PenicillamineEnkephalinsOpioid PeptidesEnkephalin, MethionineEnkephalin, LeucineEndorphinsReceptors, OpioidEnkephalin, Leucine-2-AlanineReceptors, Opioid, muEnkephalin, Ala(2)-MePhe(4)-Gly(5)-DynorphinsReceptors, Opioid, deltaEnkephalin, D-Penicillamine (2,5)-Gold Sodium ThiomalateNaloxoneAnalgesics, Opioidbeta-EndorphinPeptidesReceptors, Opioid, kappaHepatolenticular DegenerationNarcotic AntagonistsS-Nitroso-N-AcetylpenicillamineSulfasalazineNaltrexoneAurothioglucoseArthritis, RheumatoidD-Ala(2),MePhe(4),Met(0)-ol-enkephalinMorphineAuranofinTartratesNarcoticsOligopeptidesCystinuriaDimercaprolDrug EruptionsPeptide FragmentsChelating AgentsOrganogold CompoundsBlood SedimentationMorphinansAntimonyProtein PrecursorsDiprenorphineNitric Oxide DonorsSulfhydryl CompoundsEthylketocyclazocineBenzomorphansCarboxypeptidase HAnalgesicsAminopropionitrileDose-Response Relationship, DrugCopperMyasthenia GravisSchistosomicidesGoldEtorphinePeptide LibraryPyrrolidinesPainCyclazocineAmino Acid SequenceTime FactorsAzathioprinePeptides, CyclicAdrenal MedullaOpioid-Related DisordersDrug ToleranceVas DeferensSomatostatinAntimicrobial Cationic PeptidesGuinea PigsIleumBenzeneacetamidesRats, Sprague-DawleyBrainNitric OxideAnalgesiaPain MeasurementProteinuriaInjections, IntraventricularChromaffin System