Short communicationIntracerebroventricular injection of orexin-2 receptor antagonist promotes REM sleep

Orexins are important regulators of sleep-wakefulness (S-W). Rats were intracerebroventricularly (ICV)2 administered selective orexin-2 receptor antagonist, TCS-OX2-293. There was decreased wakefulness due to a decrease in the average wake episode duration and an increased REM sleep4 due to an increase in the number of REM episodes, indicating an inhibitory role of the central orexin-2 receptors on REM sleep generation.

► ICV injection of OX2R antagonist increased total sleep time and REM sleep. ► Increase in REM sleep was due to an increase in the number of REM episodes. ► Decrease in wakefulness was due to a decrease in the duration of wake episodes. ► Central OX2Rs exert an inhibitory control on REM sleep generation.