内质网应激对p38MAPK调控在脑缺血再灌注损伤中的作用及鹰嘴豆芽素A的干预

Various pathophysiologic mechanisms are involved in the cerebral ischemia/reperfusion (I/R) injury. The contemporary focal issues are searching for the promising targets in the prevention and treatment of stroke. It has reported that endoplasmic reticulum stress (ERS) gets involved in the pathological damage process of I/R injury, and there exist close correlations between ERS, inflammation, and oxidative stress. It is suggested that ERS probably modulates p38 MAPK signaling pathway in cerebral I/R injury. We have found that biochanin A, a typical phytoestrogen, exhibited anti-inflammatory and anti-apoptosis effects by inhibiting p38 MAPK signaling pathway, subsequently improving the brain function in cerebral I/R rats. However, it deserves further research whether the neuroprotective effect of biochanin A is related to the modulation of ERS on p38 MAPK signaling pathway in I/R injury. Therefore, we proposed the following assumption: the neurons endoplasmic reticulum stress continuously exists in cerebral I/R, and it can reduce the capacity of neurons restoring from disorders, subsequently p38 MAPK signaling pathway is activated. As a result, the infernal circle finally leads to brain tissue inflammatory reaction and neurons apoptosis. The neuroprotective effect of biochanin A probably related to affecting ERS and inhibiting p38 MAPK signaling pathway. The project aims to, through overexpressing and silencing GRP78 or CHOP (the key molecules in the ERS), explore the relationship between ERS and p38 MAPK signaling pathway, research its effects in cerebral I/R injury and the therapeutical mechanism of biochanin A, which provide theoretical basis and new ideas on the application of biochanin A in the treatment of ischemic stroke.

脑缺血再灌注损伤的病理机制复杂，针对关键靶点对其进行有效防治是国内外研究的热点。有研究表明内质网应激（ERS）参与了缺血再灌注损伤，并与炎性反应、氧化应激关系紧密，提示ERS对p38 MAPK信号通路可能起调控作用。我们研究发现，植物雌激素鹰嘴豆芽素A可抑制p38，减轻炎性反应和抗凋亡，对大鼠脑缺血再灌注具有保护作用。这一作用是否与ERS对p38 MAPK信号通路的调控有关，值得深入探讨。故提出假设：脑缺血再灌注损伤时ERS持续存在，不能恢复神经细胞自稳，激活了p38 MAPK信号通路，导致脑组织炎性反应和细胞凋亡，鹰嘴豆芽素A可能影响ERS，抑制p38 MAPK激活。本课题拟通过在神经细胞和动物脑内过表达或沉默ERS中的关键分子GRP78和CHOP，研究ERS对p38 MAPK信号通路的调控，探讨其在脑缺血再灌注中的作用，及鹰嘴豆芽素A的治疗机制，为缺血性脑卒中的防治开拓新思路。

针对脑缺血再灌注损伤发病机制中的关键靶点进行有效防治及药物开发是脑卒中研究的热点问题。国内外研究表明，内质网应激（ERS）参与了缺血再灌注脑损伤，并与炎性反应、氧化应激等关系紧密，提示ERS对炎症相关的p38 MAPK信号通路可能起调控作用。我们研究发现，植物雌激素鹰嘴豆芽素A可抑制p38磷酸化活性，减轻炎性反应和抗凋亡，对大鼠脑缺血再灌注损伤具有保护作用。这一作用是否与ERS对p38 MAPK信号通路的调控有关，值得深入探讨。本项目通过体内外实验建模，证实在脑缺血再灌注过程中，内质网应激与p38 MAPK信号通路的活化存在着相互促进的关系，两者共同加剧了脑组织损伤。鹰嘴豆芽素A可改善大鼠脑缺血再灌注模型、衣霉素诱发的神经元应激大鼠模型和胎鼠皮质神经元内质网应激模型、皮质原代神经细胞氧糖剥夺模型的内质网应激状态，抑制p38 MAPK信号通路的活化，减轻炎症反应，发挥其神经保护作用。我们的研究结果为鹰嘴豆芽素A应用于缺血性脑卒中的靶向治疗提供了实验基础，而且也为开发其他植物雌激素的神经保护作用及机制研究提供了借鉴和新的思路。以期寻找同类药物共同作用的靶点，使中国的传统中草药更广泛地走向临床应用，在治疗缺血性脑血管疾病中成为可能。