Survival of motor neurons and expression of β-amyloid protein in the aged rat spinal cord

Abstract

The present study investigated expression of β-amyloid protein (AP) and Amyloid precursor protein (APP) in spinal motor neurons of young adult (3 month old) and aged (26-30 month old) rats. The total number of spinal motor neurons in the seventh cervical (C7) spinal segment was also examined in both young adult and aged rats. There was an ~21% (p < 0.001) decrease in the number of motor neurons of the C7 spinal segment in aged rats compared with young ones. Immunoreactivity (IR) of AP and APP was not observed in spinal motor neurons of young adult rats. In contrast, ~50% of the spinal motor neurons of the aged rats were APP positive. Furthermore, extensive immunoreactivity was found in the processes of spinal motor neurons of aged rats. These results have shown that AP and APP is coincident with the loss of motor neurons in the spinal cord of aged rats, and might be associated with the degenerative processes of ageing motor neurons. (C) 2000 Lippincott Williams and Wilkins.