Substance Withdrawal SyndromeOpioid-Related DisordersNarcotic AntagonistsMorphine DependenceAnalgesics, OpioidMitragynaNaloxoneReceptors, Opioid, muNarcoticsMorphineReceptors, OpioidNaltrexoneBuprenorphineOpiate Substitution TreatmentMethadoneMethadyl AcetateReceptors, Opioid, deltaClonidineReceptors, Opioid, kappaPeriaqueductal GrayHeroin DependenceDrug ToleranceOpioid PeptidesDose-Response Relationship, DrugAdrenergic alpha-AgonistsBehavior, AnimalDrug InteractionsRats, Sprague-DawleyAlcohol Withdrawal DeliriumAlcohol Withdrawal SeizuresEnkephalinsEnkephalin, Ala(2)-MePhe(4)-Gly(5)-DynorphinsEnkephalin, D-Penicillamine (2,5)-EndorphinsEnkephalin, LeucinePainEnkephalin, Leucine-2-AlanineAnalgesicsDiprenorphinePain Measurementbeta-EndorphinBenzeneacetamidesEthanolMorphinansFentanylHeroinWithholding TreatmentHydromorphoneAnalgesiaBenzomorphansPyrrolidinesTime FactorsHyperalgesiaPain ThresholdCentral Nervous System DepressantsNicotineInjections, SpinalChronic PainAlcoholismSelf StimulationCocaineButorphanolPrescription Drug MisuseNucleus AccumbensLevorphanolTobacco Use DisorderRats, WistarBehavior, AddictiveMorphine DerivativesPrescription DrugsNeonatal Abstinence SyndromeConditioning, OperantPain, IntractableOligopeptidesDrug Administration ScheduleDiterpenes, ClerodaneAnalgesics, Non-NarcoticPiperidinesOxymorphoneAnalysis of VarianceMecamylamineProduct Recalls and WithdrawalsBrainEthylketocyclazocineDrug OverdoseMotor ActivityCocaine-Related DisordersDouble-Blind MethodNociceptorsLocus Coeruleus