whereas d-ala2-d-leu5-enkephalin ( 1 , 3 or 10 micrograms ) and d-ser2-leu-enkephalin- ( thr6 ) ( 10 micrograms ) were also efficacious in inhibiting transit by the i.c.v . route , the more delta selective d-pen2-l-cys5-enkephalin ( 1 , 3 , 10 or 20 micrograms ) was not .
C0014294
leu-enkephalin
C0014298
enkephalin