injections of different enkephalin analogs were also made into the sn , [ d-ser2 ] -leu-enkephalin ( 10 micrograms , 14.5 nmol ) and [ d-ala2 , d-ala3 ] -met-enkephalin ( 10 micrograms , 15 nmol ) also produced contralateral circling after unilateral intranigral injection .
C0014298
enkephalin
C0014295
met-enkephalin