Segmental analysis of spinal cord monoamines after thoracic transection in the dog

The noradrenaline, dopamine and serotonin content from 10 segments of the dog spinal cord before and after a T7 transection were measured. The levels of amines were highest in the conus medullaris. However, when calculated per gram cord grey matter, noradrenaline was found to be concentrated in the midthoracic and sacral cord, while serotonin was concentrated in the mid-thoracic region. Levels of dopamine were very low throughout the spinal cord. Up to 3 days after a T7 transection, the levels of all 3 amines did not change in the distal cord segments. Ten days after transection the level of all 3 amines were less than twice tissue blank distally. This segmental analysis of dog spinal cord shows some potentially important differences from previous studies of cat and rat.