Potentiating effect of the ATP-sensitive potassium channel blocker glibenclamide on complex I inhibitor neurotoxicity in vitro and in vivo
Potentiating effect of the ATP-sensitive potassium channel blocker glibenclamide on complex I inhibitor neurotoxicity in vitro and in vivo
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DOI：
10.1016/j.neuro.2006.04.004
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发表时间：
2006-09-01
期刊：
影响因子：
3.4
通讯作者：
Bloomquist, Jeffrey R.
中科院分区：
文献类型：
--
作者：
Kou, Jinghong;Klorig, David C.;Bloomquist, Jeffrey R.
以前的研究已经证明了帕金森病中线粒体功能的缺陷。我们测量了复合物I（鱼藤酮、MPP+和HPP+）、II（氨卓）、IV（氰化钠）和解偶联剂（地乐酚）的线粒体抑制剂从小鼠纹状体突触体释放预载多巴胺的能力。这些化合物是有效的多巴胺释放剂，其作用依赖于钙。纹状体还含有大量的K-ATP（+）通道，在ATP下降时起保护作用。使用C57 BL/6小鼠，在体内也观察到格列本脲对MPTP毒性的选择性增强作用。纹状体多巴胺转运蛋白（DAT）和酪氨酸羟化酶（TH）蛋白的Western印迹表明，30 mg/kg格列本脲单独给药后，两周的每日治疗没有影响DAT和TH的表达，但它显着增强了单剂量20 mg/kg的MPTR Amdro或地乐酚单独或与格列本脲联合使用时DAT和TH的减少，没有改变DAT和TH的表达。在体外进一步评价了多巴胺释放的可能机制和格列本脲的选择性。Rb-86外排实验显示格列本脲可抑制鱼藤酮诱导的K+外排，但对地诺塞诱导的K+外排无明显影响。对处理过的突触体中ATP滴度的分析不支持线粒体抑制和K-ATP（+）通道激活之间的相关性。然而，活性氧（ROS）的测定表明，复合物I抑制剂产生的大量ROS是K-ATP（+）通道激活和格列本脲增强的一个促成因素。总体而言，这些结果表明，共同暴露于线粒体复合物I抑制剂和格列本脲或K-ATP（+）通道功能的遗传缺陷可能会增加纹状体多巴胺能系统的神经毒性。(C)2006年爱思唯尔公司All rights reserved.
Previous studies have demonstrated a deficiency in mitochondrial function in Parkinson's disease. We measured the ability of mitochondrial inhibitors of complexes I (rotenone, MPP+, and HPP+), II (amdro), IV (Na cyanide), and an uncoupler (dinoseb) to release preloaded dopamine from murine striatal synaptosomes. These compounds were potent dopamine releasers, and the effect was calcium-dependent. The striatum also contains a significant density of K-ATP(+) channels, which play a protective role during ATP decline. Blockage of these channels with glibenclamide only potentiated the dopamine release by complex I inhibitors, and a selective potentiating effect of glibenclamide on the toxicity of MPTP was also observed, in vivo, using C57BL/6 mice. Western blots of striatal dopamine transporter (DAT) and tyrosine hydroxylase (TH) proteins demonstrated that 30 mg/kg of glibenclamide alone did not affect the expression of DAT and TH after two weeks of daily treatments, but it significantly enhanced the reduction of DAT and TH by a single dose of 20 mg/kg of MPTR Amdro or dinoseb alone, or in conjunction with glibenclamide did not alter the expression of DAT and TH. The possible mechanisms underlying dopamine release and the selectivity of glibenclamide were further evaluated, in vitro. Rb-86 efflux assay showed that glibenclamide inhibited rotenone-induced K+ efflux, but not dinoseb-induced K+ efflux. Analysis of ATP titers in treated synaptosomes did not support a correlation between mitochondrial inhibition and K-ATP(+) channel activation. However, assay of reactive oxygen species (ROS) showed that greater amounts of ROS generated by complex I inhibitors was a contributory factor to K-ATP(+) channel activation and glibenclamide potentiation. Overall, these findings suggest that co-exposure to mitochondrial complex I inhibitors and glibenclamide or a genetic defect in K-ATP(+) channel function, may increase neurotoxicity in the striatal dopaminergic system. (C) 2006 Elsevier Inc. All rights reserved.