intracerebroventricular ( i.c.v . ) administration of the selective delta-receptor agonist , [ d-pen2 , d-pen5 ] -enkephalin ( dpdpe , 10.0-25.0 micrograms ) produced a significant preference for the drug-associated place and a similar effect was observed following i.c.v . injections of morphine ( 10.0 micrograms ) .
C0014298
enkephalin
C0525856
dpdpe