THE RELATIVE EFFECTS OF SELECTIVE M(1)-MUSCARINIC ANTAGONISTS ON RAPID EYE-MOVEMENT SLEEP

Three muscarinic antagonists, scopolamine, trihexyphenidyl and biperid en were systemically administered (0, 0.5, 1, 2 and 4 mg/kg) in rats. Scopolamine increased wakefulness and deceased sleep, both slow wave a nd REM. Trihexyphenidyl increased wakefulness and decreased REM sleep while biperiden decreased REM sleep selectively. The rank order REM-su ppressing effect was roughly scopolamine and trihexyphenidyl having a greater suppressing effect than biperiden. These results suggests that the regulation of the sleep-wake cycle is at least partially controll ed by the M1 muscarinic receptor.