Narcotic AntagonistsNaltrexoneReceptors, OpioidReceptors, Opioid, muNaloxoneAnalgesics, OpioidReceptors, Opioid, deltaReceptors, Opioid, kappaOpioid PeptidesDose-Response Relationship, DrugEndorphinsMorphineNarcoticsPurinergic P2 Receptor AntagonistsEnkephalin, Ala(2)-MePhe(4)-Gly(5)-EnkephalinsRats, Sprague-DawleyDynorphinsPiperidinesStructure-Activity RelationshipEnkephalin, LeucineNicotinic AntagonistsDiprenorphineBinding, CompetitiveEnkephalin, D-Penicillamine (2,5)-MorphinansEnkephalin, Leucine-2-AlanineEnkephalin, MethionineAzocinesAnalgesicsBenzeneacetamidesOpioid-Related DisordersRadioligand Assaybeta-EndorphinBenzomorphansOligopeptidesPyrrolidinesGuinea PigsHormone AntagonistsConotoxinsSubstance Withdrawal SyndromePain MeasurementDopamine AntagonistsPainStereoisomerismNeurokinin-1 Receptor AntagonistsBuprenorphineExcitatory Amino Acid AntagonistsLigandsMorphine DependenceReceptors, SerotoninFentanylHistamine H2 AntagonistsReceptors, NicotinicOxymorphoneInterleukin 1 Receptor Antagonist ProteinLevorphanolDrug ToleranceViper VenomsBicyclo Compounds, HeterocyclicCHO CellsMuscarinic AntagonistsDrug InteractionsPeptides, CyclicHeroinBenzylidene CompoundsRats, WistarSulfonamidesInhibitory Concentration 50IndolesGABA AntagonistsInjections, IntraventricularCricetinaeHistamine H1 AntagonistsPurinergic P1 Receptor AntagonistsAnalgesiaEtorphineDrug Inverse AgonismMolecular StructurePeptide FragmentsInjections, SpinalAnalgesics, Non-NarcoticCell LineBehavior, AnimalDiterpenes, ClerodanePruritusAmino Acid SequenceHistamine AntagonistsMolecular Sequence DataMeptazinolSignal TransductionKineticsAdenosine A2 Receptor AntagonistsTetrahydroisoquinolinesProtein BindingAntipruriticsAdrenergic alpha-1 Receptor AntagonistsCells, CulturedCalciumSerotonin Antagonists