Heroin DependenceMorphineMorphine DerivativesAmphetamineMethadoneNarcoticsHeroinAmphetaminesMorphine DependenceBuprenorphineReceptors, Opioid, muBehavior, AddictiveAnalgesics, OpioidNuclear Receptor Subfamily 4, Group A, Member 2Drug ToleranceCentral Nervous System StimulantsSubstance-Related DisordersNaloxoneSubstance Withdrawal SyndromeDextroamphetamineOpioid-Related DisordersNarcotic AntagonistsCocaineCryptochromesAmphetamine-Related DisordersMethamphetamineSelf AdministrationSubstance Abuse DetectionLinkage DisequilibriumNucleus AccumbensStreet DrugsCodeineBehavior, AnimalDopamineDose-Response Relationship, DrugRewardRats, Sprague-DawleyNaltrexoneDopamine Uptake InhibitorsGenetic Predisposition to DiseaseGene FrequencyAnalgesiaPain MeasurementConditioning, OperantGenetic TestingMotor ActivityReceptors, OpioidInjections, SpinalHaplotypesPainSubstance Abuse Treatment CentersAnalgesicsPolymorphism, Single NucleotidePain, PostoperativeOpiumGas Chromatography-Mass SpectrometryGenotypeTobacco Use DisorderN-Methyl-3,4-methylenedioxyamphetamineReinforcement (Psychology)Ventral Tegmental AreaDrug-Seeking BehaviorBrainHydromorphoneDrug InteractionsCorpus StriatumEnkephalinsConditioning (Psychology)Compulsive BehaviorDrug OverdoseNalorphineStereotyped BehaviorOxycodoneEnkephalin, Ala(2)-MePhe(4)-Gly(5)-Time FactorsNicotineReceptors, Opioid, deltaDopamine AgentsLimbic SystemAlcoholismOpiate Substitution TreatmentMotivationAnalgesia, Patient-ControlledImpulsive BehaviorDopamine AntagonistsDopamine Plasma Membrane Transport ProteinsDrug and Narcotic ControlReceptors, Dopamine D2Reinforcement ScheduleReceptors, Opioid, kappaFentanylAnalysis of VarianceMicrodialysisExtinction, PsychologicalDesigner Drugs3,4-MethylenedioxyamphetaminePeriaqueductal GrayDopamine AgonistsMorphinansEuphoria