Comparison of [123I]beta-CIT and [123I]IPCIT as single-photon emission tomography radiotracers for the dopamine transporter in nonhuman primates.
Comparison of [123I]beta-CIT and [123I]IPCIT as single-photon emission tomography radiotracers for the dopamine transporter in nonhuman primates.
复制标题
[123I]beta-CIT 和 [123I]IPCIT 作为非人类灵长类动物多巴胺转运蛋白的单光子发射断层扫描放射性示踪剂的比较。
DOI：
10.1007/bf00997241
复制
发表时间：
1995
期刊：
影响因子：
--
通讯作者：
Wang,S
中科院分区：
文献类型：
--
作者：
Scanley,BE;al-Tikriti,MS;Gandelman,MS;Laruelle,M;Zea-Ponce,Y;Baldwin,RM;Zoghbi,SS;Hoffer,PB;Charney,DS;Wang,S
Single-photon emission tomographic (SPET) imaging with the radiotracer [123I]2β-carbomethoxy-3β-(4-iodophenyl)tropane ([123I]β-CIT) has been reported to be a useful in vivo measure of dopamine (DA) transporters. However, in addition to its high DA transporter affinity,β-CIT also binds with high affinity to serotonin (5-HT) transporters. 2β-Carboisopropoxy-3β-(4-iodophenyl)tropane (IPCIT) has been demonstrated by in vitro studies to have higher selectivity for the DA transporter. We compared [123I]β-CIT and [123I]IPCIT SPET imaging and plasma metabolite analyses in baboons to evaluate the potential advantages of [123I]IPCIT for quantitative in vivo measurements of DA transporter densities. Both tracers had low levels (2% of total plasma123I activity) of lipophilic radiolabeled metabolites at 420 min. [123I]IPCIT had significantly higher binding to plasma proteins. The average percent free (nonprotein bound) [123I]β-CIT and [123I]IPCIT were 52%±7% and 14%±6%, respectively. Region of interest uptake data were normalized by injected dose and body weight. Consistent with the high density of 5-HT transporters in the midbrain and the lower 5-HT transporter affinity of IPCIT, the normalized peak specific midbrain uptake of [123I]β-CIT (1.7±0.5) was higher than that of [123I]IPCIT (0.4±0.2). Consistent with its greater lipophilicity, [123I]IPCIT had higher nonspecific uptake, such that normalized cerebellar uptake of [123I]IPCIT was about twice that of [123I]β-CIT. The ratio of specific to nonspecific uptake in striatum was greater for [123I]β-CIT compared to [123I]IPCIT; however, striatal binding potentials and distribution volumes were not significantly different. In conclusion, [123I]IPCIT demonstrated in vivo a higher DA transporter selectivity and higher level of nonspecific uptake.
