Fujita M, Takatoku K, Matoba Y, Nishiura M, Kobayashi K, Inoue O, Nishimura T
Division of Tracer Kinetics, Biomedical Research Center, Osaka University Medical School, Osaka 565, Japan.
Eur J Nucl Med. 1996 Apr;23(4):431-6. doi: 10.1007/BF01247372.
Iodine-123-labelled 3beta-(4-iodophenyl)tropane-2beta-carboxylic acid ([123I]beta-CIT) labels both the dopamine transporter (DAT) and the serotonin transporter (5-HTT) and this ligand is able to clarify pathological changes in both dopaminergic and serotonergic systems. However, the differential kinetics of beta-CIT binding to DAT and 5-HTT has not been clarified fully. In this study we examined time-activity curves of [123I]beta-CIT in individual regions in the rat brain. Using cerebellum as the reference region, k3 and k4 values were estimated by a two-compartment kinetic analysis. In the striatum, the kinetics was slowest among all brain areas. In this area specific binding reached its peak 4 h after the injection. In the hypothalamus, specific binding reached its peak 1 h after the injection and its amount did not change until 4 h after the injection. In the occipital cortex, the binding and washout of the ligand were fastest among all brain regions. Estimated k3 values were 0.040+/-0.003 in the striatum, 0.019+/-0.002 in the hypothalamus and 0.082+/-0.011 in the occipital cortex (min-1, mean +/-SD). Estimated k4 values were 0.0034+/-0.0005 in the striatum, 0.0071+/-0.0009 in the hypothalamus and 0.083+/-0.013 in the occipital cortex (min-1, mean +/-SD). Therefore binding kinetics of [123i]beta-cit in the region rich in dat is apparently different from that in the region rich in 5-HTT. These results will provide fundamental data to image both DAT and 5-HTT in one series of examinations with [123I]beta-CIT.
碘-123标记的3β-(4-碘苯基)托烷-2β-羧酸([123I]β-CIT)可标记多巴胺转运体(DAT)和5-羟色胺转运体(5-HTT)，该配体能够明确多巴胺能和5-羟色胺能系统的病理变化。然而，β-CIT与DAT和5-HTT结合的差异动力学尚未完全阐明。在本研究中，我们检测了大鼠脑内各区域[123I]β-CIT的时间-活性曲线。以小脑作为参考区域，通过二室动力学分析估算k3和k4值。在纹状体中，动力学在所有脑区中最慢。在该区域，特异性结合在注射后4小时达到峰值。在下丘脑中，特异性结合在注射后1小时达到峰值，并且其含量在注射后4小时内没有变化。在枕叶皮质中，配体的结合和洗脱在所有脑区中最快。纹状体中估算的k3值为0.040±0.003，下丘脑中为0.019±0.002，枕叶皮质中为0.082±0.011（分钟-1，平均值±标准差）。纹状体中估算的k4值为0.0034±0.0005，下丘脑中为0.0071±0.0009，枕叶皮质中为0.083±0.013（分钟-1，平均值±标准差）。因此，[123I]β-CIT在富含DAT的区域的结合动力学明显不同于富含5-HTT的区域。这些结果将为用[123I]β-CIT在一系列检查中同时成像DAT和5-HTT提供基础数据。
