Catecholamine alterations attending spinal cord injury: a reanalysis

The catecholamine response of injured tissue after severe spinal cord injury (SPI) remains a puzzling controversy. This study was undertaken in an attempt to resolve that controversy. The influence of the biochemical assay method, the magnitude of injury, and the spinal cord region injured on catecholamine levels was determined in the cat spinal cord. It was found that the concentration of norepinephrine (NE) in the traumatized spinal cord is dependent on both the magnitude and the region of injury. The relatively large tissue samples necessitated by the older, less sensitive assay methodology show little or no change in NE levels after a 500-g/cm injury in the cat. When regional samples are analyzed with more sensitive methods, a net depression in the NE level of local tissue is observed. The results of earlier studies from this laboratory indicating an increase in tissue NE after trauma were apparently artifactual, presumably due to the nonselective nature of the biochemical assay used at that time. Dopamine levels were not elevated after SCI, and previous reports from other laboratories indicating an increase in dopamine levels were probably also errant due to methodology-related problems.