REGULATION OF PREFRONTAL CORTICAL DOPAMINE RELEASE BY DOPAMINE-RECEPTOR AGONISTS AND ANTAGONISTS

The effect of dopamine D1 and D2 receptors agonists and antagonists on extracellular dopamine release was evaluated by microdialysis in the prefrontal cortex. Nomifensine (5 muM) was included in the Ringer solution during the experiments. Cortical dopamine release was tetrodotoxin- and calcium-dependent and was stimulated by high potassium (60 mM) Ringer solution. 1-Methyl-4-phenylpyridinium ion (MPP+) (10 mM) increased the extracellular output of dopamine. SKF-38393 decreased the release of dopamine in a dose-related manner to about 80, 40 and 0% of the control values at 0.1, 1 and 10 muM, respectively. The decrease produced by SKF-38393 (10 muM) was partially antagonized by SCH-23390 at a concentration of 1 muM. Perfusion of CY-208243 (10 muM) produced a decrease in the release of dopamine to about 70% of controls. Quinpirole, at a concentration of 10 muM, produced a decrease in the release of dopamine to about 65% of controls. SCH-23390 and sulpiride, at 10 muM, increased the extracellular output of dopamine to about 150% of controls. These results indicate that dopamine D1 and D2 receptors are implicated in the autoregulation of dopamine release in the prefrontal cortex.