue pretreatment with reserpine (2.5 mg/kg, i.p.) and 3-iodotyrosine (1 mmol/1). By contrast, both clorgyline (0.1 pmol/l) and nomifensine (30 μmol/l) enhanced the d-amphetamine-induced increase in cyclic AMP formation. In superfusion experiments, a strong correlation between endogenous dopamine and cyclic AMP release was observed before, during and after d-amphetamine exposure. Finally, Sch 23390 (10 μmol/1) abolished while (−)sulpiride (10 μmol/1) enhanced the amphetamine-induced increase in cyclic AMP content. These results suggest that d-amphetamine enhances the formation of cyclic AMP through the release of endogenous dopamine into the synapse where it can interact with both D-1 and D-2 dopamine receptors. These results provide direct evidence that the antagonistic properties of D-1 and D-2 receptors on cyclic AMP formation are apparent at striatal synapses during release of endogenous neuronal dopamine.