Exploration of novel radioiodine‐labeling techniques for opioid peptides

Abstract

A vast number of opioid peptides are derived from processing of precursors from three separate genes. The prodynorphin gene generates dynorphin A, the predominant product and the natural ligand for the kappa1 opioid receptor. However, other products of this gene have also been identified, including dynorphin B and α‐neoendorphin. Studies of kappa receptors have utilized 3H‐U69,593, a highly selective drug with poor affinity for both mu and delta opioid receptors. However, evidence suggests that 3H‐U69,593 may be labeling more than one class of kappa receptor in brain tissue. Further exploration of these binding sites requires the development of novel radioligands. In an effort to further the characterization of these potential kappa receptor subtypes, we have developed 125I‐labeled opioid peptides with high affinity and established receptor binding assays for them. Funded by grants to GWP (DA0641, DA07242, DA02615 and DA00220) and a training grant to JEP (DA07274) from the National Insitute on Drug Abuse.