MethadoneEnkephalinsEnkephalin, Ala(2)-MePhe(4)-Gly(5)-Enkephalin, LeucineEnkephalin, MethionineEnkephalin, D-Penicillamine (2,5)-Enkephalin, Leucine-2-AlanineNarcoticsReceptors, Opioid, muEndorphinsReceptors, OpioidReceptors, Opioid, deltaOpiate Substitution TreatmentReceptors, Neurokinin-3Opioid-Related DisordersAnalgesics, OpioidNaloxoneHeroin DependenceReceptors, Opioid, kappaNarcotic AntagonistsNeurokinin BEthylketocyclazocinePurinergic P1 Receptor AgonistsReceptors, TachykininMorphineTachykininsCyclazocineSerotonin Receptor AgonistsDopamine AgonistsDose-Response Relationship, DrugD-Ala(2),MePhe(4),Met(0)-ol-enkephalinMethadyl AcetateSubstance PBuprenorphineSerotonin 5-HT1 Receptor AgonistsNeurokinin AReceptors, Neurokinin-2PyrrolidinesSerotonin 5-HT2 Receptor AgonistsAdenosine A1 Receptor AgonistsNaltrexoneDynorphinsHeroinNeonatal Abstinence SyndromeRats, Sprague-DawleyBenzeneacetamidesGABA AgonistsAdenosine A2 Receptor AgonistsGuinea PigsGABA-A Receptor AgonistsGABA-B Receptor AgonistsCannabinoid Receptor AgonistsBenzomorphansSerotonin 5-HT4 Receptor AgonistsPiperidinesDiprenorphineOpioid PeptidesPurinergic P2 Receptor AgonistsRNA, Transfer, GlyDrug InteractionsAdrenergic alpha-2 Receptor AgonistsNeurokinin-1 Receptor AntagonistsOligopeptidesAnalgesicsAdenosine A3 Receptor AgonistsHistamine AgonistsCarboxypeptidase Hbeta-EndorphinEtorphineMuscarinic AgonistsAdenosineReceptors, Dopamine D2GlycineRadioligand AssayReceptors, Neurokinin-1Substance Withdrawal SyndromeMorphinansSubstance Abuse DetectionSerotonin AntagonistsBaclofenRats, Wistar2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepineNicotinic AgonistsAdrenergic beta-3 Receptor AgonistsAmino Acid SequencePhenethylaminesReceptors, Dopamine D1Drug ToleranceAdrenergic AgonistsPeptide FragmentsNeuronsReceptors, Purinergic P1KineticsBehavior, AnimalQuinpiroleMolecular Sequence DataPainExcitatory Amino Acid AgonistsBrainBinding, Competitive