( 2 ) rats made-tolerant to 100 hz ea analgesia showed a diminished response to intrathecal dynorphin a ( 1-13 ) , a kappa agonist , whereas the analgesic effect of the delta agonist [ d-pen2 , d-pen5 ] enkephalin ( dpdpe ) remained intact .
C0014298
enkephalin
C0525856
dpdpe