The dopamine D1 receptor agonists, A68930 and SKF 38393, induce arousal and suppress REM sleep in the rat

Abstract

The effects of the dopamine D1 receptor full agonist, A68930, on sleep-wake patterns and grooming behaviour were studied in the rat. The partial dopamine D1 receptor agonist, SKF 38393, was used for comparison. A68930 (0.003-0.3 mg/kg s.c.) increased waking time, reduced the amount of rapid eye movement (REM) sleep and enhanced spontaneous grooming dose dependently. The ED50 were 0.06, 0.02 and 0.05 mg/kg, respectively. The D1 antagonist, SCH 23390 (0.003 mg/kg s.c.), blocked the effects of A68930 on wakefulness and grooming but not those on REM sleep. SKF 38393 (0.1-10 mg/kg s.c.) increased grooming with an ED50 of 1.4 mg/kg and a dose-response relationship similar to that of A68930 (potency ratio 28). Conversely, the increase of wakefulness and reduction of REM sleep caused by SKF 38393 had dose-response curves different from those of A68930. The results support the view that D1 receptors may have a physiological function in producing arousal.