Dopamine D1 and D2 antagonists block L-DOPA-induced air-stepping in decerebrate neonatal rats.

L-DOPA administered to neonatal rats suspended in air elicits stereotypic locomotor activation termed air-stepping; it can be dose-dependently blocked by a dopamine (DA) D1 or D2 antagonist. In order to determine whether the forebrain is the site for this blockade, decerebrate 5-day-old rats were pretreated subcutaneously with either the DA D1 receptor antagonist SCH 23390 (16 mg/kg), the DA D2 receptor antagonist spiperone (6 mg/kg), or vehicle before receiving 100 mg/kg L-DOPA. Both antagonists blocked L-DOPA-induced air-stepping in both decerebrate and intact pups.