Electroencephalographic analysis of the sleep-inducing actions of cholecystokinin

Cortical EEG analysis of the effects of cholecystokinin (CCK) on sleep were performed in rats treated intraperitoneally with 1,10, or 20 micrograms/kg CCK8. Latency to the first episode of non-REM sleep was significantly reduced from 29 minutes to 16 minutes. No change in total waking time, total non-REM sleep, or total REM sleep was seen at any dose over the first hour after CCK administration. Locomotor activity was significantly reduced by 10 micrograms/kg CCK8 during the first ten minutes only. The temporal separation between the sleep-latency reduction and the behavioral inactivity induced by CCK indicate that these effects are distinguishable phenomena. Sleep does not appear to be a primary cause for the satiety-related behavioral effects of CCK.