Effect Of Propofol-mild Hypothermia On Apoptosis Of Nerve Cells In Rats After Brain Injury

Background and objective: Secondary brain injuries after traumatic brain injury (TBI) can cause the further damage of the structure and function in the brain tissue, which is one of the main factors to cause the death and dysfuction of patients. Apoptosis of nerve cells is the essential reason of the cell death. Preventing the apoptosis process of the injured brain cell can contribute to the recovery and improve the life quality of patients. In this experiment, the effect of propofol-mild hypothermia on the apoptosis of nerve cells was explored in rat's brain by investigating the level and expression of Bax and Bcl-2.Methods: By applying Feeney's brain injury model, health male SD rats were divided randomly into five groups: sham-injured group (S), only treated with opening the skull without brain injury; model group (M), treated as Feeney's brain injury model; mild hypothermia-treated group (H), 15 minutes after brain injury, maintained the body temperature between 32~34℃(anal temperature) for 3 hours by physical hypothermia method; propofol-treated group (P), propofol (50mg/kg) injected intraperitoneally immediately after brain injury, then the same dose was administered after 1 hour; propofol-mild hypothermia-treated group (PH), propofol injected combined with mild-hypothermia. Two time points, 24-hour and 48-hour, were set into each group, and eight rats were for each time point. The content of water in the injured brain was measured by the dry-wet method, the levels of Bax and Bcl-2 mRNA were detected by RT-PCR, the number of apoptotic neuron around the injured cerebral cortex was quantified by TUNEL method, the expression of Bcl-2 and Bax was observed by immunohistochemical staining.Results:(l) The content of water increased in the injured brain tissue after 24 hours and 48 hours. Propofol-mild hypothermia treatment could markedly reduce the water content. (2) Little TUNEL (+) neuron was observed in Group S. TUNEL (+) nerve cells increased round the injured brain tissue in Group M.Compared with Group M, the quantity of TUNEL (+) in Group H and P was reduced (p<0.01). Compared with Group M, H and P, the quantity of TUNEL (+) nerve cells in Group PH was decreased significantly (p<0.01).