Staats D A, Lohr D P, Colby H D
Department of Biomedical Sciences, University of Illinois College of Medicine, Rockford 61107.
Mol Cell Endocrinol. 1989 Apr;62(2):189-95. doi: 10.1016/0303-7207(89)90005-1.
Prior studies demonstrated far greater amounts of lipid peroxidation (LP) in mitochondria from the zona reticularis (inner zone) of the guinea pig adrenal cortex than in mitochondria from the outer zone (zona fasciculata + zona glomerulosa) of the gland. alpha-Tocopherol concentrations, by contrast, were greater in the outer zone. To determine if the differences in alpha-tocopherol content were responsible for the regional differences in LP, the effects of alpha-tocopherol deficiency on mitochondrial LP were investigated. Tocopherol deficiency had relatively little effect on ferrous ion- or ascorbic acid-induced LP in inner zone mitochondria. However, depletion of adrenal tocopherol substantially increased outer zone LP, eliminating the differences between the two zones. Fatty acid analyses revealed that mitochondria from tocopherol-deficient animals contained significantly less linoleic acid (C18:2) and arachidonic acid (C20:4) than those from controls, suggesting peroxidative losses in vivo. In mitochondria from control animals, subphysiological concentrations of ascorbic acid stimulated LP, but physiological levels did not. However, in tocopherol-depleted mitochondria, even physiological concentrations of ascorbic acid stimulated LP. The results indicate that the intra-adrenal distribution of alpha-tocopherol is responsible for the regional differences in mitochondrial LP and that alpha-tocopherol is a major determinant of ascorbic acid actions on adrenal LP. The data also provide evidence of adrenal LP in vivo in tocopherol-deficient animals.
先前的研究表明，豚鼠肾上腺皮质网状带（内层）线粒体中的脂质过氧化（LP）量远高于该腺体外层（束状带+球状带）线粒体中的脂质过氧化量。相比之下，外层的α-生育酚浓度更高。为了确定α-生育酚含量的差异是否是LP区域差异的原因，研究了α-生育酚缺乏对线粒体LP的影响。生育酚缺乏对网状带线粒体中由亚铁离子或抗坏血酸诱导的LP影响相对较小。然而，肾上腺生育酚的消耗显著增加了外层的LP，消除了两个区域之间的差异。脂肪酸分析显示，来自缺乏生育酚动物的线粒体中亚油酸（C18:2）和花生四烯酸（C20:4）的含量明显低于对照组动物的线粒体，这表明体内存在过氧化损失。在对照动物的线粒体中，亚生理浓度的抗坏血酸会刺激LP，但生理水平的抗坏血酸不会。然而，在缺乏生育酚的线粒体中，即使是生理浓度的抗坏血酸也会刺激LP。结果表明，肾上腺内α-生育酚的分布是线粒体LP区域差异的原因，并且α-生育酚是抗坏血酸对肾上腺LP作用的主要决定因素。这些数据还提供了维生素E缺乏动物体内肾上腺LP的证据。
