Properties of receptors mediating opioid effects: discrimination of receptor types

Quantitative characterization of opioid receptor types is now feasible by several methods which examine different aspects of ligand interaction with receptor and the induction of agonist effect. Application of these approaches to opioid receptor classification, using receptor-type selective agonists and antagonists, should lead to the development of profiles of the properties of each type of receptor which will be useful in defining the receptors mediating opioid action in other systems.