PI3K/Akt通路在创伤性脑损伤中的表达及抗凋亡作用

Expression and anti-apoptosis effect of PI3K/Akt signal pathway on traumatic brain injury

目的研究创伤性脑损伤(TBI)后脑组织中Akt蛋白磷酸化激活情况及其在神经细胞凋亡中的作用。方法 24只雄性Wistar大鼠,采用自由落体颅脑损伤模型随机分成假手术组、外伤后1h、3h、6h、12h、1d、3d、7d组。于相应时间点处死后行蛋白免疫印迹法(western blot)检测磷酸化Akt(p-Akt)表达。另外36只雄性Wistar大鼠,随机分为假手术组、外伤组、外伤+抑制剂组、外伤+二甲基亚砜(DMSO)组,伤后1d统一处死。蛋白免疫印迹法及免疫组化检测p-Akt表达,TUNEL法检测神经细胞凋亡。结果脑外伤后3h p-Akt表达增加,于24 h达到高峰,给予P13K特异性抑制剂LY294002后Akt磷酸化减少,神经细胞凋亡明显增加。结论 P13K/Akt通路在脑外伤后激活并发挥抗凋亡的作用。

Objective： To study the phosphorylation of Akt after traumatic brain injury（TBI） and the relationship between the phospho-Akt （p-Akt） and neuronal apoptosis. Methods 24 male Wistar rats were randomly divided into sham-operated group and 1 h, 3 h, 6 h, 12 h, 1 d,3 d,7 d group after injury, which was made by weight-dropping method. All rats were killed at corresponding time points. Total of p-Akt in cerebral cortex were measured by western blot. Other 36 male Wistar rats were randomly allocated into sham-operated group, TBI group, TBI ＋ inhibitor group and TBI ＋ DMSO group. All rats were executed at one day after operation, p-Akt levels were measured by western blot and immunohistochemistry, apoptosis was detected by means of TdT-Mediated dUTP nick end labeling （TUNEL）. Results p-Akt was increased at 3h after TBI and achieved the peak at 24 hours. LY294002 （ the specific inhibitor of PI3 K family） could enhance the neuronal apoptosis rate by inhibiting phosphorylation of Akt. Conclusion Activation of PI3 K/Akt signal pathway are involved in cell survival after TBI.