in decided contrast , opioid peptides such as methionine enkephalin , dynorphin- ( 1-13 ) , beta-casomorphan derivatives or short chain beta h-ep segments such as beta-ep 1-16 , beta-ep 1-19 , beta-ep 6-31 , beta-ep ( 1-5 ) - ( 16-31 ) , methionine enkephalin plus beta-ep 6-31 or the n-acetyl beta-bovine-ep did not antagonize the inhibitory action of beta h-ep .
C0205753
opioid peptides
C0013355
dynorphin