the ontogenesis of mu- and delta-opioid binding sites was studied using rat whole brain membranes and [ 3h ] - [ d-ala2mephe4-gly-ol ] enkephalin and [ 3h ] - [ d-pen2 , d-pen5 ] enkephalin as binding ligands .
C0014298
enkephalin
C0525856
d-pen2 , d-pen5 ] enkephalin