in opiate-naive rats , the endogenous opioid peptides , beta-endorphin , dynorphin ( 1-13 ) and met-enk-arg-phe ( meap ) and the synthetic enkephalin analogue d-ala2-d-leu5-enk ( dadle ) potently stimulated plasma corticosterone in a dose-dependent , naloxone reversible manner .
C0205753
endogenous opioid peptides
C0013355
dynorphin