糖原合成酶激酶3对大鼠创伤性脑损伤后认知功能的影响

Effect of glycogen synthetase kinase 3 on rats' cognitive function after traumatic brain injury

目的探讨糖原合成酶激酶3(GSK3)在创伤性脑损伤(TBI)诱导认知障碍中的作用。方法采用液压冲击仪(1.8 atm)建立Sprague Dewley大鼠TBI模型,检测TBI后1、3和7 d GSK3在Ser9位点的磷酸化水平,以观察GSK3的活性变化;损伤对侧行侧脑室立体定位注射GSK3抑制剂氯化锂;采用Western blotting检测氯化锂抑制GSK3的有效性;采用Morris水迷宫检测潜伏期和目标象限停留时间,以观察大鼠学习记忆能力的变化;采用Western blotting检测Tau蛋白在Ser404和Thr231位点的磷酸化水平。结果 TBI后第3、7天,GSK3在Ser9位点的磷酸化水平显著降低(P<0.01);侧脑室注射氯化锂可显著逆转TBI后GSK3在Ser9位点磷酸化水平的降低(P<0.05);TBI后大鼠的潜伏期和目标象限停留时间分别出现显著性增加和减少(P<0.01),而给予氯化锂后可显著逆转TBI诱导的潜伏期的增加(P<0.01)和目标象限停留时间的减少(P<0.05);TBI后Tau蛋白在Ser404和Thr231位点的磷酸化水平显著增加(P<0.01),而氯化锂注射可显著逆转TBI诱导的Tau蛋白过度磷酸化(P<0.01)。结论 TBI可通过激活GSK3来降低大鼠的学习记忆能力及Tau蛋白的过度磷酸化,提示GSK3在TBI所致认知功能障碍的发病机制中起重要作用。

Objective To investigate the role of glycogen synthetase kinase 3（GSK3） in pathological mechanism of cognitive deficit after traumatic brain injury（TBI）.Methods TBI model was built with fluid percussion device in Sprague Dewley rats.The phosphorylated GSK3 at Ser9 was examined to evaluate the activity of GSK3 at 1 day,3 and 7 days after TBI. GSK3 inhibitor LiCl was stereotactically injected into contralateral ventricle.The inhibitory effect of LiCl on the activity of GSK3 was examined by Western blotting.The latency to the platform and the time in targeted quadrant were recorded to evaluate the learning and memory with Morris water maze.The phosphorylated Tau at Ser404 and Thr231 was detected.Results The phosphorylated GSK3 at Ser9 was significantly declined at 3 and 7 days after TBI（P0.01）.Treatment of LiCl could effectively inhibited TBI induced decline of phosphorylated GSK3 at Ser9（P0.05）.The latency was increased（P0.01） and the time in the targeted quadrant was decreased（P0.01） after TBI,where as injection of LiCl could significantly reversed the change of latency（P0.01） and the time in the targeted quadrant（P0.05） induced by TBI.The phosphorylated Tau at Ser404（P0.01） and Thr231（P0.01） was increased after TBI,and using of LiCl could significantly deteriorated the TBI induced Tau hyperphosphorylation（P0.01）.Conclusion TBI can lead to the decline of learning and memory and tau hyperphosphorylation by activation of GSK3,it suggests that GSK3 plays an important role in the pathophysiology of TBI induced cognitive deficit.