Cyclosporin a increases mitochondrial calcium uptake capacity in cortical astrocytes but not cerebellar granule neurons
Cyclosporin a increases mitochondrial calcium uptake capacity in cortical astrocytes but not cerebellar granule neurons
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DOI：
10.1007/s10863-006-9004-7
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发表时间：
2006-02-01
影响因子：
3
通讯作者：
Fiskum, Gary
中科院分区：
文献类型：
--
作者：
Bambrick, Linda L.;Chandrasekaran, Krish;Fiskum, Gary
分离的脑线粒体是来自不同细胞类型的异质混合物，并且这些子集可能对Ca 2+诱导的膜通透性转换（MPT）和环孢菌素A（CsA）对MPT的抑制具有不同的敏感性。本研究验证了这一假设，即星形胶质细胞和神经元的原代培养物内的线粒体表现出不同的能量依赖性Ca 2+摄取能力和不同程度的CsA增加其摄取能力。将星形胶质细胞和神经元悬浮在含有呼吸底物、ATP和Mg 2+的胞质样培养基中，在毛地黄皂苷的存在下选择性地透化质膜。通过培养基[Ca 2 +]的钙绿色5 N荧光监测来测量细胞内线粒体对添加的Ca 2+的摄取。透性星形胶质细胞有四倍高的Ca 2+摄取能力，相对于神经元和两倍高的含量的基础上的相对含量的线粒体的线粒体DNA和细胞色素氧化酶亚基1蛋白的测量评估。在星形胶质细胞中，2-5 μ M CsA预孵育可使Ca ~（2+）摄取能力增加两倍，而在神经元中CsA则无影响。使用添加的Ca 2+对线粒体膜电位的影响的测量获得了类似的结果。FK 506是一种与CsA相似但无MPT抑制活性的药物，对两种细胞类型均无影响。这些结果与星形胶质细胞中钙诱导的MPT的存在是一致的，即使在ATP的存在下，并且表明小脑颗粒神经元中的MPT对CsA抑制具有抗性。因此，CsA在体内的一些保护作用可能是通过保存星形胶质细胞内的线粒体功能完整性来介导的。
Isolated brain mitochondria are a heterogeneous mixture from different cell types and these subsets may have differing sensitivities to Ca2+-induced membrane permeability transition (MPT) and to inhibition of the MPT by cyclosporin A (CsA). This study tested the hypothesis that mitochondria within primary cultures of astrocytes and neurons exhibit different energy-dependent Ca2+ uptake capacities and different degrees to which CsA increases their uptake capacity. Astrocytes and neurons were suspended in a cytosol-like medium containing respiratory substrates, ATP, and Mg2+ in the presence of digitonin to selectively permeabilize the plasma membrane. Uptake of added Ca2+ by mitochondria within the cells was measured by Calcium Green 5N fluorescent monitoring of the medium [Ca2+]. Permeabilized astrocytes had a fourfold higher Ca2+ uptake capacity, relative to neurons and a twofold higher content based on relative contents of mitochondria assessed by measurements of mitochondrial DNA and cytochrome oxidase subunit 1 protein. In astrocytes the Ca2+ uptake capacity was increased twofold by preincubation with 2-5 mu M CsA, while in neurons CsA had no effect. Similar results were obtained using measurements of the effects of added Ca2+ on mitochondrial membrane potential. FK506, a drug similar to CsA but without MPT inhibitory activity, had no effect on either cell type. These results are consistent with the presence of a calcium-induced MPT in astrocytes, even in the presence of ATP, and indicate that the MPT in cerebellar granule neurons is resistant to CsA inhibition. Some of the protective effects of CsA in vivo may therefore be mediated by preservation of mitochondrial functional integrity within astrocytes.