REM sleep rebound after its suppression by vasotocin in cats.

Extremely small amounts (10(-4) pg) of synthetic arginine vasotocin (AVT) injected into the pineal recess of unanesthetized cats induced a continuous NREM sleep for about 60 minute and completely suppressed REM sleep for about 5 hours. The reappearance of the REM sleep following AVT administration occurred with a marked rebound, lasting for more than one hour. Since neither vasopressin nor oxytocin, at the same doses, were able to affect significantly the REM sleep, it is concluded that AVT is specifically involved in the modulation and/or circadian organization of the REM sleep.