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

The present study investigated expression of beta-amyloid protein (AP) and Amyloid precursor protein (APP) in spinal motor neurons of young adult (3 m onth 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 b oth young adult and aged rats. There was an similar to 21% (p<0.001) decrea se in the number of motor neurons of the C7 spinal segment in aged rats com pared with young ones. Immunoreactivity (IR) of AP and APP was not observed in spinal motor neurons of young adult rats. In contrast, similar to 50% o f the spinal motor neurons of the aged rats were APP positive. Furthermore, extensive immunoreactivity was found in the processes of spinal motor neur ons of aged rats. These results have shown that AP and APP is coincident wi th the loss of motor neurons in the spinal cord of aged rats, and might be associated with the degenerative processes of ageing motor neurons. NeuroRe port 11:697-700 (C) 2000 Lippincott Williams & Wilkins.