the opioid peptides met- and leu-enkephalin , dynorphin ( 1-13 ) , and beta-endorphin and the narcotic analgesics , morphine , levorphanol , and dextrorphan all produced a dose-dependent inhibition of nicotine ( 5 x 10 ( -6 ) m ) -mediated release of [ 3h ] norepinephrine ( [ 3h ] ne ) from bovine adrenal chromaffin cells in culture .
C0205753
opioid peptides
C0013355
dynorphin