morphine and the opioid peptides , ( d-ala2 , d-leu5 ) -enkephalin ( dadl ) , morphiceptin , beta-endorphin , and tyr-d-ser-gly-phe-leu-thr ( dsthr ) caused a concentration-dependent , naloxone-reversible shift to the left in the input-output ( io ) curve constructed by plotting the population spike as a function of the field epsp .
C0205753
opioid peptides
C0014298
enkephalin