Behavioral effects of dynorphin -- a novel opioid neuropeptide.

Adult male Swiss-kebster mice were implanted with permanently inawelling cannul ae with tips within the lateral cerebral ventricle. The neuropeptide dynorphin was infused centrally and subjects were tested on a variety of behavioral tasks. Peptide treated mice were more likely than vehicle treated mice to eat and groom. At higher doses, dynorphin treated mice showed barrel rotation which was occasionally succeeded by death. Effects upon behavior were only partially reversible by naloxone.