Effects of mild hypothermia on expression of HSP70 protein and HSP70 mRNA and cell apoptosis at CA3 area of hippocampus in rats after diffuse brain injury

Objective: To observe the effects of mild hypothermia on the expression of HSP70 protein and HSP70 mRNA and the cell apoptosis at CA3 area of hippocampus in rats following experimental diffuse brain injury(DBI), and to explore the neuroprotective mechanism of mild hypothermia at molecular level. Methods: The rats were divided into control, sham-operated, only DBI and mild hypothermia treatment after DBI groups. The marmarou′s method was used to establish the animal model of DBI. Immunohistochemistry, RT-PCR and flow cytometer were separatively performed to examined the expression of HSP70 protein and HSP70 mRNA and the cell apoptotic ratio at CA3 area of hippocampus of rats in each group. Results: Compared to the control group, both the HSP70 expression at protein and mRNA level and cell apoptotic ratio at CA3 area of hippocampus in rat brain were increased following DBI (P0.05). When the mild hypothermia was used on the rats that were subjected to DBI, the HSP70 expression level was significantly increased (P0.01) in hippocampus CA3 area of rat brain, but the cell apoptosis ratio was decreased (P0.05). Conclusions: The neuroprotective efficacy of mild hypothermia on traumatic brain injury may correlated with improving HSP70 protein and HSP70 mRNA expression and decreasing the cell apoptosis in the injuryed brain.