intravenous bolus administration of the endogenous opioid , met-enkephalin ( 2.5 mg ) , and its potent and long-acting analogue , [ d-ala2 , n-phe4 , met ( o ) ol5 ] -enkephalin [ fk33-824 ( 250 micrograms ) ] , did not alter acth or cortisol secretion .
C0014295
met-enkephalin
C0014298
enkephalin