In 1957 Otto SCHAUMANN, one of the pionieers in pharmacological research on morphine and the first to prepare synthetic opiates, presented a mono graph entitled "Morphin und morphiniihnliche Verbindungen" as Volume 12 of the Handbook of Experimental Pharmacology. Now, 35 years later, we are publishing in the same series a new comprehensive volume covering the present status of opioid research. Since that time the topic has expanded enormously. The identification of opioid receptors and the detection of their endogenous ligands were landmarks which opened a new era in opioid research and fertilized the entire field of neurobiology. The rapid develop ment of this field is illustrated in the figure, which represents the number of papers published on opioid research since 1970 (searches performed on the MEDLINE data base). 3000 Vl

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.