Staats D A, Colby H D
Department of Biomedical Sciences, University of Illinois College of Medicine, Rockford, IL 61107.
J Steroid Biochem. 1987 Dec;28(6):637-42. doi: 10.1016/0022-4731(87)90391-8.
Lipid peroxidation (LP) and antioxidant levels were studied in the chromatically distinct inner (zona reticularis) and outer (zona fasciculata + zona glomerulosa) zones of the guinea pig adrenal cortex. Ferrous ion (Fe2+) produced a concentration-dependent (10(-5) to 10(-3) M) stimulation of microsomal LP in both zones, but LP, as estimated by malonaldehyde production, was far greater in the inner zone. Although cytosolic ascorbic acid content was similar in the two zones, microsomal tocopherol levels were approx 4 times greater in the outer than inner zone. Subphysiological concentrations of ascorbic acid, like Fe2+, initiated LP to a greater extent in inner than outer zone microsomes; optimal stimulation of LP by ascorbic acid occurred at concentrations of 100-200 microM in both zones. Physiological concentrations of ascorbic acid (1-5 mM), by contrast, did not initiate LP and, in fact, markedly inhibited Fe2+-induced LP in both inner and outer zone microsomal preparations. Outer zone microsomes were more sensitive to the antioxidant effects of ascorbic acid than were inner zone preparations. Addition of alpha-tocopherol to inner zone microsomal suspensions inhibited Fe2+-induced LP. The results indicate that there are regional differences in adrenocortical LP which may be caused by differences in tocopherol content. alpha-Tocopherol may serve important antioxidant functions within the adrenal cortex, thereby contributing to the functional zonation of the gland.
在豚鼠肾上腺皮质颜色不同的内层（网状带）和外层（束状带+球状带）区域研究了脂质过氧化（LP）和抗氧化剂水平。亚铁离子（Fe2+）在两个区域均产生浓度依赖性（10^(-5)至10^(-3)M）的微粒体LP刺激，但通过丙二醛生成估计的LP在内层区域要高得多。尽管两个区域的胞质抗坏血酸含量相似，但外层微粒体中的生育酚水平比内层区域大约高4倍。亚生理浓度的抗坏血酸与Fe2+一样，在内层微粒体中比外层微粒体更能引发LP；抗坏血酸对LP的最佳刺激在两个区域均发生在100-200 microM的浓度下。相比之下，生理浓度的抗坏血酸（1-5 mM）不会引发LP，实际上，在内外层微粒体制剂中均显著抑制Fe2+诱导的LP。外层微粒体比内层制剂对抗坏血酸的抗氧化作用更敏感。向内层微粒体悬浮液中添加α-生育酚可抑制Fe2+诱导的LP。结果表明，肾上腺皮质LP存在区域差异，这可能是由于生育酚含量的差异所致。α-生育酚可能在肾上腺皮质内发挥重要的抗氧化功能，从而有助于该腺体的功能分区。
