Limitations of cyclosporin A inhibition of the permeability transition in CNS mitochondria
Limitations of cyclosporin A inhibition of the permeability transition in CNS mitochondria
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DOI：
10.1523/jneurosci.20-22-08229.2000
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发表时间：
2000-11-15
影响因子：
5.3
通讯作者：
Dubinsky, JM
中科院分区：
文献类型：
--
作者：
Brustovetsky, N;Dubinsky, JM
线粒体渗透性转变的激活可能导致兴奋性毒性神经元死亡（Ankarcrona等人，1996年; Dubinsky和Levi，1998年）。然而，环孢菌素A（CsA），一个有效的抑制剂的渗透性转换在肝线粒体，只保护对神经元损伤的有限剂量的谷氨酸和选定的缺血范例。使用分离的脑线粒体分析了缺乏一致的CsA抑制线粒体通透性转换。通过监测线粒体膜电位（Δ psi），使用四苯基磷的分布，并通过监测线粒体肿胀，使用吸光度测量，评价线粒体内膜的渗透性的变化。代谢障碍，大的Ca 2+负荷，省略外部Mg 2+，或低剂量的棕榈酸或质子载体FCCP加剧Ca 2+诱导的持续去极化和肿胀，并消除CsA抑制。BSA恢复CsA抑制线粒体挑战与50 μ M的Ca 2+，但不是与100 μ M的Ca 2+。CsA不能阻止Ca ~（2+）诱导的线粒体去极化或在线粒体过度去极化时恢复线粒体。同样，CsA未能防止线粒体肿胀或PEG诱导的收缩后肿胀时，Ca 2+的挑战产生了强烈的，持续的去极化。因此，在脑线粒体CsA可能是有效的，仅作为一种抑制剂的渗透性转换和Ca 2+激活的低渗透性状态下的条件下的部分去极化。相比之下，ADP加寡霉素在所有测试条件下均抑制两种渗透性。在原位，CsA的神经保护作用可能仅限于谷氨酸的挑战足够毒性，以诱导渗透性转换，但没有那么严重，线粒体去极化超过阈值。
Activation of the mitochondrial permeability transition may contribute to excitotoxic neuronal death (Ankarcrona et al., 1996; Dubinsky and Levi, 1998). However, cyclosporin A (CsA), a potent inhibitor of the permeability transition in liver mitochondria, only protects against neuronal injury by limited doses of glutamate and selected ischemic paradigms. The lack of consistent CsA inhibition of the mitochondrial permeability transition was analyzed with the use of isolated brain mitochondria. Changes in the permeability of the inner mitochondrial membrane were evaluated by monitoring mitochondrial membrane potential (Delta psi), using the distribution of tetraphenylphosphonium, and by monitoring mitochondrial swelling, using light absorbance measurements. Metabolic impairments, large Ca2+ loads, omission of external Mg2+, or low doses of palmitic acid or the protonophore FCCP exacerbated Ca2+-induced sustained depolarizations and swelling and eliminated CsA inhibition. BSA restored CsA inhibition in mitochondria challenged with 50 muM Ca2+, but not with 100 muM Ca2+. CsA failed to prevent Ca2+-induced depolarization or to repolarize mitochondria when mitochondria were depolarized excessively. Similarly, CsA failed to prevent mitochondrial swelling or PEG-induced shrinkage after swelling when the Ca2+ challenge produced a strong, sustained depolarization. Thus in brain mitochondria CsA may be effective only as an inhibitor of the permeability transition and the Ca2+-activated low permeability state under conditions of partial depolarization. In contrast, ADP plus oligomycin inhibited both permeabilities under all of the conditions that were tested. In situ, the neuroprotective action of CsA may be limited to glutamate challenges sufficiently toxic to induce the permeability transition but not so severe that mitochondrial depolarization exceeds threshold.