the tail-flick assay in chronic implanted rats was used to test the analgesic potency of agonists selective for mu opioid receptors : [ d-ala2 , mephe4 , gly-ol5 ] enkephalin ( dago ) , tyr-d-ala-gly-nh ( ch2 ) 2-ch ( ch3 ) 2 ( trimu 5 ) and for delta receptor subtypes : [ d-ser2 , leu5 ] enkephalyl-thr6 ( dslet ) , [ d-thr2 , leu5 ] enkephalyl-thr6 ( dtlet ) and cyclic [ d-pen2 , l-pen5 ] enkephalin ( dplpe ) .
C0525773
dago
C0014298
enkephalin