Pituitary adenylate cyclase activating polypeptide enhances rapid eye movement sleep in rats

Pituitary adenylate cyclase activating polypeptide (PACAP), a member of the vasoactive intestinal polypeptide family, was tested for its effects on sleep in adult male Sprague-Dawley rats. PACAP was injected via intracerebro-ventricular cannula at light or dark onset; sleep and brain temperature (Tbr) were recorded for 12 h after injection. Rapid eye movement sleep (REMS) was significantly enhanced by 30 pmol, but not 3 or 300 pmol PACAP injected at dark onset. Non-REMS was not influenced by 3, 30, or 300 pmol PACAP Sleep and Tbr were not influenced by 3 or 30 pmol PACAP injected at light onset.