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剂，其靶向通过保持细胞骨架的完整性来减缓阿尔茨海默病（AD）中神经系统病理学的发展。基于在AD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）完整性的破坏，我们已经测试了MT稳定药物（如紫杉醇）对保护免受Ab毒性的作用。紫杉醇和其他几种MT稳定药物显着提高了Ab处理的神经元在培养中的生存。然而，这些药物不进入大脑，因此不能在AD的体内小鼠模型中进行测试。我们已经合成了两种新的化合物，它们可以保护培养中的神经元，并实际上可以穿过血脑屏障（BBB）。关于药物半衰期和大脑分布的药代动力学研究已经完成，毒性实验也很有限。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。具体目标是：（2）通过评估小鼠在整个慢性药物给药期间的行为表现，测试脑渗透性紫杉烷Tx-67和非紫杉烷MT相互作用药物GS-164在3xTg-AD小鼠模型中的体内作用;和（3）评价用Tx-67或GS-164长期治疗对在3xTg-AD小鼠中发展的AD样神经病理学病变的进展的体内作用。将药物处理的小鼠与仅接受盐水注射的对照动物进行比较。在整个治疗期间，将每两周进行一次行为测试。将使用标准的神经病理学、免疫组织化学和生物化学策略分析大脑淀粉样蛋白和t病变的指标。基于我们对培养的原代神经元的体外研究和最近的一份关于紫杉醇逆转tau蛋白病小鼠脊髓神经元中外周轴突运输缺陷的报告，我们预计这些药物将减轻3xTg-AD小鼠的脑病理学。我们已经确定的药物使我们有可能提供脑渗透MT稳定药物的第一个体内评价，以减缓脑中AD样神经病理学的进展。如果这些药物确实改变了任何认知变化的进展和/或大脑病变的积累，这些发现将支持进一步研究这种非常新颖的治疗策略，以减缓年龄依赖性神经退行性疾病，如AD。

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.