NMR STUDIES OF TRANSGENIC MOUSE MODELS OF HUNTINGTONS DISEASE & ALS

该项目需要测量代谢物水平（"H"和 "C）在转基因小鼠的脑提取物中， 肌萎缩侧索硬化症（ALS）和亨廷顿病（HD）。 这些代谢物水平，然后用于补充体内 使用MRS测定许多相同的化学品。我们的目标是 确定TCA循环代谢是否存在缺陷， 神经胶质细胞周期的变化。 谷氨酸水平升高 通常与ALS有关，并且NAA的显著降低通常 看HD。 我们使用体内磁共振波谱（4.7T）对小鼠进行纵向研究 在MGH），然后在不同的时间间隔提取大脑， 使用体外NMR光谱法在500 MHz下进行的研究 实验室 从这些提取物中，我们确定了 使用1D和2D质子光谱分析代谢物浓度。 我们 还利用直接和间接观察碳-13光谱， 测定来自小鼠的TCA循环代谢物的富集分数 在处死前输注标记的葡萄糖。 这些也是 与在图1中获得的体内动态碳-13光谱相比， 局部脑区 然后将NMR数据与HPLC相关联 测量一些相同的化合物，以确定准确性 并提供结果的绝对量化 代谢物水平。 此外，我们还进行了组织化学和 在相同的动物上进行组织学检查，以确定 生化缺陷与其他神经病理学变化。 结果 到目前为止，我们所获得的结果表明， 尽管事实上， 组织学显示很少神经元损失。 此外还有 这些小鼠中谷氨酸-谷氨酰胺循环的严重失衡。 的 NAA干扰随时间呈指数级发展。 在ALS小鼠中， 相反，我们发现NAA代谢的变化很小， 发现谷氨酸盐大量增加。 这些结果清楚地表明 核磁共振光谱学有可能产生有价值的见解， 这些疾病的基本生化病因学。

This project entails measurement of metabolite levels (both 'H and "C) in brain extracts of transgenic mice that are models for amyotrophic lateral sclerosis (ALS) and Huntington's disease (HD). These metabolite levels are then used to complement in vivo determination of many of the same chemicals using MRS. Our goal is to determine if there are defects in TCA cycle metabolism and neuronal-glial cycling in these mice. Elevated glutamate levels have often been implicated in ALS and profound decreases in NAA are often seen in HD. We study the mice longitudinally using in vivo MRS (4.7T at MGH) and then take extracts of brains at various time intervals for study using in vitro NMR spectroscopy at 500 MHz at the Magnet Laboratory. From these extracts, we determine the absolute concentrations of metabolites using 1D and 2D proton spectroscopy. We also utilize direct and indirect observe carbon-13 spectroscopy to determine fractional enrichements of TCA cycle metabolites from mice infused with labeled glucose prior to sacrifice. These are also compared to the in vivo dynamic carbon-13 spectroscopy obtained in localized brain regions. The NMR data is then correlated with HPLC measurements of some of the same compounds to ascertain the accuracy of the results and to provide absolute quantification of the metabolite levels. In addition, we have performed histochemistry and histology on the same animals to determine the correlation of the biochemical defects with other neuropathological changes. The results we have obtained so far indicate a profound disturbance of NAA metabolism in the neurons of the HD animals in spite of the fact that histology shows very little neuronal loss. In addition, there is a profound imbalance in glutamate-glutamine cycling in these mice. The NAA disturbance progresses exponentially over time. In the ALS mice, in contrast, we have found very small changes in NAA metabolism while finding large increases in glutamate. These results clearly indicate that NMR spectroscopy has the potential to yield valuable insight intoi the basic biochemical etiology of these diseases.