Larisch R, Schommartz B, Vosberg H, Müller-Gärtner H W
Department of Nuclear Medicine, Heinrich-Heine-University, Moorenstrasse 5, Düsseldorf, 40225, Germany.
Neuroimage. 1999 Sep;10(3 Pt 1):261-8. doi: 10.1006/nimg.1999.0461.
Pharmacologically induced dopamine release can influence the postsynaptic receptor binding of dopaminergic radioligands. This effect has recently been described using in vivo imaging methods and has been attributed to competition of radiotracers with the endogenous ligand. The present study examines the effect of a motor activation task on dopamine release and the consequences of this release on the binding of the selective D(2) receptor ligand (123)I-iodobenzamide (IBZM) to striatal dopamine D(2) receptors. Eight subjects were asked to write a text beginning immediately before IBZM injection and continuing for 30 min thereafter. Eighteen other subjects remained in a supine resting state during this period and served as a control group. All subjects were right handed. We hypothesized that the writing task would lead to an increase of dopamine release. The increased competition of the endogenous ligand with IBZM should lead to a decreased postsynaptic IBZM binding in the experimental group. Images were acquired and reconstructed identically and anatomically normalized to a computerized brain atlas. Regions of interest were drawn covering the striatum and three different reference regions. Ratios of striatal-to-reference-tissue radioactivity accumulation were calculated as semi-quantitative estimates of D(2) receptor binding potential. This decreased bilaterally, although right-sided significantly more than left, regardless of the choice of reference region. These data show that writing with the right hand compared to a supine resting state leads to a decrease of striatal IBZM accumulation. According to our primary hypothesis this reflects dopamine release.
药理学诱导的多巴胺释放可影响多巴胺能放射性配体的突触后受体结合。最近已使用体内成像方法描述了这种效应，并将其归因于放射性示踪剂与内源性配体的竞争。本研究考察了运动激活任务对多巴胺释放的影响，以及这种释放对选择性D(2)受体配体（123）I-碘苯甲酰胺（IBZM）与纹状体多巴胺D(2)受体结合的影响。8名受试者被要求在注射IBZM前立即开始写一篇文章，并持续30分钟。在此期间，另外18名受试者保持仰卧休息状态，作为对照组。所有受试者均为右利手。我们假设写作任务会导致多巴胺释放增加。内源性配体与IBZM竞争的增加应导致实验组突触后IBZM结合减少。图像以相同方式采集和重建，并在解剖学上归一化到计算机脑图谱。绘制覆盖纹状体和三个不同参考区域的感兴趣区域。计算纹状体与参考组织放射性积累的比率，作为D(2)受体结合潜能的半定量估计。无论参考区域如何选择，这种结合双侧均减少，尽管右侧比左侧减少得更明显。这些数据表明，与仰卧休息状态相比，右手写作会导致纹状体IBZM积累减少。根据我们的主要假设，这反映了多巴胺释放。
