Antinociceptive activity of salmon calcitonin injected intrathecally in the rat

Salmon calcitonin injected intrathecally in unanesthetized rats produced long-lasting, dose-dependent elevations of nociceptive threshold as measured in the hot plate test. This antinociceptive action was non-opiate in nature as it was uninfluenced by the narcotic antagonists naloxone and MR 1452; moreover, the peptide was still able to raise the nociceptive threshold in morphine-tolerant rats. It is suggested that the spinal cord may represent one of the sites of action for calcitonin-induced antinociception.