EnkephalinsEnkephalin, MethionineEnkephalin, LeucineMorphineEnkephalin, Ala(2)-MePhe(4)-Gly(5)-Enkephalin, Leucine-2-AlanineEnkephalin, D-Penicillamine (2,5)-EndorphinsReceptors, Opioid, muReceptors, OpioidNaloxoneReceptors, Opioid, deltaAnalgesics, OpioidMorphine DerivativesMorphine DependenceEthylketocyclazocineNarcotic AntagonistsCyclazocineReceptors, Neurokinin-3NarcoticsD-Ala(2),MePhe(4),Met(0)-ol-enkephalinReceptors, Opioid, kappaDynorphinsDrug ToleranceNeurokinin BNaltrexoneTachykininsReceptors, TachykininBenzomorphansSubstance PCarboxypeptidase Hbeta-EndorphinOpioid PeptidesAnalgesicsDiprenorphineNeurokinin AEtorphineInjections, SpinalMorphinansReceptors, Neurokinin-2Dose-Response Relationship, DrugOligopeptidesGuinea PigsAnalgesiaPain MeasurementThiorphanProtein PrecursorsRNA, Transfer, GlyRats, Sprague-DawleySubstance Withdrawal SyndromeNeprilysinTioproninPyrrolidinesAdrenal MedullaBenzeneacetamidesBrainPainIleumInjections, IntraventricularPeriaqueductal GraySomatostatinLocus CoeruleusFentanylChromaffin GranulesVas DeferensGlobus PallidusSpinal CordRats, Inbred StrainsGlycineNeurokinin-1 Receptor AntagonistsAmino Acid SequenceCodeineDihydromorphineKineticsNeuronsPain, PostoperativeBenzylidene CompoundsCorpus StriatumMolecular Sequence DataMyenteric PlexusBinding, CompetitiveBehavior, AnimalCarboxypeptidasesPeptide FragmentsPentazocineReceptors, Neurokinin-1Neurotransmitter AgentsPeptidesOxymorphoneElectric StimulationPiperidinesDrug InteractionsPain ThresholdNeuroblastomaBrain ChemistryProtease InhibitorsGalaninNociceptive PainStructure-Activity RelationshipGuanosine 5'-O-(3-Thiotriphosphate)