弥漫性脑损伤脑组织中bcl-2 mRNA、bax—mRNA的表达与凋亡率的变化

The expression of bax-mRNA, and bcl-2 mRNA in brain and apoptosis following diffuse brain injury

目的探讨弥漫性脑损伤脑组织不同时间段bax—mRNA、bcl-2mRNA表达及与脑细胞凋亡的关系。方法依据Marmarou’s弥漫性脑损伤动物模型有改进，应用SD雄性大鼠55只，随机分为两组：假手术（对照组）（n=5）和弥漫性脑损伤组（n=50），损伤组再按照不同时问段分组（Tt=5），损伤后大鼠自由进食饮水，按0．5…136、12、24、48、72h、1周、2周等时间段提取大鼠皮层脑组织，一部分脑组织应用实时逆转录-聚合酶链反应（realtimeRT—PCR）检测对照组与不同时间段外伤组bax—mRNA、bcl-2mRNA表达，另取一部分皮层脑组织利用流式细胞仪进行脑细胞凋亡率测定。结果对照组及各时间段外伤组bcl-2mRNACt值分别为40．629±0．483、40．673±0．733、40．075±0．763、39．503±0．642、38．617±0．942、38．032±0．579、35．881±0．699、33．269±0．082、32．062±0．581、34．848±0．417、38．892±0．308，bcl-2mRNA荧光强度对照组与不同时间段外伤组之间的比较组间差异有统计学意义（P〈0．05）；对照组及各时间段外伤组bax-mRNA Ct值分别为：27．787±0．523、30．117±0．477、30．669±0．367、31．263±0．413、31．696±0．304、31．724±0．409、32．3134-0．391、33．59±0．325、34．271±0．366、31．191±0．342、30．475±0．659，bax—mRNA荧光强度对照组与不同时间段外伤组之间的比较组间差异有统计学意义（P〈0．01）；对照组及各时间段外伤组流式细胞仪测定凋亡率分别为：4．08±0．32、4．11±0．52、4．25±0．35、4．67±0．56、5．05±0．24、5．93±0．42、6．77±0．33、8．66±0．41、10．77±0．58、7．32±0．23、5．03±0．41。流式细胞仪测定凋亡率对照组与各时间段外伤组之间的比较组问差异有统计学意义（P〈0．05）。结论（1）外伤后bcl-2mRNA表达有降低的趋势，72h达到最低点。（2）外伤后bax-mRNA表达有增高趋势，72h达到高峰随后开始下降。（3）外伤后脑细胞凋亡有增高趋势，72h达到高峰，脑细胞凋亡的增加，可能县外伤后脑神经功能减退或丧失的一个原因。

Objective To investigate the expression of bax-mRNA,bcl-2 mRNA in brain and apoptosis of brain cells at different time points following diffuse brain injury （DBI）. Methods Fifty-five male SD rats were randomly divided into two groups：control （n = 5 ）, DBI （divided into 10 subgroups, n =5 in each）. Diffuse contusion and laceration of brain was produced by Marmarou＇ s brain injury model with a little modification. The expression of bax-mRNA and bcl-2 mRNA was detected by real time PCR. The apoptosis of brain cells was measured by flow cytometry. Results The expression of bcl-2 mRNA was downregulated following DBI, and there was significant difference in the expression of bcl-2 mRNA among groups,P 〈 0.01. The expression of bax-mRNA was upregulated following the DBI with the difference being significant among groups ,P 〈 0.01. The apoptosis rate in brain cells was increased following DBI with the difference being significant among groups,P 〈 0.001. Conclusion （ 1 ） The expression of bcl-2 mRNA in damaged brain was downregulated following DBI, and reached the peak at 72 h. （2） The expression of bax-mRNA was upregnlated following DBI, and reached the peak at 72 h. （3） The apoptosis rate of l brain cells was increased following DBI,which may be the cause resulting in the neurologic impairment following DBI.