Binding characteristics of radiofluorinated 6-dialkylamino-2-naphthylethylidene derivatives as positron emission tomography imaging probes for β-amyloid plaques in Alzheimer's disease
Binding characteristics of radiofluorinated 6-dialkylamino-2-naphthylethylidene derivatives as positron emission tomography imaging probes for β-amyloid plaques in Alzheimer's disease
复制标题
DOI：
10.1523/jneurosci.21-24-j0004.2001
复制
发表时间：
2001-12-15
影响因子：
5.3
通讯作者：
Barrio, JR
中科院分区：
文献类型：
--
作者：
Agdeppa, ED;Kepe, V;Barrio, JR
老年斑(SPS)和神经原纤维缠结(NFTs)是伴随着阿尔茨海默病(AD)神经退行性变的标志性病理改变，其中β-淀粉样蛋白(Aβ)肽是SPS的主要成分。我们的实验室以前开发了疏水性荧光分子成像探针2-(1-{6[(2-F-18]氟乙基)(甲基)氨基]-2-萘基}乙叉)丙二腈([F-18]FDDNP)，它可以跨越血脑屏障，确定AD患者体内SPS和NFTs的定位和负载。在本报告中，我们用荧光和放射性结合分析方法测定了FDDNP及其类似物1-{6-[(2-[F-18]氟乙基)(甲基)氨基]萘-2-基)乙酮([F-18]Fene)与Aβ(1-40)合成纤维的结合亲和力。FDDNP和Fene似乎都与Aβ(1-40)纤维上的两个动力学上可区分的结合位点结合。荧光滴定结果显示，FDDNP和Fene的高亲和力结合部位的表观K-d值分别为0.12和0.16 nM，低亲和力结合部位的表观K-d值分别为1.86和71.2 nM。传统的放射性结合分析也得到了低纳摩尔范围内的表观K-d值。FDDNP和Fene的两个动力学上可区分的结合位点的存在表明SPS有多个结合位点，并确定了允许这一家族探针在体内使用的结构优化的参数。这些探针与纤维上的多个结合位点的高亲和力结合与数字放射自显影、免疫组织化学和共聚焦荧光显微镜使用AD患者的人脑标本获得的结果一致。
Senile plaques (SPs) and neurofibrillary tangles (NFTs) are hallmark pathologies accompanying the neurodegeneration involved in Alzheimer's disease (AD), for which beta -amyloid (A beta) peptide is a major constituent of SPs. Our laboratories previously developed the hydrophobic, fluorescent molecular-imaging probe 2-(1-{6[( 2-[F-18] fluoroethyl)(methyl) amino]-2-naphthyl} ethylidene) malononitrile ([F-18] FDDNP), which crosses the blood-brain barrier and determines the localization and load of SPs and NFTs in vivo in AD patients. In this report, we used fluorimetric and radioactive binding assays to determine the binding affinities of FDDNP and its analog, 1-{6-[(2-[F-18] fluoroethyl) (methyl) amino] naphthalen-2-yl} ethanone ([F-18] FENE), to synthetic fibrils of A beta (1-40). FDDNP and FENE both appeared to bind to two kinetically distinguishable binding sites on A beta (1-40) fibrils. Fluorescence titrations yielded apparent K-d values of 0.12 and 0.16 nM for high-affinity binding sites for FDDNP and FENE, respectively, and apparent K-d values of 1.86 and 71.2 nM for the low-affinity binding sites. The traditional radioactive binding assays also produced apparent K-d values in the low nanomolar range. The presence of two kinetically distinguishable binding sites for FDDNP and FENE suggests multiple binding sites for SPs and identifies the parameters that allow for the structural optimization of this family of probes for in vivo use. The high-affinity binding of the probes to multiple binding sites on fibrils are consistent with results obtained with digital autoradiography, immunohistochemistry, and confocal fluorescence microscopy using human brain specimens of AD patients.