Sonic Hedgehog 信号通路在高压氧预处理诱导 “脑缺血耐受” 中的作用及机制研究

The prevention of cerebral ischemic injury is an important scientific problem that should be solved urgently. Hyperbaric oxygen preconditioning induces tolerance to subsequent cerebral ischemia, and because of efficacy, lasting effect and simplicity, which may be a promising approach for protecting cerebral ischemic injury in clinic. However, the uderlying mechanism is far from elucidated. Sonic hedgehog (Shh) is a key regulatory factor in the development and differentiation of nervous system. Recent studies confirm that Shh signaling pathway plays an important role in vascular regeneration, neurogenesis and nerve repair after cerebral ischemia-reperfusion injury. Our previous studies have demonstrated that hyperbaric oxygen preconditioning increases the expression of Shh protein. Inhibiting the protein expression of Shh reverses the ischemic tolerance induced by HBO preconditioning, strongly suggesting that Shh signaling pathway may be play an important role in the neuroprotective effect of hyperbaric oxygen preconditioning. Based on the previous studies, The present study aimed to investigate the regulatory role and possible molecular mechanism of Shh signaling pathway in cerebral ischemic tolerance induced by hyperbaric oxygen preconditioning with the methods of functional analysis, morphology and molecular biology and so on in vivo and in vitro, using gene knockdown, siRNA interference and lentivirus infection to regulate Shh signaling pathway. The present study may provide a new evidence of hyperbaric oxygen preconditioning-induced tolerance to cerebral ischemia and inherent protection mechanisms of the brain. Moreover, it may offer more effective targets for preventing cerebral ischemic injury. These results have important theoretical and clinical significance.

脑缺血损伤的防治是亟待解决的重要科学问题。高压氧预处理可诱导“脑缺血耐受”，因效果显著、作用持久、简便易行，有望成为临床预防脑缺血损伤的有效手段，但机制远未阐明。Sonic hedgehog（Shh）是神经系统发育和分化的关键调控因子，新近研究证实，Shh信号通路与脑缺血再灌注损伤后血管再生、神经发生与修复密切相关。我们前期研究发现，高压氧预处理可上调Shh的表达，Shh拮抗剂可逆转高压氧预处理诱导的脑缺血耐受效应，强烈提示Shh信号通路可能参与高压氧预处理脑保护机制并起重要作用。本项目拟在前期研究的基础上，利用基因敲除、慢病毒感染、siRNA干扰等技术调控Shh信号通路，采用功能、形态和分子生物学等综合方法，从整体水平、细胞水平研究Shh信号通路在高压氧预处理诱导脑缺血耐受中的关键作用及分子机制，为进一步揭示高压氧预处理机制提供新的理论依据，从更深层次挖掘脑的内源性保护机制，为开发更有效

脑缺血疾病的发病是导致人群死亡的主要原因之一。脑缺血的治疗仍然是研究人员的临床挑战，脑缺血损伤的防治是亟待解决的重要科学问题。本课题研究了紫檀芪和芒柄花苷对缺血再灌注大鼠脑损伤的治疗作用，并探讨了其作用机制。我们将大鼠分为正常组，假手术组，MCAO组和MCAO+紫檀芪（25 mg/kg）组或MCAO+芒柄花苷（10mg/kg体重/20mg/kg体重）组。对各组大鼠进行了神经学评分，分析脑含水量，梗塞体积等。评估氧化应激标志物SOD，CAT，GSH，MDA等水平。评估炎性细胞因子和炎症介质的含量。我们发现紫檀芪和芒柄花苷能够显著减少脑梗塞体积，改善神经功能评分，具有神经保护功效。紫檀芪和芒柄花苷增强脑损伤大鼠的抗氧化能力。紫檀芪和芒柄花苷降低了促炎性因子的表达水平，同时上调了抗炎性因子的表达。紫檀芪治疗显著改善体重，抑制血糖水平和大脑重量。紫檀芪也能显著改善肝功能和肾功能。紫檀芪抑制脑内细胞肿胀，细胞崩解，巨噬细胞浸润，单核细胞浸润和多形核白细胞脱粒。综上，紫檀芪和芒柄花苷可通过抗氧化和抗炎症机制对大鼠脑缺血损伤具有神经保护作用。使神经元损伤最小化。该研究的所有发现都表明，紫檀芪和芒柄花苷可以作为治疗脑缺血损伤的有效药物。