CocaineHeroinEuphoriaFlupenthixolHeroin DependenceAzocinesCocaine-Related DisordersSelf AdministrationDopamine Uptake InhibitorsNarcoticsCrack CocaineMethadoneMorphine DerivativesConditioning, OperantBehavior, AddictiveNucleus AccumbensReinforcement (Psychology)Street DrugsSubstance Withdrawal SyndromeSubstance Abuse DetectionReinforcement ScheduleBehavior, AnimalBuprenorphineDrug OverdoseDrug-Seeking BehaviorSubstance-Related DisordersExtinction, PsychologicalDose-Response Relationship, DrugOpioid-Related DisordersCodeineSubstance Abuse, IntravenousRewardRats, Sprague-DawleyDopamineMotor ActivityDopamine Plasma Membrane Transport ProteinsNaltrexoneDopamine AntagonistsMorphineOpiate Substitution TreatmentRats, Long-EvansCuesReceptors, Opioid, muDopamine AgonistsBenztropineDrug and Narcotic ControlNaloxoneDrug UsersGas Chromatography-Mass SpectrometryConditioning (Psychology)Ventral Tegmental AreaReceptors, Dopamine D2Analgesics, OpioidButyrylcholinesteraseDrug InteractionsCrimeMicrodialysisInjections, IntravenousAnalysis of VarianceTime FactorsMacaca mulattaSaimiriSubstance Abuse Treatment CentersCorpus StriatumMotivationDrug ContaminationMethamphetamineBenzazepinesChoice BehaviorPrenatal Exposure Delayed EffectsReceptors, Dopamine D3Receptors, Opioid, kappaAmphetamineBrainDextroamphetamineQuinpiroleDiscrimination LearningSweat