Effect of lateral cerebroventricular injection of the appetite-stimulating neuropeptide, orexin and neuropeptide Y, on the various behavioral activities of rats.

The effect of lateral cerebroventricular injection of the appetite-stimulating neuropeptide, orexin and neuropeptide Y (NPY), on the behavior of rats was investigated. An immediate increase in face washing activity was observed after injection of orexin A or orexin B, but not NPY. Orexin A had a more potent effect on face washing behavior than orexin B. Grooming and burrowing activities also increased significantly after injection of orexin A, whereas, orexin B significantly increased burrowing and searching behavior. Feeding behavior and food consumption increased dramatically within 10 min of injection of NPY. Although the significant increase in feeding behavior was also observed after injection of orexin A, total food intake did not change significantly. These results suggest that orexin may be involved in the regulation of several other behavioral activities in rats, besides feeding. Copyright 1999 Elsevier Science B.V.