Abstract: Objective To investigate the expression of caspase-3in different posttraumati c intervals and severity of brain injury.Methods The study examined brain tissue samples of slight(n=24),severe(n=24)brain injury and control(n=6)of rat,using i mmunohistochemical staining,western-blot and RT-PCR method.Results Up-regulating of caspase-3expression was found in tissue from traumatic brain injury compared with controls in early1hour after TBI,and lasted for14days.The gray degree and threshold area of caspase-3positive cells is different in different severity of brain injury.Conclusion The increasing of caspase-3expression indicates that TBI exists.The gray degree,threshold area of caspase-3positive cells and the cleava ge degree of pro-caspase-3have association with the severity of brain injury.

Key words: cerebral contusion, casapse-3, post contusion intervals, severity, apoptosis