Retrograde transport of horseradish peroxidase is specifically impaired in bulbospinal serotonin axons during experimental allergic encephalomyelitis

Bulbospinal monoamine-containing axons appear to be severely damaged in rats with the inflammatory and demyelinating disease, experimental allergic encephalomyelitis (EAE). This paper reports that although bulbospinal serotonin axons are damaged in the disease, cell bodies of origin in the medulla oblongata retain normal morphology. However, these serotonin cells are not able to retrogradely transport the enzyme horseradish peroxidase (HRP) from terminals in the lumbar spinal cord. Most non-serotonin-containing cells in the medulla which project to the lumbar spinal cord retain the ability to retrogradely transport HRP from the lumbar cord during the disease. These findings suggest that there is some specificity to spinal cord axonal damage during EAE.