the opioid receptors involved in the supraspinal and spinal actions of [ d-pen2 , d-pen5 ] enkephalin ( dpdpe ) for production and/or modulation of analgesia were investigated in two thermal analgesic tests , the mouse warm water ( 55 degrees c ) tail-withdrawal assay and the radiant heat tail-flick test .
C0014298
enkephalin
C0525856
dpdpe