A review of some nonopioid actions of dynorphin

The evidence for several sites of activity within the dynorphin sequence is reviewed. A number of endocrine and CNS peptides are believed to contain several sites of biological activity. Data from a number of laboratories is consistent with such a mechanism for the opioid peptide dynorphin. These findings stem from structure-activity studies in which nonopiate fragments of dynorphin sometimes show biological activity and from the failure of naloxone to reverse some effects of dynorphin. These results are discussed in terms of the possible physiological relevance of such nonopiate actions.