Changes in apoptosis-related protein (p53, Bax, Bcl-2 and Fos) expression with DNA fragmentation in the central nervous system in rats after closed head injury.

This study aimed to examine the temporal profile of neuronal apoptosis in the central nervous system (CNS) following closed head injury in rat. Fos immunoreactivity was detected in neuronal nuclei in the cerebral cortex at 2 h after head injury. At 4 h, Bax protein expression was elevated with a concomitant down-regulation of Bcl-2 expression. Along with this, a marked immunoexpression of p53 was also observed in these cells. Double immunolabelling study has shown the colocalization of Bax immunoreactivity with Bcl-2 and p53. In rats killed 1 day after injury, a variable number of transferase d-UTP nick-end labelling positive cells were observed. Present findings suggest that the upregulation of p53 and a shift in the ratio of Bcl-2 to Bax may contribute to neuronal apoptosis in the CNS after closed head injury.