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-NarcoticPainDose-Response Relationship, DrugBuprenorphineDrug ToleranceRats, Sprague-DawleyFentanylCHO CellsPain MeasurementLevorphanolChromatography, AffinityGuinea PigsBenzylidene CompoundsCricetinaeAnalgesiaMolecular Sequence DataOligopeptidesLigandsBinding, CompetitiveRadioligand AssayMorphine DerivativesGuanosine 5'-O-(3-Thiotriphosphate)HeroinAmino Acid SequenceMethadoneEnkephalin, MethionineProtein BindingSubstance Withdrawal SyndromeKineticsBinding SitesInjections, SpinalMorphine DependenceHydromorphoneCell LinePeriaqueductal GrayBase SequenceStructure-Activity RelationshipAntibody AffinityLoperamideSomatostatinPain ThresholdHyperalgesiaDrug InteractionsAffinity LabelsBrainSalviaImmunoglobulin Light ChainsNF-kappa BNociceptorsCricetulusSpinal CordInjections, IntraventricularRats, WistarAzocinesOpiate AlkaloidsSpiro CompoundsHeroin DependencePiperidinesBehavior, AnimalD-Ala(2),MePhe(4),Met(0)-ol-enkephalinRecombinant ProteinsTime FactorsNalbuphineGene Rearrangement, B-Lymphocyte, Light ChainChronic PainImmunoglobulin lambda-ChainsDihydromorphine