Effects of traumatic injury on dynorphin immunoreactivity in spinal cord

Traumatic spinal cord injury in rats resulted in a significant eleation of dynorphin A immunoreactivity in spinal cord tissue at the level of, and below, the site of injury. [Leu5]enkephalin levels in the same tissue samples were not significantly altered following severe injury. Dynorphin A immunoreactivity was found in the fraction relatively enriched in synaptosomes after subcellular fractionation of spinal cord tissue. The dynorphin A content of this fraction was not significantly changed following injury, suggesting that dynorphin containing nerve terminals and axons are not severely damaged as a result of the injury.