3 priming sessions with the D1R agonist SKF81297 (0.8 mg/kg, s.c.) induce AIMs in rats with established L-DOPA-induced-AIMs. (A) Mean LAO AIMs at the 3 priming sessions using SKF81297. (B) Mean locomotor AIMs elicited by SKF81297. (C) The D1R agonist-induced LAO AIMs were blocked by the D1R antagonist SCH23390. (D) The D1R agonist-induced locomotor AIMs were also blocked by the D1R antagonist SCH23390. MK-801 (0.3 mg/kg) worsens D1R agonist-induced LAO AIMs. In (E) mean LAO AIMs are shown. (F) The graph depicts mean locomotor AIMs, and shows no effect of MK-801 to either block locomotor AIMS or induce ipsiversive AIMs. In (G and H) mean choreiform limb, orolingual and dystonic axial AIMs are depicted separately, showing the effect of MK-801 is predominantly on dystonic AIMs, and to lesser extent on orolingual AIMs. All graphs show the mean data ±SEM acquired after injection of drugs. Significant differences from vehicle control experiments in the same testing sessions are depicted by asterisks, ***p < 0.001, *p < 0.05 (n = 7–9; two-tailed t-tests).