Novel neurotrophic therapy in a mouse model of ALS

描述（由申请人提供）： 肌萎缩侧索硬化症（ALS）是一种神秘的神经退行性疾病，其特征在于运动神经元的选择性丧失，导致快速进行性运动无力和由于呼吸衰竭而导致的早期死亡。ALS中神经变性的病因尚不清楚，但可能是由多种机制的组合引起的，包括蛋白质错误折叠、线粒体功能障碍、氧化损伤、轴突运输缺陷、兴奋性毒性、生长因子信号传导缺陷和炎症。最近的一份报告显示，SOD 1 mu介导的内皮损伤在运动神经元变性之前发生，随后发生神经血管炎症反应，表明内皮损伤是疾病发生的关键因素。 7，8-二羟基黄酮（7，8-DHF）是黄酮家族的成员。存在于水果和蔬菜中的黄酮类化合物已被证明具有多种生物学作用，包括神经保护、抗氧化和抗凋亡特性。已经表明，类黄酮改善了空间记忆，并且这种效果与小鼠海马齿状回中血管生成和神经元棘密度增加有关。此外，空间记忆的改善与运动相结合得到增强。黄酮类化合物通过与包括PI 3 K/Akt在内的信号通路相互作用，对学习和记忆相关的长时程增强作用发挥作用，从而影响记忆和认知表现。最近，7，8-DHF显示出与TrkB受体的高亲和力结合，并引起其二聚化和自磷酸化，导致下游信号级联激活。在小鼠中全身施用该化合物基本上激活脑中的TrkB，抑制神经元细胞死亡，以TrkB依赖性方式减少中风中的梗塞体积，并且在帕金森病和中风的动物模型中具有神经保护作用。这些数据表明，7，8-二羟基黄酮显示出其作为有效和选择性TrkB激动剂的作用，其通过激活类似的信号传导机制来模拟BDNF的生化和生理作用。7，8-二羟基黄酮的药理作用提示其可能成为治疗神经系统疾病的有效药物。我们将监测7，8-DHF给药对体重、运动性能和寿命的影响，并使用组织病理学、神经化学技术和磁共振成像（MRI）在死后和体内检查对运动神经元和腹角大小、数量、树突分支、棘密度变化的影响。此外，在ALS小鼠中使用磁共振光谱法检测神经元健康的神经化学标志物（N-乙酰天冬氨酸）和神经胶质标志物（肌肌醇、牛磺酸）。我们将使用ALS小鼠脊髓的体内MRI进一步评估血液脊髓屏障的变化。我们将使用神经化学技术来测量BDNF，并使用神经病理学/体视学技术来量化脊髓中的生物标志物。 我们提出的新研究将产生数据，以提高我们对疾病机制的理解，并测试7，8-DHF在ALS中的有益作用。

DESCRIPTION (provided by applicant): Amyotrophic lateral sclerosis (ALS) is an enigmatic neurodegenerative disorder characterized by the selective loss of motor neurons that results in rapid progressive motor weakness and early death due to respiratory failure. The etiology of neurodegeneration in ALS is not known but likely arises from a combination of mechanisms, including protein misfolding, mitochondria dysfunction, oxidative damage, defective axonal transport, excitoxicity, deficient growth factor signaling, and inflammation. A very recent report shows that SOD1 mutant-mediated endothelial damage develops before motor neuron degeneration followed later by a neurovascular inflammatory response suggesting that endothelial damage is a key contributor to disease initiation. 7,8-dihydroxyflavone (7,8-DHF) is a member of the flavonoid family. Flavonoids, present in fruits and vegetables, have been shown to exert diverse biological actions including neuroprotective, anti-oxidant and anti-apoptotic properties. It has been shown that flavonoids improved spatial memory and this effect was associated with increased angiogenesis and neuronal spine density in the dentate gyrus of the hippocampus in mice. Furthermore, improvement in spatial memory was enhanced in combination with exercise. Flavonoids exert effects on long-term potentiation underlying learning and memory, on and consequently memory and cognitive performance, through their interactions with the signaling pathways including PI3K/Akt. Most recently, 7,8-DHF was shown to bind with high affinity to the TrkB receptor and provoke its dimerization and autophosphorylation, leading to downstream-signaling cascade activation. Systemic administration of this compound in mice substantially activates TrkB in the brain, inhibits neuronal cell death, decreases infarct volumes in stroke in a TrkB-dependent manner, and is neuroprotective in an animal model of Parkinson's disease and stroke. This data indicate that 7,8-dihydroxyflavone shows it's effects as a potent and selective TrkB agonists that virtually mimic BDNF's biochemical and physiological actions by activating similar signaling mechanism. The effects of 7,8-dihydroxyflavone suggest that it could be a powerful therapeutic drug for the treatment of neurological diseases. We will monitor the effects of 7,8-DHF administration on body weight, motor performance and longevity and examine the effects on motor neuron and ventral horn changes in size, number, dendritic branching, spine density using histopathological, neurochemical techniques and magnetic resonance imaging (MRI) post mortem and in vivo. In addition neurochemical markers for neuronal health (N- acetylaspartate) and glial markers (myo-inosotol, taurine) will be detected using magnetic resonance spectroscopy in ALS mice. We will further evaluate blood spinal cord barrier changes using in vivo MRI of the spinal cord in the ALS mice. We will use neurochemical techniques to measure BDNF, and neuropathological/stereological techniques to quantify biomarkers in the spinal cord. The novel studies we propose will produce data to improve our understanding of disease mechanisms and test the beneficial effects of 7,8-DHF in ALS.