The dopamine D1 receptor is involved in the regulation of REM sleep in the rat.

The dopamine D1 receptor agonist, SKF 38393, and the D1 antagonist, SCH 23390, were studied for their effects on sleep in the rat. Over 6 h, SKF 38393 (0.1-10 mg/kg s.c.) dose dependently reduced the amount of rapid eye movement (REM) sleep and enhanced the duration of wakefulness. The drug affected REM at low doses (ED50 = 0.4 mg/kg) at which wakefulness was unchanged and the characteristic grooming behavior was not apparent. REM changes were characterized by a decrease in the number of episodes with no alteration of latency to the first episode. Over a very low dose range (0.003-0.3 mg/kg s.c.), SCH 23390 enhanced the amount of REM by increasing both number and average duration of episodes. There was also a moderate increase of non-REM sleep but the percent change was less marked than that occurring for REM. Given at 0.003 mg/kg, SCH 23390 prevented the REM changes induced by SKF 38393 (0.3-3 mg/kg). It is suggested that D1 receptors are involved in the regulation of the REM sleep process.