Section A: Opioid Receptors/Multiplicity.- 1 Opioid Receptor Multiplicity: Isolation, Purification, and Chemical Characterization of Binding Sites.- 2 Expression Cloning of cDNA Encoding a Putative Opioid Receptor.- 3 Characterization of Opioid-Binding Proteins and Other Molecules Related to Opioid Function.- 4 Use of Organ Systems for Opioid Bioassay.- 5 Anatomical Distribution of Opioid Receptors in Mammalians: An Overview.- 6 Opioid Receptor Regulation.- 7 Multiple Opioid Receptors and Presynaptic Modulation of Neurotransmitter Release in the Brain.- 8 Opioid Receptor-G Protein Interactions: Acute and Chronic Effects of Opioids.- 9 Opioid Receptor-Coupled Second Messenger Systems.- 10 Allosteric Coupling Among Opioid Receptors: Evidence for an Opioid Receptor Complex.- Section B: Chemistry of Opioids with Alkaloid Structure.- 11 Chemistry of Nonpeptide Opioids.- 12 Selective Nonpeptide Opioid Antagonists.- 13 Presence of Endogenous Opiate Alkaloids in Mammalian Tissues.- Section C: Opioid Peptides.- 14 Regulation of Opioid Peptide Gene Expression.- 15 Regulation of Pituitary Proopiomelanocortin Gene Expression.- 16 Molecular Mechanisms in Proenkephalin Gene Regulation.- 17 Proopiomelanocortin Biosynthesis, Processing and Secretion: Functional Implications.- 18 Biosynthesis of Enkephalins and Proenkephalin-Derived Peptides.- 19 Prodynorphin Biosynthesis and Posttranslational Processing.- 20 Anatomy and Function of the Endogenous Opioid Systems.- 21 Atypical Opioid Peptides.- 22 Opioid Peptide Processing Enzymes.- 23 Peptidase Inactivation of Enkephalins: Design of Inhibitors and Biochemical, Pharmacological and Clinical Applications.- 24 Coexistence of Opioid Peptides with Other Neurotransmitters.- 25 Interrelationships of Opioid, Dopaminergic, Cholinergic and GABAergic Pathways in the Central Nervous System.- 26 Selectivity of Ligands for Opioid Receptors.- 27 Development of Receptor-Selective Opioid Peptide Analogs as Pharmacologic Tools and as Potential Drugs.- 28 Ontogeny of Mammalian Opioid Systems.- Section D: Neurophysiology.- 29 Opioids and Sensory Processing in the Central Nervous System.- 30 Opioid Actions on Membrane Ion Channels.