the distribution of mu , delta and kappa opioid receptors in the lower brainstem of the cat has been determined autoradiographically by studying the binding of tritiated [ d-ala2 , mephe4 , glyol5 ] [ tyrosyl-3,5-3h ] enkephalin ( dago ) , [ d-pen2 , d-pen5 ] [ tyrosyl-3,5- ( n ) -3h ] enkephalin ( dpdpe ) and [ 9-3h ] ethylketazocine ( ekc ) , respectively .
C0014298
enkephalin
C0525856
dpdpe