The involvement of D1 and D2 dopamine receptors in amphetamine-induced changes in striatal unit activity in behaving rats.

Selective D1 (SCH-23390) and D2 (eticlopride and sulpiride) dopamine receptor antagonists were assessed for their ability to reverse the effects of 1.0 mg/kg D-amphetamine on excitatory motor-related neurons in the striatum of freely moving rats. SCH-23390 (0.125, 0.25, 0.5 and 1.0 mg/kg) rapidly and consistently blocked amphetamine-induced neuronal excitations as did eticlopride (0.25 and 1.0 mg/kg). In contrast, (-)-sulpiride (10, 20 and 40 mg/kg) failed to alter the neuronal response to amphetamine. Similarly, SCH-23390 and eticlopride also blocked the behavioral effects of amphetamine, but sulpiride did not. Collectively, these results support the involvement of D1 and D2 dopamine receptors in the excitatory effects of amphetamine on striatal neurons, but suggest caution in assessing the neuronal and behavioral effects of sulpiride.