Inhibitory action of nociceptin on spinal dorsal horn neurones of the rat, in vivo

Intrathecally administered nociceptin (5, 50, 225 mu g) dose-relatedly inhibited the C-fibre evoked wind-up and post-discharge of dorsal horn neurones, but not the baseline C-fibre evoked responses. Spinal naloxone 50 mu g, but not 10 mu g, reversed the effects of nociceptin. Thus the antinociceptive role of nociceptin in the spinal cord differs from that of classical opioids.