Apoptosis And Expression Of CD95 After Acute Spinal Cord Injury

Objectives We examined the cellular distribution of apoptosis following T8-T9 spinal cord injury, and explored the relationship between apoptosis and the possible role of CD95 protein in initiating post-traumatic programmed cell death. Methods The spinal cord injury of the Wistar rats were induced with Allen sway by a 10gx2.5cm impact on the posterior T8-T9 spinal cord. Rats were sacrificed at 1h, 4h, 8h, 24h, 72h, 7d, 14d, 21d after injury (n=6 for each time point). Five segments of each spinal cord were cut for morphological studies, including hematoxylin and eosin staining, immunohistochemical staining and the terminal deoxynucleotidyl transferase-mediated deoxy-uridine triphosphate nick end labeling (TUNEL) methods. Results In injuried spinal cord, CD95 immunoreactivity was present in gray matter of the injured region at 4h after spinal cord, with a maximum presence at 8h. CD95 positive cells were mostly detected in gray matter. The TUNEL-positive cells were found in the compressed region at 4h after spinal cord injury, with a maximum presence at 24h in the compressed segment, and labeled glial cells in white matter reached a peak at 72h. The TUNEL-positive cells were neuron and glial cells in gray matter, especially the latter. Six additional segments of spinal cord from control rats did not show any CD95 protein or TUNEL immunoreactivity. Conclusions The apoptosis of the injuried spinal cord has its special distribution. The high expression of CD95 protien after spinal cord injury may play an important role in induction of normal cells to apoptosis.