three agonists with the highest degree of selectivity available for mu ( [ d-ala2 , nmephe4 , gly-ol ] enkephalin , dago ) , delta ( [ d-pen2 , d-pen5 ] enkephalin , dpdpe ) and kappa ( u-50,488h , u50 ) opioid receptors were compared for their activity in inhibiting acetic acid-induced writhing in mice .
C0014298
enkephalin
C0525773
dago