Disruption of Purkinje cell function prior to huntingtin accumulation and cell loss in an animal model of Huntington Disease
Disruption of Purkinje cell function prior to huntingtin accumulation and cell loss in an animal model of Huntington Disease
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DOI：
10.1016/j.expneurol.2012.04.015
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发表时间：
2012-07-01
影响因子：
5.3
通讯作者：
Cowell, R. M.
中科院分区：
文献类型：
--
作者：
Dougherty, S. E.;Reeves, J. L.;Cowell, R. M.
亨廷顿病（HD）是一种破坏性的神经系统疾病，其特征在于精神、运动和认知功能的进行性恶化。浦肯野细胞（PC），小脑皮质的输出神经元，已被发现是脆弱的多重CAG重复障碍，但很少有人知道的参与PC功能障碍在HD。为了研究可能的PC异常，我们进行了定量真实的时间PCR，蛋白质印迹分析和免疫组化实验，以探讨PC标志物在R6/2小鼠严重HD模型中的变化。钙结合蛋白小清蛋白和钙结合蛋白以及谷氨酸脱羧酶67的转录物和蛋白质水平都有所降低。免疫组织化学支持这些结果，最实质性的变化发生在PC层。为了确定PC标志物表达的减少是否是由于细胞损失，我们对症状前和终末期R6/2小鼠进行了体视学研究。体视学计数表明，到终末期，PC数量显着减少，但症状前动物（4周龄）没有变化。为了评估细胞损失和症状发作之前的细胞功能，我们测量了来自4周龄动物的PC中的自发放电，并发现PC放电中的显著缺陷，如尖峰率降低57%所示。有趣的是，直到12周龄才在PC中广泛观察到亨廷顿蛋白包涵体，这表明可溶性亨廷顿蛋白和/或其他细胞类型的异常可能导致PC功能障碍。考虑到PC在运动控制中的作用，这些数据表明，早期PC功能障碍可能导致该HD模型中的运动障碍。(C)2012 Elsevier Inc. All rights reserved.
Huntington Disease (HD) is a devastating neurological disorder characterized by progressive deterioration of psychiatric, motor, and cognitive function. Purkinje cells (PCs), the output neurons of the cerebellar cortex, have been found to be vulnerable in multiple CAG repeat disorders, but little is known about the involvement of PC dysfunction in HD. To investigate possible PC abnormalities, we performed quantitative real time PCR, Western blot analysis, and immunohistochemistry experiments to explore the changes in PC markers in the R6/2 mouse model of severe HD. There were reductions in the transcript and protein levels of the calcium-binding proteins parvalbumin and calbindin, as well as the enzyme glutamic acid decarboxylase 67. Immunohistochemistry supported these results, with the most substantial changes occurring in the PC layer. To determine whether the reductions in PC marker expression were due to cell loss, we performed stereology on both presymptomatic and end-stage R6/2 mice. Stereological counts indicated a significant reduction in PC number by end-stage but no change in presymptomatic animals (4 weeks of age). To assess cellular function prior to cell loss and symptom onset, we measured spontaneous firing in PCs from 4-week old animals and found a striking deficit in PC firing as indicated by a 57% decrease in spike rate. Interestingly, huntingtin inclusions were not widely observed in PCs until 12 weeks of age, indicating that soluble huntingtin and/or abnormalities in other cell types may contribute to PC dysfunction. Considering the roles for PCs in motor control, these data suggest that early PC dysfunction potentially contributes to motor impairment in this model of HD. (C) 2012 Elsevier Inc. All rights reserved.