Neuropeptide Y reverses corticotropin-releasing hormone- and psychological stress-caused shortening of sodium pentobarbital-induced sleep in rats

Intracerebroventricular injection of neuropeptide Y (NPY) prolonged sodium pentobarbital (PbNa)-induced sleep in rats. The prolongation of PbNa-induced sleep by NPY was blocked by naloxone. Both corticotropin-releasing hormone and psychological stress caused shortening of PbNa-induced sleep, and the shortening was reversed by NPY. These results suggest that NPY has a sedative action and that an opioid system in the brain mediates at least in part the action of NPY.