Effects of mild hypothermia on the cell apoptosis and the express ion of apoptosis-regulatory proteins at CA3 area of hippocampus in rats after traumatic brain injury

Objective To observe the effects of mild hypotherm ia on the cell apoptosis and the expression of apoptosis-regulatory proteins( inc luding Bcl-2, Bax and Caspase-3) at hippocampal CA3 area of rats after traum atic brain injury(TBI) and to investigate the molecular mechanism of neuroprot ection of mild hypothermia treatment.Methods The rats were divided into three groups, including sham-operated, only TBI and mild hypothe rmia treatment after TBI group. A modified Marmarou's method was used to estab lish the animal model of TBI. Flow cytometer(FCM) and immunohistochemistry w ere seperatively performed to examine the cell apoptotic ratio and the expressio n of Bcl-2, Bax and Caspase-3 at hippocampal CA3 area of rat in each group. Results Compared to the sham-operated group, the cell apopt osis rate and Caspase-3 expression increased(P0.05) and Bcl-2/Bax express ion ratio decreased(P0.05) at hippocampal CA3 area of rat following TBI. Wh en the mild hypothermia was used on the rats that were subjected to the TBI, the cell apoptosis rate and Caspase-3 expression began to decrease(P0.05) and the Bcl-2/Bax expression ratio increased(P0.05) compared to the only TBI group.Conclusion The protective efficacy of mild hypothermi a on the TBI may correlate with regulating the expression of apoptosis-regu latory gene and decreasing the degree of nerve cell apoptosis.