Neuroprotective mechanisms of EGb-761

描述（由申请人提供）：银杏叶提取物（EGb 761 ; EGb）是一种标准化提取物，是最著名的天然化合物之一，专门用于治疗神经系统疾病。来自提取物的成分可能具有协同效应，已被证明对氧化应激损伤具有保护作用。然而，银杏叶提供的细胞保护机制仍不清楚。我们测试的假设，银杏叶提取物的神经保护作用可能部分是由于血红素加氧酶1（HO 1）的诱导。我们和其他人已经报道了HO活性的调节可能在中风和阿尔茨海默病中具有直接的生理意义。通过使用培养的神经元，我们证明，EGb诱导HO 1的剂量依赖性的方式。有趣的是，我们的初步结果表明，用EGb预处理原代神经元，然后冲洗细胞，然后通过H2 O2或谷氨酸诱导毒性，EGb显示了神经保护作用。血红素加氧酶抑制剂（SnPPIX）可消除这种作用。我们认为银杏叶提取物在缺血性疾病中的保护作用可能是通过血红素降解及其代谢产物的有益作用来介导的。我们将首先确定EGb处理的WT小鼠心脏骤停后的脑血流量、梗死面积和神经元死亡，并测试这些效应在HOI-/-小鼠中是否显著降低。然后，我们将确定EGb诱导的HO 1表达变化是否会导致WT和HOI-/-小鼠神经元培养物中铁稳态和细胞存活的变化。为了进一步阐明可能的细胞作用机制，将使用WT和HOI-/-小鼠的原代培养神经元检测其对血红素毒性的易感性及其在控制铁流出中的作用。这些结果应该表明，如果EGb预处理可以保护铁毒性和细胞死亡，如果这种保护被取消在HOI-/-细胞。总之，我们将测试这一新的假设，一些有益的影响归因于银杏叶提取物可以归因于HO 1诱导本身及其生物学作用。这可能为银杏叶提取物在缺血和老年性痴呆中提供脑抵抗力的理论提供新的途径。

DESCRIPTION (provided by applicant): Ginkgo biloba extract (EGb 761 ; EGb) is a standardized extract and one of the most renowned natural compounds specifically to treat neurological conditions. The constituents from the extract are likely to have synergistic effects that have been shown to be protective against oxidative stress injury. However, the cellular mechanisms of protection afforded by Ginkgo biloba are still unclear. We tested the hypothesis that the neuroprotective action of EGb could be due partially to an induction of heme oxygenase 1 (HO1). We and others have reported that modulation of HO activity may well have direct physiological implications in stroke and in Alzheimer disease. Through the use of cultured neurons, we demonstrated that EGb induces HO1 in a dose-dependent manner. Interestingly, our preliminary results indicate that pre-treatment of primary neurons with EGb followed by washing out the cells and then inducing toxicity, either by H202 or glutamate, EGb revealed neuroprotection. This effect is abolished with the heme oxygenase inhibitor (SnPPIX). We are proposing that several of the protective effects of EGb in ischemic conditions could be mediated through beneficial actions of heme degradation and its metabolites. We will first determine the cerebral blood flow, the infarct size, and the neuronal death following cardiac arrest in EGb-treated WT mice and test whether these effects are significantly decreased in the HOI-/- mice. Then, we will determine whether EGb-induced changes in HO1 expression result in changes in iron homeostasis and cell survival in neuronal cultures derived from WT and HOI-/- mice. To further address possible cellular mechanisms of action, primary cultured neurons derived from WT and HOI-/- mice will be used to test their susceptibility to heme toxicity and their role in controlling the iron efflux. These results should indicate if EGb pretreatment can be protective against iron toxicity and cell death and if this protection is abolished in HOI-/- cells. Together, we will test this new hypothesis that some of the beneficial effects attributed to EGb could be attributed to HO1 induction itself and its biological actions. It could provide new pathways to support the theory that EGb could provide brain's resistance in conditions of ischemia and aged-related dementia.