in order to determine the importance of opioid peptides in the central control of wakefulness , the synthetic analogue of met-enkephalin , fk 33-824 ( d-ala-2-phe-met- ( o ) -ol-enkephalin ) which is more resistant to enzymatic degradation , was perfused in increasing concentrations ( 20 , 100 , 200 , and 400 micgrograms/ml ) through the fourth cerebral ventricle of the conscious dog .
C0014295
met-enkephalin
C0014298
enkephalin