[ 3h ] - [ d-ala2 , n-me-phe4 , gly ( ol ) 5 ] -enkephalin ( dago ) was used to selectively label mu receptors , [ 3h ] - [ d-pen2 , 5 ] -enkephalin ( dpdpe ) for delta receptors , and [ 3h ] -bremazocine for kappa receptors .
C0525773
dago
C0014298
enkephalin