a variety of central manipulations was made to distinguish the effects produced by [ d-ala2-me-phe4-gly ( ol ) 5 ] -enkephalin ( dago ) , a selective mu-opioid receptor ligand , from those of the delta ligand [ 2-d-penicillamine , 5-l-penicillamine ] -enkephalin ( dplpe ) , administered by either intracerebroventricular ( i.c.v . ) or by spinal intrathecal ( i.t . ) injection .
C0525773
dago
C0014298
enkephalin