Receptors, Opioid, muEnkephalin, Ala(2)-MePhe(4)-Gly(5)-MorphineAnalgesics, OpioidReceptors, Opioid, deltaNarcotic AntagonistsEtorphineDiprenorphineNaloxoneDrug ToleranceNaltrexoneBacteriophage muNarcoticsReceptors, Opioid, kappaReceptors, OpioidEnkephalin, D-Penicillamine (2,5)-Opioid PeptidesReceptors, OdorantFentanylEnkephalinsLocus CoeruleusChromomycin A3ArrestinsMorphine DependenceRNA PhagesMorphine DerivativesEnkephalin, MethionineAnalgesiaRats, Sprague-DawleyPeriaqueductal GrayAnalgesicsMorphinansOligopeptidesEndocytosisNociceptionGuanosine 5'-O-(3-Thiotriphosphate)Injections, SpinalPain MeasurementPosterior Horn CellsNeuronsDose-Response Relationship, DrugRadioligand AssaySomatostatinGene Knock-In TechniquesSalmonella Food PoisoningSpinal CordPainG-Protein-Coupled Receptor Kinase 3Molecular Sequence DataSubstance Withdrawal SyndromePruritusDynorphinsFerredoxin-NADP ReductaseCodeineG Protein-Coupled Inwardly-Rectifying Potassium ChannelsCHO CellsProtein BindingHEK293 CellsLuciferases, Renillabeta-EndorphinCorpus StriatumSignal TransductionOlfactory Receptor NeuronsCyclic AMPRNA, MessengerOxycodoneMethadoneMorganella morganiiNucleus AccumbensAcupuncture AnalgesiaPoly CCell LineBase SequenceStreptothricinsMice, KnockoutOpioid-Related DisordersTransfectionBrainDrug InteractionsArrestinRGS ProteinsCricetulusCricetinaePlicamycinProtein Transportrab4 GTP-Binding ProteinsMice, Inbred C57BLImmunoprecipitationReceptors, Neurokinin-1BuprenorphineSulfur RadioisotopesGTP-Binding Protein alpha Subunit, Gi2Promoter Regions, GeneticSp3 Transcription FactorGene Expression RegulationVentral Tegmental AreaSensory System AgentsAmino Acid SequenceHelix-Turn-Helix MotifsCytokinesis