Receptors, Opioid, kappaReceptors, OpioidReceptors, Opioid, muReceptors, Opioid, deltaAnalgesics, OpioidNarcotic AntagonistsDynorphinsNaltrexoneEnkephalinsEnkephalin, D-Penicillamine (2,5)-Enkephalin, Ala(2)-MePhe(4)-Gly(5)-NaloxoneOpioid PeptidesBenzeneacetamidesDiprenorphineMorphinansEthylketocyclazocinePyrrolidinesEnkephalin, LeucineEnkephalin, Leucine-2-AlanineNarcoticsBenzomorphansMorphineCyclazocineEndorphinsEtorphineButorphanolDiterpenes, ClerodaneAnalgesicsOpioid-Related Disordersbeta-EndorphinImmunoglobulin kappa-ChainsDynamin IAnalgesics, Non-NarcoticDose-Response Relationship, DrugBuprenorphinePainDrug ToleranceCHO CellsFentanylRats, Sprague-DawleyPain MeasurementLevorphanolChromatography, AffinityGuinea PigsBenzylidene CompoundsCricetinaeMolecular Sequence DataAnalgesiaOligopeptidesLigandsBinding, CompetitiveRadioligand AssayGuanosine 5'-O-(3-Thiotriphosphate)Morphine DerivativesAmino Acid SequenceHeroinEnkephalin, MethionineMethadoneProtein BindingSubstance Withdrawal SyndromeBinding SitesKineticsMorphine DependenceInjections, SpinalHydromorphoneCell LinePeriaqueductal GrayBase SequenceStructure-Activity RelationshipAntibody AffinityHyperalgesiaLoperamidePain ThresholdSomatostatinAffinity LabelsSalviaImmunoglobulin Light ChainsNF-kappa BNociceptorsBrainCricetulusSpinal CordOpiate AlkaloidsAzocinesDrug InteractionsSpiro CompoundsHeroin DependenceInjections, IntraventricularD-Ala(2),MePhe(4),Met(0)-ol-enkephalinGene Rearrangement, B-Lymphocyte, Light ChainNalbuphinePiperidinesBehavior, AnimalChronic PainImmunoglobulin lambda-ChainsRats, WistarDihydromorphineRecombinant ProteinsOpiate Substitution Treatment