21. Effects of opioid peptide agonists selective for μ, δ and κ receptors on identified dorsal horn neurons

The intrathecal infusion of opioid receptor agonists reduces behavioural responses to cutaneous noxious thermal stimuli. Compounds selective for μ- and δ-opioid receptors are clearly effective (Schmauss & Yaksh 1984) but a role for κ receptors is less well established (Han & Xie 1984). The dynorphins, which are present in the dorsal horn, are selective ligands for the K receptor (Corbett et al. 1982). The effects of a dynorphin and those of μ- and δ-selective enkephalin analogues DAGO and DADL, are compared here on the cutaneous sensory responses of single identified dorsal horn neurons whose axons ascend towards supraspinal regions (spinocervical tract, SCT neurons).