In Vivo Testing of Microtubule-Stabilizing Drugs in Triple Transgenic Mice

描述（由申请人提供）：我们的长期目标是开发新的治疗药物，通过保持细胞骨架的完整性来减缓阿尔茨海默病（AD）中t神经原纤维病理的发展。基于阿尔茨海默病大脑和暴露于Ab原纤维的神经元中观察到的明显的神经元营养不良和微管（MT）完整性破坏，我们测试了MT稳定药物（如紫杉醇）对Ab毒性的保护作用。紫杉醇和其他几种mt稳定药物显著提高了培养中经ab处理的神经元的存活率。然而，这些药物不会进入大脑，因此无法在AD的小鼠体内模型中进行测试。我们已经合成了两种新的化合物，可以在培养中保护神经元，并实际上穿过血脑屏障（BBB）。药物的半衰期和脑分布的药代动力学研究已经完成，有限的毒性实验也已经完成。该项目的目标是使用最近开发的具有Ab和t病理的三重转基因小鼠模型（3xTg-AD）进行体内概念验证研究。具体目的是：(1)确定两种药物在长期给药数周的对照小鼠中的最大耐受剂量；(2)通过观察小鼠长期给药期间的行为表现，验证3xTg-AD小鼠模型中经脑紫杉烷Tx-67和非紫杉烷mt相互作用药物GS-164的体内效应；(3)评估Tx-67或GS-164慢性治疗对3xTg-AD mic中ad样神经病变进展的体内影响。接受药物治疗的小鼠将与只接受生理盐水注射的对照动物进行比较。在整个治疗期间，行为测试将每两周进行一次。将使用标准的神经病理学、免疫组织化学和生化策略分析大脑淀粉样蛋白和t病变的指标。基于我们对培养原代神经元的体外研究和最近的一篇报道，紫杉醇逆转了脑损伤小鼠脊髓神经元的外周轴突运输缺陷，我们预计该药物将缓解3xTg-AD小鼠的脑病理。我们已经确定的药物使我们有可能提供大脑渗透的mt稳定药物的体内评估，因为它们有可能减缓大脑中ad样神经病理学的进展。如果这些药物确实能改变任何认知变化的进展和/或脑损伤的积累，这些发现将支持进一步研究这种非常新颖的治疗策略，以减缓老年痴呆症等年龄依赖性神经变性。

DESCRIPTION (provided by applicant): Our long-term goal is to develop novel therapeutic agents targeted to slowing the development of t neurofibrillary pathology in Alzheimer's disease (AD) by preserving the integrity of the cytoskeleton. Based on the pronounced neuronal dystrophy and disruption of microtubule (MT) integrity observed in AD brain and neurons exposed to Ab fibrils, we have tested the effects of MT-stabilizing drugs such as Taxol for protection against Ab toxicity. Taxol and several other MT-stabilizing drugs markedly enhanced survival of Ab-treated neurons in culture. However, these drugs do not enter the brain and thus cannot be tested in an in vivo mouse model for AD. We have synthesized two novel compounds that protect neurons in culture and actually cross the blood brain barrier (BBB). Pharmacokinetic studies on the half-lives and the brain distribution of the drugs have already been completed, as have limited toxicity experiments. The goal of this project is to use a recently developed triple transgenic mouse model (3xTg-AD) with both Ab and t pathology to conduct an in vivo proof-of concept study. The Specific Aims are: (1) to determine the maximal tolerated doses of the two drugs in control mice receiving chronic administration for several weeks; (2) to test the in vivo effects of the brain permeant taxane Tx-67 and the non-taxane MT-interacting drug GS-164 in the 3xTg-AD mouse model by assessing the behavioral performance of the mice throughout the period of chronic drug administration; and (3) to evaluate the in vivo effects of chronic treatment with Tx-67 or GS-164 on the progression of the AD-like neuropathological lesions that develop in the 3xTg-AD mic. Drug-treated mice will be compared with control animals receiving only saline injections. Behavioral testing will be done bi-weekly throughout the treatment period. Brains will be analyzed for indicators of both amyloid and t lesions using standard neuropathological, immuno-histochemical, and biochemical strategies. Based on our in vitro studies with primary neurons in culture and a recent report that Taxol reversed peripheral axonal transport deficits in spinal cord neurons of a tauopathy mouse, we anticipate the drugs will moderate the brain pathology in the 3xTg-AD mice. The drugs we have identified make it possible for us to provide the very first in vivo evaluation of brain permeant MT-stabilizing drugs for their potential to slow the progression of AD-like neuropathology in the brain. If the drugs do indeed alter the progression of any cognitive changes and/or the accumulation of the brain lesions, the findings would support further investigation into this very novel therapeutic strategy for slowing age-dependent neurodegeneration such as occurs in AD.