作者:Vladimir Stepanov、Shotaro Miura、Akihiro Takano、Nahid Amini、Ryuji Nakao、Tomoaki Hasui、Kosuke Nakashima、Takahiko Taniguchi、Haruhide Kimura、Takanobu Kuroita、Christer Halldin
DOI:10.1002/jlcr.3284
日期:2015.5.15
Phosphodiesterase 10A (PDE10A) is a member of the PDE family of enzymes that degrades cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). Our aim was to label a series of structurally related PDE10A inhibitors with carbon-11 and evaluate them as potential positron emission tomography (PET) radioligands for PDE10A using nonhuman primates. The series consisted of seven compounds based on the 3-(1H-pyrazol-5-yl)pyridazin-4(1H)-one backbone. These compounds were selected from the initial larger library based on a number of parameters such as affinity, selectivity for hPDE10A in in vitro tests, lipophilicity, and on the results of multidrug resistance protein 1 (MDR1)-LLCPK1 and the parallel artificial membrane permeability assays. Seven radioligands (KIT-1, 3, 5, 6, 7, 9, and 12) were radiolabeled with carbon-11 employing O-methylation on the hydroxyl moiety using [11C]methyl triflate. In vivo examination of each radioligand was performed using PET in rhesus monkeys; analysis of radiometabolites in plasma also was conducted using HPLC. All seven radioligands were labeled with high (>90%) incorporation of [11C]methyl triflate into their appropriate precursors and with high specific radioactivity. Carbon-11 labeled KIT-5 and KIT-6 showed high accumulation in the striatum, consistent with the known anatomical distribution of PDE10A in brain, accompanied by fast washout and high specific binding ratio. In particular [11C]KIT-6, named [11C]T-773, is a promising PET tool for further examination of PDE10A in human brain.
磷酸二酯酶 10A (PDE10A) 是 PDE 家族中的一种酶,能降解环磷酸腺苷 (cAMP) 和环磷酸鸟苷 (cGMP)。我们的目的是用碳-11 标记一系列结构相关的 PDE10A 抑制剂,并利用非人灵长类动物对它们作为 PDE10A 的潜在正电子发射断层扫描 (PET) 放射配体进行评估。该系列包括基于 3-(1H-吡唑-5-基)哒嗪-4(1H)-酮骨架的七个化合物。这些化合物是从最初的大型化合物库中挑选出来的,挑选的依据包括亲和力、体外测试中对 hPDE10A 的选择性、亲脂性以及多药耐药蛋白 1 (MDR1)-LLCPK1 和平行人工膜渗透性试验的结果。七种放射性配体(KIT-1、3、5、6、7、9 和 12)通过使用 [11C]methyl triflate 对羟基上的 O-甲基化进行碳-11 放射性标记。利用正电子发射计算机断层显像技术对恒河猴体内的每种放射性配体进行了检测;还利用高效液相色谱法对血浆中的放射性代谢物进行了分析。所有七种放射性配体都标记了[11C]甲基三氟甲烷,其相应前体的[11C]甲基三氟甲烷掺入率很高(大于 90%),而且具有很高的特异性放射性。碳-11标记的KIT-5和KIT-6在纹状体中显示出较高的蓄积,这与已知的PDE10A在大脑中的解剖分布一致,同时还伴有快速洗脱和高特异性结合率。特别是[11C]KIT-6(命名为[11C]T-773),是进一步研究人脑中 PDE10A 的一种很有前途的 PET 工具。