<sup>11</sup>C-Labeled Radiotracer for Noninvasive and Quantitative Assessment of the Thiocyanate Efflux System in the Brain
作者:Toshimitsu Okamura、Satoshi Tsukamoto、Maki Okada、Tatsuya Kikuchi、Ryutaro Aizawa、Hidekatsu Wakizaka、Nobuki Nengaki、Masanao Ogawa、Hideki Ishii、Ming-Rong Zhang
DOI:10.1021/acs.bioconjchem.2c00277
日期:2022.9.21
Thiocyanate (SCN–) alters the potency of certain agonists for the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor, and dysfunctions in AMPA receptor signaling are considered to underlie a number of neurological diseases. While humans may be exposed to SCN– from the environment, including food sources, a carrier-mediated system transports SCN– from the brain into the blood and is an important regulator of SCN– distribution in the central nervous system. The assessment of this SCN– efflux system in the brain would thus be useful for understanding the mechanisms underlying the neurotoxicity of SCN– and for elucidating the relationship between the efflux system and brain diseases. However, the currently available technique for studying SCN– efflux is severely limited by its invasiveness. Here, we describe the development of a SCN– protracer, 9-pentyl-6-[11C]thiocyanatopurine ([11C]1), to overcome this limitation. [11C]1 was synthesized by the reaction of the iodo-precursor and [11C]SCN– or the reaction of the disulfide precursor with [11C]NH4CN. The protracer [11C]1 entered the brain after intravenous injection into mice and was rapidly metabolized to [11C]SCN–, which was then eliminated from the brain. The efflux of [11C]SCN– was dose-dependently inhibited by perchlorate, a monovalent anion, and the highest dose caused an 82% reduction in the efflux rate. Our findings demonstrate that [11C]1 can be used for the noninvasive and quantitative assessment of the SCN– efflux system in the brain.
硫氰酸根(SCN-)会改变某些激动剂对α-氨基-3-羟基-5-甲基-4-异恶唑丙酸(AMPA)受体的效力,而AMPA受体信号传导障碍被认为是许多神经系统疾病的基础。虽然人类可能会从环境中(包括食物来源)接触到SCN-,但载体介导系统会将SCN-从大脑运送到血液中,是SCN-在中枢神经系统分布的重要调节器。因此,评估大脑中的这种SCN-外排系统对于理解SCN-神经毒性的机制以及阐明外排系统与脑部疾病之间的关系非常有用。然而,目前用于研究SCN-外排的技术因其侵入性而受到严重限制。在此,我们描述了一种SCN-探针9-戊基-6-[11C]硫氰酸嘌呤([11C]1)的开发,以克服这一限制。[11C]1是通过碘前体与[11C]SCN-的反应或二硫键前体与[11C]NH4CN的反应合成的。探针[11C]1静脉注射到小鼠体内后进入大脑,并迅速代谢为[11C]SCN-,然后从大脑中排出。高氯酸盐(一种一价阴离子)对[11C]SCN-