Evaluation of Rho-Kinase Activity in Mice Brain Using N-[11C]Methyl-hydroxyfasudil with Positron Emission Tomography
Evaluation of Rho-Kinase Activity in Mice Brain Using N-[11C]Methyl-hydroxyfasudil with Positron Emission Tomography
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DOI：
10.1007/s11307-013-0695-y
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发表时间：
2014-06
影响因子：
3.1
通讯作者：
J. Taniguchi;C. Seki;H. Takuwa;H. Kawaguchi;Y. Ikoma;Masayuki Fujinaga;I. Kanno;Ming-Rong Zhang;S. Kuwabara;Hiroshi Ito
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文献类型：
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作者：
J. Taniguchi;C. Seki;H. Takuwa;H. Kawaguchi;Y. Ikoma;Masayuki Fujinaga;I. Kanno;Ming-Rong Zhang;S. Kuwabara;Hiroshi Ito
PurposeRho 是一种小分子量 GTP 结合蛋白，充当活性（GTP 结合）和非活性（GDP 结合）状态之间的分子穿梭开关。已知 Rho 通过肌动蛋白细胞骨架重组参与细胞运动、细胞粘附和胞质分裂。 Rho 的 GTP 结合形式与其特定的下游靶点相互作用，触发细胞内信号级联反应。 Rho 效应子（例如 Rho 激酶）已根据其与 Rho 的 GTP 结合形式的选择性结合而被分离出来。 Rho-激酶被认为在多种神经系统疾病的发病机制中具有重要作用，因为在多种中枢神经系统疾病中观察到Rho/Rho-激酶途径的激活。先前的组织化学研究已表明 Rho 激酶调节的多种分子机制。由于缺乏适当的放射性示踪剂，Rho/Rho 激酶的神经影像学很少被研究。最近，N-[11C]甲基-羟基法舒地尔，一种用于正电子发射断层扫描（PET）的新型放射性示踪剂，已被引入测量Rho激酶活性。本研究对N-[11C]甲基羟基法舒地尔在小鼠脑内的区域分布和动力学进行了研究。程序静脉输注N-[11C]甲基羟基法舒地尔后进行90分钟的动态扫描。结果N-[11C]甲基羟基法舒地尔的摄取在5分钟内达到最大值，并在各器官中逐渐减少。 30至60分钟期间脑、肝脏和肾脏的标准摄取值（SUV）平均为0.17±0.03、0.76±0.18和0.62±0.18，60至90分钟期间为0.15±0.01，分别为0.69±0.33和0.64±0.17。N-[11C]甲基羟基法舒地尔在整个大脑中广泛分布，放射性水平较低。注射 N-[11C]甲基-羟基法舒地尔后 90 分钟血浆中的放射性浓度导致对照和法舒地尔预处理的 SUV 分别为 0.0013 和 0.0023±0.0008。与正常对照小鼠相比，在法舒地尔预处理的小鼠中观察到约两倍高的放射性浓度。在冷性脑损伤小鼠模型中，损伤部位的N-[11C]甲基羟基法舒地尔蓄积量略高于对照部位，且“损伤后24小时”组差异有统计学意义（P< 0.05）。结论这些结果表明，脑损伤后，N-[11C]甲基羟基法舒地尔与Rho激酶的活性形式结合。使用 N-[11C]甲基-羟基法舒地尔进行 PET 成像可以为各种神经系统疾病的病理生理学提供新的见解，包括中风、炎症性疾病、脱髓鞘疾病、阿尔茨海默病和神经性疼痛。
PurposeRho is a small molecular weight GTP-binding protein and works as a molecular shuttling switch between an active (GTP-bound) and inactive (GDP-bound) state. Rho is known to be involved in cell motility, cell adhesion, and cytokinesis through actin cytoskeleton reorganization. The GTP-bound form of Rho interacts with its specific downstream target, triggering intracellular signaling cascades. Rho effectors such as Rho-kinases have been isolated on the basis of their selective binding to the GTP-bound form of Rho. Rho-kinase is thought to have an important role in the pathogenesis of a variety of neurological diseases because activation of the Rho/Rho-kinase pathway has been observed in various central nervous system disorders. Previous histochemical studies have shown multiple molecular mechanisms for the regulation of Rho-kinase. Neuroimaging of Rho/Rho-kinase has rarely been studied because of a lack of appropriate radiotracers. Recently,N-[11C]methyl-hydroxyfasudil, a new radiotracer for positron emission tomography (PET), has been introduced to measure Rho-kinase activity. In this study, the regional distribution and kinetics ofN-[11C]methyl-hydroxyfasudil were investigated in the brains of mice.ProceduresA 90-min dynamic scan was performed following intravenous infusion ofN-[11C]methyl-hydroxyfasudil.ResultsThe uptake ofN-[11C]methyl-hydroxyfasudil reached a maximum within 5 min and gradually decreased in all organs. The standard uptake values (SUVs) in the brain, liver, and kidney on average between 30 to 60 min were 0.17 ± 0.03, 0.76 ± 0.18, and 0.62 ± 0.18 and from 60 to 90 min were 0.15 ± 0.01, 0.69 ± 0.33, and 0.64 ± 0.17, respectively.N-[11C]Methyl-hydroxyfasudil showed a widespread distribution throughout the brain, with low levels of radioactivity. Radioactivity concentration in plasma at 90 min after injection ofN-[11C]methyl-hydroxyfasudil resulted in SUVs in the control and fasudil pretreatment of 0.0013 and 0.0023 ± 0.0008, respectively. Compared to normal control mice, about twofold higher radioactivity concentration was observed in fasudil-pretreated mice. In a cold brain injury mouse model, accumulation ofN-[11C]methyl-hydroxyfasudil was slightly higher at the injury site than that at the control site, and the difference was statistically significant in the “24 h after injury” group (P< 0.05).ConclusionsThese results suggest that following brain injury,N-[11C]methyl-hydroxyfasudil binds to the active form of Rho-kinase. PET imaging usingN-[11C]methyl-hydroxyfasudil could provide new insights into the pathophysiology of a variety of neurological disorders including stroke, inflammatory diseases, demyelinating diseases, Alzheimer's disease, and neuropathic pain.