the intraventricular injection of methionine-enkephalin ( 50 to 100 micrograms ) or [ d-ala2 ] -methionine-enkephalinamide ( 1.5 to 12 micrograms ) , a synthetic enkephalin analog resistant to enzyme degradation , caused a marked dose-dependent increase in dihydroxyphenylacetic acid and homovanillic acid concentrations in the rat striatum .
C0014295
methionine-enkephalin
C0014298
enkephalin