the intradermal injection of mu ( morphine , tyr-d-ala-gly-nme-phe-gly-ol and morphiceptin ) , kappa ( trans-3,4-dichloro-n-methyl-n [ 2- ( 1-pyrrolidinyl ) cyclohexyl ] benzeneactemide ) and delta ( [ d-pen2.5 ] -enkephalin and [ d-ser2 ] - [ leu ] enkephalin-thr ) selective opioid-agonists , by themselves , did not significantly affect the mechanical nociceptive threshold in the hindpaw of the rat .
C0014298
enkephalin
C0014294
leu ] enkephalin