Dopaminergic Behaviour Stereospecific Promoted by the D1 Agonist R-SK & F 38393 and Selectively Blocked by the D1 Antagonist SCH 23390

The selective D1 dopamine receptor agonist R-SK & F 38393 (20 mg/kg), but not its S- antipode , stereospecifically promoted episodes of prominent grooming behaviour. Typical stereotyped behaviour, such at that induced by apomorphine, was not seen. Grooming responses to 20 mg/kg R-SK & F 38393 were blocked by 0.1-0.5 mg/kg of the selective D1 antagonist SCH 23390 but not by 1.0-5.0 mg/kg of the selective D2 antagonist metoclopramide, while stereotyped behaviour induced by 0.5 mg/kg apomorphine was blocked by both antagonists. These results are consistent with certain individual dopaminergic behaviours such as grooming being mediated by D1 receptors. Other dopaminergic syndromes may involve complex functional interactions between D1 and D2 receptors.