Weak antiparkinsonian activity of the D1 agonist C-APB (SKF 82958) and lack of synergism with a D2 agonist in primates.

The role of D1 receptors in motor control is poorly understood. In parkinsonian squirrel monkeys, the full D1 agonist C-APB (SKF 82958; 0.1-0.4 mg/kg s.c.) caused weak stimulation of locomotor activity. However, the motor stimulant effects of the D2 agonist (+)-PHNO (0.001 mg/kg s.c.) were not potentiated by C-APB (0.3 mg/kg). Differences between these observations and expectations from experiments using rodents are discussed.