Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del IPN, Zacatenco, Ciudad de México, México.
Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del IPN, Zacatenco, Ciudad de México, México.
Pharmacol Rep. 2018 Feb;70(1):146-155. doi: 10.1016/j.pharep.2017.08.007. Epub 2017 Aug 30.
Clobenpropit, a potent antagonist/inverse agonist at the histamine H receptor (HR), reduced the cytotoxic action of 6-hydroxydopamine (6-OHDA) in neuroblastoma SH-SY5Y cells transfected with the human HR. We therefore set out to study whether this effect involved a receptor-independent action on dopamine transport.
The uptake of [H]-dopamine was assayed in SH-SY5Y cells and rat striatal or cerebro-cortical isolated nerve terminals (synaptosomes). Clobenpropit binding to the human norepinephrine (NET) and dopamine (DAT) transporters was analyzed by molecular modeling.
In SH-SY5Y cells, [H]-dopamine uptake was inhibited by desipramine (selective NET inhibitor), GBR-12909 (selective DAT inhibitor), and fluoxetine (selective inhibitor of the serotonin transporter, SERT) with IC values 37, 537, and 2800nM, respectively. The potency rank order indicates that [H]-dopamine uptake is primarily performed by NET. Clobenpropit inhibited [H]-dopamine uptake (maximum inhibition 82.7±2.8%, IC 490nM), and the effect was reproduced by the HR antagonist/inverse agonist iodophenpropit, but not by the agonists R-α-methylhistamine and immepip or the antagonists/inverse agonists ciproxifan and A-331440. Clobenpropit also inhibited [H]-dopamine uptake by rat striatal and cerebro-cortical synaptosomes (-54.6±11.3% and -46.3±9.6%, respectively, at 10μM). Modeling of the human NET and DAT obtained by homology from the crystal of Drosophila melanogaster DAT showed that clobenpropit can bind to a site also recognized in both transporters by nisoxetine, a potent NET inhibitor.
These data indicate a direct inhibitory effect of clobenpropit on catecholamine transport.
氯苯丙哌嗪（一种组胺 H 受体（HR）的有效拮抗剂/反向激动剂）可减少转染人 HR 的神经母细胞瘤 SH-SY5Y 细胞中 6-羟多巴胺（6-OHDA）的细胞毒性作用。因此，我们着手研究这种效应是否涉及多巴胺转运的受体非依赖性作用。
通过分子建模分析氯苯丙哌嗪与人类去甲肾上腺素（NET）和多巴胺（DAT）转运体的结合。在 SH-SY5Y 细胞和大鼠纹状体或脑皮质分离的神经末梢（突触体）中测定 [H]-多巴胺的摄取。
在 SH-SY5Y 细胞中，[H]-多巴胺摄取被去甲丙咪嗪（选择性 NET 抑制剂）、GBR-12909（选择性 DAT 抑制剂）和氟西汀（选择性 5-羟色胺转运体抑制剂，SERT）抑制，IC 值分别为 37、537 和 2800 nM。效力等级顺序表明 [H]-多巴胺摄取主要由 NET 完成。氯苯丙哌嗪抑制 [H]-多巴胺摄取（最大抑制 82.7±2.8%，IC 490nM），该作用可被 HR 拮抗剂/反向激动剂碘苯丙哌嗪重现，但不能被激动剂 R-α-甲基组氨酸和 immepip 或拮抗剂/反向激动剂 ciproxifan 和 A-331440 重现。氯苯丙哌嗪还抑制大鼠纹状体和脑皮质突触体中的 [H]-多巴胺摄取（在 10μM 时分别为-54.6±11.3%和-46.3±9.6%）。通过同源性从黑腹果蝇 DAT 的晶体获得的人 NET 和 DAT 的建模表明，氯苯丙哌嗪可以与尼索西汀（一种有效的 NET 抑制剂）在两种转运体中识别的结合位点结合。
这些数据表明氯苯丙哌嗪对儿茶酚胺转运具有直接抑制作用。
