the opioid peptides used in this study were [ met5 ] -enkephalin ( me ) , [ leu5 ] -enkephalin ( le ) , fmrfamide , [ met5 ] -enkephalyl-arg6-phe7 ( meap ) , peptide e , and the non-selective opioid agonist , etorphine .
C0205753
opioid peptides
C0014298
enkephalin