Dopamine agonists potentiate antiakinetic effects of competitive NMDA-antagonists in monoamine-depleted mice

The competitive NMDA-antagonists SDZ EAA-494 and CGP 37849 and the mixed D-1/D-2 dopamine agonists CI 201-678 and SDZ 205-152 reverse akinesia in monoamine-depleted mice in a dose dependent manner. Combination of threshold doses of NMDA-antagonists with dopamine agonists markedly enhances anti-akinetic effects. CI 201-678 which in addition to D-1 and D-2 receptors stimulates alpha-2 receptors produces a stronger effect than SDZ 205-152 which is devoid of alpha-2 agonist activity. The results indicate that concomitant blockade of NMDA-receptors and activation of dopamine receptors results in synergistic or at least additive motor stimulatory effects.