EnkephalinsEnkephalin, MethionineEnkephalin, LeucineEnkephalin, Ala(2)-MePhe(4)-Gly(5)-Enkephalin, Leucine-2-AlanineEnkephalin, D-Penicillamine (2,5)-EndorphinsReceptors, OpioidReceptors, Opioid, deltaReceptors, Opioid, muNaloxoneDynorphinsEthylketocyclazocineCyclazocineNarcotic AntagonistsMorphineCarboxypeptidase HBenzomorphansNaltrexoneRNA, Transfer, ProD-Ala(2),MePhe(4),Met(0)-ol-enkephalinbeta-EndorphinAnalgesics, OpioidReceptors, Opioid, kappaOpioid PeptidesDiprenorphineNarcoticsEtorphineThiorphanOligopeptidesProtein PrecursorsAnalgesicsMorphinansTioproninNeprilysinAdrenal MedullaPyrrolidinesProlineChromaffin GranulesBrainGlobus PallidusSomatostatinIleumDrug ToleranceGuinea PigsDihydromorphineVas DeferensSubstance PRats, Inbred StrainsAmino Acid SequenceCarboxypeptidasesInjections, IntraventricularRats, Sprague-DawleyCorpus StriatumBenzylidene CompoundsInjections, SpinalMyenteric PlexusLocus CoeruleusKineticsBinding, CompetitiveMolecular Sequence DataDose-Response Relationship, DrugNeuronsMorphine DerivativesNeurotransmitter AgentsPeptidesProtease InhibitorsNeuroblastomaChromaffin SystemNociceptive PainSpinal CordGalaninElectric StimulationSubstantia Gelatinosa