The Role of Dopaminergic System in Motor Coordination

Abstract

Previous studies have demonstrated that dopamine (DA) receptor agonists enhanced locomotor activity. The present study was designed to determine the relative contribution of D<inf>1</inf> and D<inf>2</inf> (DA) receptor subtypes in motor coordination. Apomorphine, a nonselective dopamine receptor agonist. decreased motor coordination at the doses of 0.125 and 0.25 mg/kg, but increased the motor coordination at 0.5 and 1 mg/kg. The D2 dopamine receptor antagonists, sulpiride (50 mg/kg) and spiperone (40 μg/kg). decreased motor coordination when administrered either alone or combination with apomorphine (0.5 mg/kg). Selective D<inf>1</inf> receptor agonist SKF 81297 (10 mg/kg) enhanced motor coordination. The effect of SKF 81297 was antagonized by fluphenazine (0.125 mg/kg). The D<inf>2</inf> receptor agonist bromocriptine (5. 10, 20.30 mg/kg) significantly increased motor coordination. The effect of bromocriptine (10 mg/kg) was inhibited when administered either sulpirid (50 mg/kg) or α-methyl p-tyrosine prior to bromocriptine. These data demonstrated that both D<inf>1</inf> and D<inf>2</inf> receptors may involved in motor coordination.