the administration of the synthetic and stable opioid peptide [ d-ala2 , mephe4 , met ( o ) 5o1 ] enkephalin ( fk 33-824 ) at the dose of 0.2 mg/kg i.v . induced a rise in plasma levels of prolactin in the rat , an effect which was prevented by 1 mg/kg i.v . of the opiate antagonist naloxone .
C0205753
opioid
C0014298
enkephalin