Enkephalin, Ala(2)-MePhe(4)-Gly(5)-Receptors, Neurokinin-3Neurokinin BReceptors, TachykininTachykininsReceptors, Opioid, muEnkephalinsNeurokinin AReceptors, Neurokinin-2Receptors, OpioidSubstance PEthylketocyclazocineEnkephalin, D-Penicillamine (2,5)-D-Ala(2),MePhe(4),Met(0)-ol-enkephalinEnkephalin, LeucineCyclazocineBenzeneacetamidesReceptors, Opioid, kappaReceptors, Opioid, deltaNeurokinin-1 Receptor AntagonistsEndorphinsReceptors, Neurokinin-1Narcotic AntagonistsMorphineIrisPiperidinesGuinea PigsNaloxoneAnalgesics, OpioidBenzamidesPeptide FragmentsDose-Response Relationship, Drug