Study of correlation between Caspase-3 expression and neural cell apoptosis after spinal cord injury in rats

Objective To investigate neural cell apoptosis and the changes of Caspase 3 expression after spinal cord injury in rats. Methods The spinal cord of rats were compressed at the level of T 8 、T 9 in moderate degree. The expression of Caspase 3 was detected by immunohistochemical study and RT PCR at 4,8,24,48,72 hours and 7,14,21 days after injury,The level of neuronal cell was deleted by the terminal deoxynucleotidyl transferase mediated DUTP nick end labeling (TUNEL) methods. Results There were few Caspase 3 expression (2.1±0.5) in normal spinal cord as detected by immunohistochemical study. The number of positive cells expressing Caspase 3 decreased at 8 hours after injury and peaked at 3d (189±12.7,P0.01). The protein expression of Caspase 3 by immunohistochemical staining was similar to the TUNEL time course date. A positive correlation was seen between Caspase 3 expression and neural apoptosis(r= 0.941 ). Caspase 3 mRNA increased at 4h and peaked at 48h(0.634±0.028)after trauma,and it decreased at 7d. The correlation between Caspase 3 mRNA and the level of neural apoptosis was positive(r=0.622). Conclusion There are neuronal apoptosis after spinal cord injury,Caspase 3 and protein expressions are enhanced in combination with neuronal apoptosis.