Radioligand binding and immunoautoradiographic evidence for a lack of toxicity to dopaminergic nerve terminals in human cocaine overdose victims
Radioligand binding and immunoautoradiographic evidence for a lack of toxicity to dopaminergic nerve terminals in human cocaine overdose victims
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DOI：
10.1016/s0006-8993(96)01196-1
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发表时间：
1997-02-07
期刊：
影响因子：
2.9
通讯作者：
Mash, DC
中科院分区：
文献类型：
--
作者：
Staley, JK;Talbot, JZ;Mash, DC
放射性配体与含有单胺的突触囊泡相关的转运位点的结合和免疫标记提供了一种用于映射多巴胺能（DA能）神经末梢完整性的新方法，本研究使用[（125）]碘乙烯基丁苯那嗪（[I-125]TBZ）和针对神经元囊泡单胺转运蛋白的大管腔内环的融合蛋白抗体（hVMAT 2-环）作为探针来评估慢性可卡因使用对可卡因致死者纹状体中DA能神经末梢完整性的影响。[I-125]TBZ在人脑中结合的可视化显示了整个纹状体吻尾侧范围内的独特标记模式。[I-125]TBZ在纹状体膜上的饱和结合显示了单一的高亲和力位点（Kd = 2.3 +/- 0.9 nM和B-max = 55.5 +/- 8.1 pmol/g组织），具有药理学特征（丁苯那嗪大于或等于碘乙烯丁苯那嗪>酮色林大于或等于利血平>氟哌啶醇> GBR 12909）与hVMAT 2的特异性标记一致。定量体外放射自显影显示，与无药物和年龄匹配的对照受试者相比，可卡因致死伴和不伴终末前兴奋性谵妄的纹状体前部和后部的[I-125]TBZ结合位点密度无显著变化。类似地，hVMAT 2环免疫反应性的水平在对照组和可卡因致死组之间没有显著差异。结果表明，缺乏改变[I-125]TBZ结合位点和hVMAT 2蛋白质在纹状体从一个年轻的队列可卡因死亡。由于纹状体VMAT 2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。
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 [(125)]iodovinyltetrabenazine ([I-125]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 [I-125]TBZ binding in human brain revealed a distinct pattern of labeling throughout the rostral-caudal extent of the striatum. Saturation binding of [I-125]TBZ in striatal membranes demonstrated a single high affinity site (K-d = 2.3 +/- 0.9 nM and B-max = 55.5 +/- 8.1 pmol/g tissue) with a pharmacological profile (tetrabenazine greater than or equal to iodovinyltetrabenazine > ketanserin greater than or equal to reserpine > haloperidol > GBR 12909) consistent with the specific labeling of hVMAT2. Quantitative in vitro autoradiography demonstrated no significant alteration in the density of [I-125]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 [I-125]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.