the continuous intrathecal infusion of morphine ( 2 , 6 , 20 nmol/h ) , sufentanil ( 0.06 , 0.2 , 0.6 nmol/h ) , [ d-ala2 , mephe4 , gly-ol5 ] enkephalin ( damgo ) ( 0.1 , 0.3 , 1.0 nmol/h ) or [ d-ala2 , d-leu5 ] enkephalin ( dadle ) ( 2 , 6 , 20 nmol/h ) in unanesthetized rats produces a dose-dependent increase in hot plate latency 1 day after pump implant followed by a gradual return to baseline values by days 3-4 , i.e . tolerance .
C0525773
damgo
C0014298
enkephalin