Staley J K, Talbot J Z, Ciliax B J, Miller G W, Levey A I, Kung M P, Kung H F, Mash D C
Department of Neurology, University of Miami School of Medicine, FL 33101, USA.
Brain Res. 1997 Feb 7;747(2):219-29. doi: 10.1016/s0006-8993(96)01196-1.
Radioligand binding to and immunolabeling of transport sites associated with monoamine-containing synaptic vesicles affords a novel approach for mapping the integrity of dopaminergic (DAergic) nerve terminals. The present study used [125I]iodovinyltetrabenazine ([125I]TBZ) and a fusion protein antibody directed at the large intraluminal loop of the neuronal vesicular monoamine transporter (hVMAT2-loop) as probes to assess the effects of chronic cocaine use on the integrity of DAergic nerve terminals in the striatum of cocaine fatalities. Visualization of [125I]TBZ binding in human brain revealed a distinct pattern of labeling throughout the rostral-caudal extent of the striatum. Saturation binding of [125I]TBZ in striatal membranes demonstrated a single high affinity site (Kd = 2.3 +/- 0.9 nM and Bmax = 55.5 +/- 8.1 pmol/g tissue) with a pharmacological profile (tetrabenazine > or = iodovinyltetrabenazine > ketanserin > or = reserpine > haloperidol > GBR 12909) consistent with the specific labeling of hVMAT2. Quantitative in vitro autoradiography demonstrated no significant alteration in the density of [125I]TBZ binding sites in the anterior and posterior sectors of the striatum in cocaine fatalities with and without preterminal excited delirium as compared to drug-free and age-matched control subjects. Similarly, the levels of hVMAT2-loop immunoreactivity were not significantly different across control and cocaine fatality groups. The results demonstrate the lack of an alteration in [125I]TBZ binding sites and hVMAT2 protein in the striatum from a young cohort of cocaine fatalities. Since striatal VMAT2 is primarily associated with DAergic nerve terminals, these results suggest that chronic cocaine use failed to affect the integrity of striatal DAergic nerve terminals.
放射性配体与含单胺突触小泡相关转运位点的结合及免疫标记为绘制多巴胺能（DA能）神经末梢的完整性提供了一种新方法。本研究使用[125I]碘乙烯基四苯嗪（[125I]TBZ）和针对神经元囊泡单胺转运体大腔内环的融合蛋白抗体（hVMAT2-loop）作为探针，评估长期使用可卡因对可卡因致死病例纹状体中DA能神经末梢完整性的影响。[125I]TBZ在人脑中的结合可视化显示，在纹状体的头-尾范围内有明显的标记模式。[125I]TBZ在纹状体膜中的饱和结合显示出一个单一的高亲和力位点（Kd = 2.3 +/- 0.9 nM，Bmax = 55.5 +/- 8.1 pmol/g组织），其药理学特征（四苯嗪≥碘乙烯基四苯嗪＞酮色林≥利血平＞氟哌啶醇＞GBR 12909）与hVMAT2的特异性标记一致。定量体外放射自显影显示，与无药物且年龄匹配的对照受试者相比，有和无前终末期激越性谵妄的可卡因致死病例纹状体前后区[125I]TBZ结合位点的密度没有显著变化。同样，hVMAT2-loop免疫反应性水平在对照和可卡因致死病例组之间没有显著差异。结果表明，年轻的可卡因致死病例队列的纹状体中[125I]TBZ结合位点和hVMAT2蛋白没有改变。由于纹状体VMAT2主要与DA能神经末梢相关，这些结果表明长期使用可卡因未能影响纹状体DA能神经末梢的完整性。
