抑制丝裂原活化蛋白激酶磷酸化对脑缺血后处理大鼠学习记忆及海马区神经细胞自噬的影响

Effect of inhibition of P38MAPK phosphorylation on learning and memory and autophagy in hippocampus of rats after cerebral ischemic postconditioning

目的探讨缺血后处理通过丝裂原活化蛋白激酶（P38MAPK）对缺血再灌注损伤大鼠海马神经元自噬及学习记忆障碍的影响。方法雄性大鼠96只随机分为假手术组（Sham组）、脑缺血再灌注模型组（CIR组）、脑缺血后处理组（CIP组）、脑缺血后处理联合SB203580组（CIP＋SB203580组），每组24只大鼠。采用Pulsinelli四血管闭塞法制作大鼠全脑缺血模型；水迷宫实验检测大鼠学习记忆能力；HE染色观察海马神经元形态学变化；免疫组化观察P38MAPK磷酸化水平、自噬相关蛋白Beclin-1、LC3-Ⅱ表达。结果与Sham组相比，CIR组大鼠穿越平台次数在各时间点均减少[24h：（3．04±0．20）次]，逃避潜伏期时间增长[24h：（58．38±1．52）s]，存活神经细胞数量明显减少[24h：（70．93±1．86）个]，免疫组化显示P38MAPK、LC3-Ⅱ、Beclin-1表达均明显增加（均P〈O．05）；与CIR组比较，CIP组大鼠在各时间点穿越平台次数增加[24h：（5．46±0．50）次]，逃避潜伏期时间缩短[24h：（52．42±1．53）s]，神经细胞存活数量在各时间点均增加[24h：（83．01±5．30）个]，免疫组化结果均显示P38MAPK表达量下降，LC3-Ⅱ、Beclin．1表达水平却增加（均P〈0．05）；与CIP组比较，CIP＋SB203580组在各时问点穿越平台次数增加[24h：（7．13±0．33）次]，逃避潜伏期时间缩短[24h：（48．04±1．39）s]，各时间点存活神经细胞数量增加[24h：（91．40±1．74）个]，免疫组化显示CIP＋SB203580组各时间点P38MAPK表达水平表达进一步下降，而LC3-Ⅱ、Beclin．1表达水平表达进一步增加（均P〈0．05）。结论缺血后处理可以改善缺血再灌注损伤大鼠学习记忆障碍，其机制可能与抑制P38MAPK调节自噬水平有关。

Objective To investigate the effect of ischemic postconditioning on autophagy and learning and memory impairment in rats with ischemia-reperfusion injury by P38MAPK. Methods Ninty-six rats were randomly divided into sham group （Sham group）, cerebral ischemia reperfusiou group （CIR group） ,cerebral ischemic postconditioning group （CIP group） and cerebral ischemic postconditioning combined with SB203580 group （CIP ＋ SB203580 group） ,and 24 rats in each group. The rat model of cerebral isehemia was established by Pulsinelli four-vessel occlusion. The learning and memory abilities of rats were measured by Morris water maze. HE staining were used to detect the morphological changes of hippocampal neurons. The phosphorylation of P38MAPK and Beclin-1 ,LC3-1/expression were observed by immunohisto- chemistry. Results Compared with the Sham group, the number of crossing the platform decreased （24 h：（3.04＋0.20） times） , and the escape latency was longer in CIR group（ 24 h： （58.38± 1.52） s） （all P〈0.05 ）. The number of survival neurons reduced （24 h ：70.93± 1.86） , and the expression of P38MAPK, LC3-Ⅱ, Bec- lin-1 in immunohistochemistry were increased in CIR group （all P〈0.05）. Compared with CIR group, the number of crossing the platform at each time point increased （24 h： （5.46±0.50） times）, the escape latency was shorter （ 24 h ： （ 52.42±1.53 ） s ） , the number of survival neurons increased at eaeh time point （ 24 h ： （83.07±5.30）） and the expression level of P38MAPK decreased in the CIP group,while the expression level of LC3-Ⅱ, Beclin-1 increased （ all P〈0.05） .Compared with the CIP group,the number of crossing the platform （ （ 24 h ： （ 7.13±0.33 ） times ） , the escape latency was shorter （ 24 h ： （ 48.04 ± 1.39 ） s ）, the number of survival neurons increased at each time point（ 24 h ： （ 91.40± 1.74） ） , and the expression of P38MAPK was down-regulated,while the expression of LC3-Ⅱ ,Beclin-1 were up-regulated in CIP ＋ SB203580 group（ all P〈 0.05）. Conclusion Ischemic postconditioning can improve learning and memory impairment in rats with ischemia-reperfusion injury by P38MAPK regulating autophagy.