Inhibitory role of D-1 dopamine receptors for the jerks induced by B-HT 920 in rats.

Jerks of the head and upper trunk produced by the dopamine agonist B-HT 920 in reserpine-treated rats were abolished by the D-1 dopamine receptor agonist SKF 38393. The combined treatment with SKF 38393 and B-HT 920 instead resulted in stereotypies and locomotion. B-HT 920 also caused jerks when given after the D-1 receptor antagonist SCH 23390 to rats not pretreated with reserpine. The results indicate that B-HT 920 induces jerks by stimulation of postsynaptic D-2-like dopamine receptors provided that the D-1 receptors are not activated.