Radioreceptorassay Of Opioid Peptides With ³H-Methionine Enkephalin And A Canine Limbic System Receptor Preparation

A radioreceptor assay (RRA) method is described to detect opioid peptides that uses a canine limbic system P₂ receptor preparation and ³H-methionine enkephalin as the displaced ligand. In our laboratory, ³H-ME is a useful probe to detect the presence of, and to facilitate the description of, opioid peptides in biological extracts. Those opioid receptor-active peaks are then studied subsequently in greater detail with immunoassay and mass spectrometry methods. A variety of peptide ligands including leucine enkephalin, beta-endorphin, Tyr-D-Ala-GIy-NMe-Phe-Gly-OL (“DAGO”), Tyr-D-Ser-Gly-Phe-Leu-Thr (“delta-receptor peptide”), and several dynorphins (1–7, 1–8, 1–9, 1–10, 1–17, and B) were used to further characterize the molecular specificity of that RRA system.