中文摘要：

目的探讨二十二碳六烯酸（docosahexaenoic acid,DHA）对大鼠缺血性脑卒中神经损伤的保护作用及其机制。方法利用60只280~330 g成年SD雄性大鼠建立永久性局灶脑梗死模型（permanent middle cerebral artery occlusion,pMCAO）,按随机数字表法分为3组（n=20）：假手术组、模型载体空白组（pMCAO＋Veh）和模型DHA给药组（pMCAO＋DHA）。建模成功后,按预设时间点对动物体质量、生存时间、神经功能、脑梗体积等大体指标进行评测;利用HE、Nissl染色对脑组织形态学改变进行观察;Western blot检测神经细胞自噬相关蛋白变化规律。结果造模后24、72 h,pMCAO＋Veh组动物体质量及生存率较假手术组出现明显下降（P〈0.05）,DHA给药可明显改善上述指标,但差异无统计学意义（P〉0.05）;pMCAO＋Veh组第7天生存率仅为38%,DHA早期干预可使第7天生存率提高至52%,但2组差异无统计学意义（P〉0.05）,DHA可明显改善由疾病模型造成的神经功能,包括认知、感觉、运动功能,从而获得更高的神经功能分数及更少的平衡木错失（P〈0.05）。建模72 h后TTC染色发现,pMCAO＋DHA组较pMCAO＋Veh组可减少约17%的梗死体积（P〈0.05）;HE及Nissl染色发现,DHA给药可显著减轻皮层梗死区神经细胞的病理性损伤;Western blot蛋白检测,DHA可显著抑制梗死后mTOR表达（P〈0.01）,同时增强LC3Ⅰ/Ⅱ表达（P〈0.05）。结论 DHA可显著减轻由缺血性脑卒中引起的病理性改变,其保护机制可能为负性调控mTOR通路作用从而激活自噬。

英文摘要：

Objective To evaluate the neuroprotective effect of docosahexaenoic acid（ DHA） in rats with permanent focal cerebral ischemia and explore the possible mechanisms. Methods Sixty male SD rats were randomly divided into 3 groups（ n = 20）,namely the sham-operated group,permanent middle cerebral artery occlusion（ pMCAO） with vehicle treatment group（ pMCAO ＋ Veh）,and pMCAO with DHA treatment group（ pMCAO ＋ DHA）. In the latter two groups,the rats received intraperitoneal injections of saline and DHA 3 h after pMCAO,respectively. The body weight,survival rate,neurological function score and cerebral ischemia volume of the rats were measured at different time points after the operation. HE and Nissl staining were used to examine the pathological changes in the brain tissues,and the expressions of autophagy-related proteins were detected with Western blotting. Results At 24 and 72 h after the operation,the rats in pMCAO ＋ Veh group showed significantly reduced body weight and lower survival rate as compared with the sham-operated rats（ P〈0. 05）; treatment with DHA improved the body weight and promoted survival of the rats following pMCAO,but these effects were not statically significant（ P〉0. 05）. In pMCAO ＋ Veh group,the survival rate of the rats was 38% on day 7,as compared with 52% in DHA treatment group（ P〈0. 05）.DHA obviously improved the cognitive,sensory and motor function deficits of the rats at 24 and 72 h after pMCAO,significantly increased the neurological scores of the rats and improved their performance in balance beamtest（ P〈0. 05）. At 72 h after the operation,the results of TTC staining showed that DHA treatment significantly reduced the cerebral infarction volume by 17% as compared with saline treatment（ P〈0. 05）.HE and Nissl staining showed alleviated pathologies in the neural cells in the ischemic cerebral cortex in DHAtreated rats. As shown by Western blotting,DHA treatment obviously suppressed the expression of mTOR protein following pMCAO（ P?