Dermorphin interaction with peripheral opioid receptors

The interaction of dermorphin with different peripheral opioid receptor subtypes was investigated in vitro, using the guinea pig ileum as representative tissue for μ, the mouse vas deferens for δ, the rabbit vas deferens for κ and the rat vas deferens for ε. The effect of dermorphin on each tissue preparation was compared with that of selective μ,δ, κ, ε agonists respectively morphine, met-enkephalinamide, ethylketocyclazocine and camel β-endorphin. Antagonism with naloxone was also tested and calculated as Ke. It is concluded that dermorphin mainly interacts with the μ receptors, although it also binds to ε receptors; the interaction with δ receptors is questionable, and the κ receptors are unaffected.