Sensitivity of neuronal dopamine response in the substantia nigra and ventral tegmentum to clozapine, metoclopramide and SCH 23390.

The activity of neurones in the substantial nigra and ventral tegmentum was recorded extracellularly in vitro. Dopamine produced depression of spontaneous firing in a dose-dependent manner. Antagonism of these neuronal responses to dopamine by metoclopramide, SCH 23390 and clozapine was examined. Metoclopramide antagonised the responses to dopamine in the manner expected; SCH 23390 had little effect on the response to dopamine as would be predicted for a selective dopamine "D1" antagonist. Clozapine did not produce the expected antagonism of the response to dopamine. The results at the single neurone level are compared with behavioural and biochemical data.