MorphineEnkephalinsEnkephalin, Ala(2)-MePhe(4)-Gly(5)-Enkephalin, MethionineEnkephalin, LeucineMorphine DependenceReceptors, Opioid, muAnalgesics, OpioidNarcoticsDrug ToleranceEnkephalin, D-Penicillamine (2,5)-NaloxoneEnkephalin, Leucine-2-AlanineNarcotic AntagonistsReceptors, OpioidReceptors, Opioid, deltaMorphine DerivativesSubstance Withdrawal SyndromeEndorphinsNaltrexoneRats, Sprague-DawleyLocus CoeruleusReceptors, Neurokinin-3LevallorphanDose-Response Relationship, DrugDopamine AgonistsPeriaqueductal GrayOpioid-Related DisordersTriptorelin PamoateLuteolytic AgentsArrestinsEthylketocyclazocineNeurokinin BOpioid PeptidesHydrocarbons, FluorinatedCyclazocineEtorphineTachykininsReceptors, Opioid, kappaPain MeasurementReceptors, TachykininAnalgesiaAdenylate CyclaseBuprenorphineGonadotropin-Releasing HormoneTime FactorsD-Ala(2),MePhe(4),Met(0)-ol-enkephalinNucleus AccumbensLeuprolidePainMethadoneCyclic AMPSubstance PMice, Inbred C57BLNeurokinin ABehavior, AnimalReceptors, Neurokinin-2QuinpiroleHyperalgesiaDynorphinsRNA, MessengerReceptors, Dopamine D2Orphan Nuclear ReceptorsNeuronsAdrenergic beta-AgonistsBrainSpinal CordSignal TransductionPPAR gammaReceptors, Adrenergic, beta-2Mice, KnockoutBenzomorphansAnalgesicsCyclic AMP-Dependent Protein KinasesPhosphorylationInjections, SpinalRats, WistarBenzeneacetamidesG Protein-Coupled Inwardly-Rectifying Potassium ChannelsDrug Administration ScheduleGene Expression RegulationGuinea PigsCell LineMotor ActivityRNA, Transfer, GlyReceptors, Dopamine D1Adrenergic beta-2 Receptor AgonistsMorphinansAmino Acid Sequencebeta-EndorphinMolecular Sequence DataCells, CulturedDiprenorphineThiazolidinedionesPPAR alphaCarboxypeptidase HGTP-Binding Protein beta SubunitsSynaptic TransmissionExcitatory Postsynaptic PotentialsReceptors, N-Methyl-D-Aspartate