the stimulatory action elicited by 10 ( -8 ) m methionine-enkephalin or dynorphin a ( 1-17 ) was completely antagonized by 10 ( -8 ) m naloxone or mr 1452 , respectively , whilst 10 ( -8 ) m naloxone exerted only a partially antagonistic action against the effect produced by 10 ( -8 ) m dynorphin a ( 1-17 ) , significantly more accentuated than the action of 10 ( -8 ) m mr 1452 versus the same dose of methionine-enkephalin .
C0014295
methionine-enkephalin
C0014298
enkephalin