Spontaneous morphine withdrawal from the rat spinal cord

Summary A characteristic and reproducible sign of narcotic withdrawal is the naloxone induced increase in arterial pressure. In morphine-dependent rats allowed to undergo spontaneous withdrawal (6–24 h) and then transected at the spinal C-1 level, arterial pressure was maintained at a significantly higher level than either spinal-transected nondependent controls or morphine-dependent, spinal-transected rats pithed from C-1 to L-4. These findings indicate that the morphine-dependent spinal cord, independent of supraspinal influences, is able to exhibit an autonomic component of spontaneous withdrawal.This study was supported by the Medical Research Service of the Veterans Administration. A preliminary report of aspects of this work appeared in Soc. Neurosci. Abs.10 (1984) 1113.