Preclinical neuroprotective trials of a PPAR-gamma agonist in HD mouse models

描述(申请人提供)：亨廷顿病(HD)是一种神经退行性疾病，由亨廷顿蛋白基因中CAG重复序列的病理性延长引起。目前还没有治疗方法可以延缓人类疾病的发病和/或延缓疾病的发展。转录调控失调和线粒体功能障碍与HD的发病机制密切相关。过氧化物酶体增殖物激活受体(PPAR)是配体激活的转录因子核激素受体家族的成员。PPAR？激活可以防止神经元退化，并伴随着线粒体活性的增加。最近的研究也提供了PPAR？激动剂在HD细胞模型中具有神经保护作用并增加线粒体功能。我们的初步研究表明，突变的亨廷顿蛋白改变了PPAR？HD细胞模型和小鼠模型中PPAR？激动剂罗格列酮在细胞模型中保护细胞免受亨廷丁突变诱导的细胞死亡，并在HD小鼠模型中延长存活时间。因此，我们建议确定PPAR？激活以改善突变的亨廷顿蛋白在体内引起的病理和功能障碍。在目标1中，我们将确定PPAR-γ激动剂罗格列酮在片段突变亨廷丁转基因小鼠模型(N171-82Q小鼠)中的量效关系和对疾病发生和发展的影响。我们将长期给N171-82Q HD小鼠三个剂量的罗格列酮(10，20，40 mg/kg/d，ip)。症状前试验在6周龄开始注射药物，症状试验在12周龄开始注射药物。运动行为表现将通过加速转杆装置进行评估。罗格列酮对脑萎缩的影响将在6、12和18周龄症状前试验和16、20周龄症状试验时进行纵向结构磁共振检查。疾病的发生将通过第一次检测到的旋转棒缺陷来评估。药物浓度将用高效液相色谱/质谱仪测定，罗格列酮对脑组织病理改变的影响也将通过组织学分析来评估。在目的2中，我们将确定罗格列酮对亨廷顿蛋白转基因小鼠模型(BACHD小鼠)运动功能和脑病理的影响。我们将在BACHD小鼠出现运动障碍之前和之后长期给予最佳剂量的罗格列酮。运动行为表现将通过旋转杆装置进行评估。脑萎缩将在6个月和12个月时进行MRI检查，神经病理学将在12个月时进行组织学检查。拟议的研究将为PPAR的进一步临床试验提供关键证据。人体内的激动剂。我们的长期目标是为HD患者开发有效的治疗药物。 公共卫生意义：亨廷顿病(HD)是影响人类神经系统的最常见的遗传性疾病，与其他神经退行性疾病有许多相似之处。没有治愈的方法，也没有有效的治疗方法来推迟HD的发病或减缓其进展。我们建议的研究将检验临床批准的PPAR的效果？激动剂在HD小鼠模型中的疾病发生和进展，并导致开发HD治疗方法的策略。

DESCRIPTION (provided by applicant): Huntington disease (HD) is a neurodegenerative disease that is caused by the pathological elongation of the CAG repeats in the huntingtin gene. There is no treatment to delay onset and/or slow down the progression of disease in humans. Transcriptional dysregulation and mitochondrial dysfunction have been strongly implicated in the pathogenesis of HD. Peroxisome proliferator- activated receptors (PPARs) are members of the nuclear hormone receptor family of ligand- activated transcription factors. PPAR? activation prevents neuronal degeneration with a concomitant increase in mitochondrial viability. Recent studies have also provided evidence that PPAR? agonists are neuroprotective and increase mitochondrial function in a cell model of HD. Our preliminary studies indicated that mutant huntingtin altered the PPAR? levels in both cell models and mouse model of HD, and PPAR? agonist rosiglitazone protected cells against mutant huntingtin-induced cell death in cell models and extended survival in a HD mouse model. Therefore, we propose to determine the possibility of PPAR? activation to ameliorate mutant huntingtin-induced pathology and dysfunction in vivo. In Aim 1, we will determine the dose response and effect of PPAR-gamma agonist rosiglitazone on disease onset and progression in a fragment mutant huntingtin transgenic mouse model (N171-82Q mice). We will chronically administer three doses of rosiglitazone (10, 20, 40 mg/kg/day, i.p) to N171-82Q HD mice. Drug injection will be started at 6 weeks of age for presymptomatic trials and at 12 weeks of age for symptomatic trials. Motor behavioral performance will be assessed by accelerating rotarod apparatus. Effect of rosiglitazone on brain atrophy will be examined longitudinally by using structural MRI at 6, 12 and 18 weeks of age for presymptomatic trials and at 16, 20 weeks for symptomatic trials. The onset of disease will be evaluated by first detectable rotarod deficit. Drug concentrations will be measured by HPLC/MS/MS. Effect of rosiglitazone on brain pathological change will be also evaluated by histological analysis. In Aim 2, we will determine the effect of rosiglitazone on motor function and brain pathology in a full-length mutant huntingtin transgenic mouse model (BACHD mice). We will chronically administer optimal dose of rosiglitazone to BACHD mice before onset and after onset of motor deficit. Motor behavioral performance will be assessed by rotarod apparatus. Brain atrophy will be examined by using MRI at 6 and 12 months of age and neuropathology will be examined by histology at 12 months. The proposed study will provide critical evidence for further clinical trials of PPAR? agonists in humans. Our long-term goal is to develop effective therapeutic agents for HD patients. PUBLIC HEALTH RELEVANCE: Huntington's disease (HD) is the most common inherited disorder affecting the nervous system in humans and shares many features with other neurodegenerative diseases. There is no cure, nor are there effective treatments that delay the onset or slow down the progression of HD. Our proposed studies will examine the effect of a clinical approved PPAR? agonist on disease onset and progression in mouse models of HD and result in a strategy to develop therapeutics for HD.