Cerebral Metabolic Flux Mapping Using Oxygen 17 NMR

氧是最丰富的元素之一，几乎存在于所有与生物相关的分子中。在……里面 过去的核磁共振活性同位素17O受到的关注很少，这是因为弛豫时间短和低 敏感度。然而，随着更高磁场强度的可用，富含17O的衬底的使用 和有利的T2 */T1比率，任何敏感性问题都可以快速克服，允许收购3D 几秒钟内的MRSI数据。此外，广泛的化学位移分散允许检测到 代谢物种类繁多。在这里，我们建议将17O核磁共振与富含17O的底物相结合 注入一种快速、灵敏和稳健的方法，以在活体内绘制大鼠大脑中的代谢通量。 1、2或3位富含17O-葡萄糖的代谢提供了糖酵解、三羧酸的信息 循环或丙酮酸脱氢酶活性分别。星形胶质细胞代谢与丙酮酸羧基酶活性 可以用富含17O的醋酸盐和碳酸氢盐进行评估。每一家的17O周转特征 底物可以用代谢模型来描述，其中一些需要额外的输入，如再循环 170-来自其他器官的标记水。在这里，我们将开发按顺序测量所有必需输入的方法 以可靠地获得所需的代谢通量。在优化了17O基片的合成工艺后， 将在体外研究17O核磁共振和17O标记动力学的特征。建立的~1H-[~(13)C]-核磁共振 结合13C标记葡萄糖和2-脱氧葡萄糖输注的技术将用于验证 大鼠以170为基础的脑代谢分别通过三羧酸循环和糖酵解 脑在活体中的温度为11.7T。

Oxygen is one of the most abundant elements and is present in almost all biologically relevant molecules. In the past the NMR active isotope 17O has received little attention, due to short relaxation times and low sensitivity. However, with the availability of higher magnetic field strengths, the use of 17O-enriched substrates and the favorable T2 */T1 ratio, any sensitivity concerns are quickly overcome, allowing the acquisition of 3D MRSI data in the span of seconds. Furthermore, the wide chemical shift dispersion allows the detection of a wide range of metabolites. Here we propose to develop 17O NMR in combination with 17O-enriched substrate infusion into a fast, sensitive and robust method to spatially map metabolic fluxes in the rat brain in vivo. Metabolism of 17O-glucose enriched in the 1, 2 or 3 positions gives information on glycolytic, tricarboxylic acid cycle or pyruvate dehydrogenase activity, respectively. Astroglial metabolism and pyruvate carboxylase activity can be assessed with 17O-enriched acetate and bicarbonate. The 17O turnover characteristics of each substrate can be described by a metabolic model, some of which require additional inputs such as recirculated 17O-labeled water from other organs. Here we will develop the methods to measure all required inputs in order to reliably obtain the desired metabolic fluxes. Following the optimization of 17O substrate synthesis, the characteristics of 17O NMR and 17O label dynamics will be studied in vitro. The established 1H-[13C]-NMR technique in combination with 13C-labeled glucose and 2-deoxyglucose infusions will be used to validate the 17O-based cerebral metabolic fluxes through the tricarboxylic acid cycle and glycolysis, respectively, in the rat brain in vivo at 11.7 T.