中文摘要：

目的探讨茶氨酸预先给药对大鼠脑缺血再灌注损伤时神经元DNA修复功能的影响。方法雄性SD大鼠108只，体重290～310g，15周龄，采用随机数字表法，将其分为3组（n=36）：假手术组（s组）、缺血再灌注组（I／R组）和茶氨酸预先给药组（T组）。采用四血管阻断法制备大鼠全脑缺血再灌注损伤模型。T组在夹闭双侧颈总动脉前4h时静脉注射茶氨酸1g／kg，其它2组给予等容量生理盐水，每组分别于再灌注2、6、12、24、48、72h时取6只大鼠，取海马，光镜下进行海马CA1区存活神经元计数，采用TUNEL法检测海马CA1区神经元凋亡情况，计算凋亡指数，采用免疫组化法测定DNA修复蛋白X线修复交叉互补蛋白1（XRCC1）和Ku70的表达。结果与s组比较，I／R组再灌注6、12、24、48、72时海马存活神经元计数减少，凋亡指数升高，再灌注2、6、12、24、48、72h时海马XRCC1和Ku70的表达下调（P〈0．01）；与I／R组比较，T组再灌注12、24、48、72h时海马存活神经元计数增加，再灌注6、12、24、48、72h时海马凋亡指数降低，再灌注2、6、12、24、48、72h时海马XRCC1和Ku70的表达上调（P〈0．01）。结论茶氨酸预先给药减轻大鼠脑缺血再灌注损伤的机制与增强神经元DNA修复功能，减少神经元凋亡有关。

英文摘要：

Objective To investigate the effect of theanine pretreatment on DNA repair function in neurons during brain ischemia-reperfusion （I/R） injury in rats. Methods One hundred and eight male Sprague-Dawley rats, weighing 290-310 g, aged 15 weeks, were randomly divided into 3 groups （n = 36 each） using a random number table： sham operation group （ S group） , I/R group and theanine pretreatment group （T group）. Global cerebral I/R was produced by 4-vessel occlusion method. Bilateral vertebral arteries were electrically cauterized, and bilateral common carotid arteries were clamped for 6 min. Thean- ine 1 g/kg was injected intravenously at 4 h before clamping bilateral comnlon carotid arteries in T group, and the equal volume of normal saline was given in the other two groups. At 2, 6, 12, 24, 48 and 72 h of reperfusion, 6 rats were selected in each group and sacrificed, the brains were removed, and the hippo- campus was isolated for determination of the number of viable neurons in the hippoeampal CAI region （ with a light microscope） , apoptosis in neurons in the hippocampal CA1 region （by TUNEL） , and expression of DNA repair protein X-ray repair cross-complenlenting group 1 （ XRCC 1 ） and Ku70 （ by immunohistochem- istry）. The apoptotic index was calculated. Results Compared with S group, the number of viable neu- rons was significantly decreased, and the apoptotic index was significantly increased at 6, 12, 24, 48 and 72 h of reperfusion, and the expression of XRCC1 and Ku70 was significantly down-regulated at 2, 6, 12, 24, 48 and 72 h of repeffusion in I/R group （P〈0.01）. Compared with I/R group, the number of viable neurons was significantly increased at 12, 24, 48 and 72 h of reperfusion, the apoptotic index was significantly decreased at 6, 12, 24, 48 and 72 h of reperfusion, and the expression of XRCC1 and Ku70 was significantly up-regulated at 2, 6, 12, 24, 48 and 72 h of reperfusion in T group （P 〈 0. 01 ）. Conclusion The mechanism by which theanine pretreatment at