Inhibitory Effects of Ascorbic Acid on the Binding of [3H]Dopamine Antagonists to Neostriatal Membrane Preparations : Relationship to Lipid Peroxidation
Inhibitory Effects of Ascorbic Acid on the Binding of [3H]Dopamine Antagonists to Neostriatal Membrane Preparations : Relationship to Lipid Peroxidation
复制标题
抗坏血酸对[3H]多巴胺拮抗剂与新纹状体膜制剂结合的抑制作用：与脂质过氧化的关系
作者：
R. Heikkila;F. Cabbat;L. Manzino
摘要：抗坏血酸、抗坏血酸钠和异抗坏血酸（抗坏血酸的立体异构体）抑制[3 H]螺哌啶与新纹状体膜制剂的立体特异性结合。在三种抗坏血酸类似物的中间浓度下获得更大的抑制作用（即，0.06和0.6mM）比在更高（6 mM）或更低（0.006mM）的浓度下更高。在平行实验中，三种抗坏血酸类似物诱导脂质过氧化，这也是更大的两个中间比在更高或更低的浓度。几种已知的脂质过氧化抑制剂，包括没食子酸丙酯、丁基化羟基茴香醚、丁基化羟基甲苯、α-萘酚和氯化钴，以及铁螯合剂EDTA和二亚乙基三胺五乙酸（diethylenetriaminepentaacetic acid），能够抵消抗坏血酸类似物对脂质过氧化和[3 H]螺哌啶结合的影响。这些数据强烈表明，铁催化的脂质过氧化是观察到的结合抑制作用的原因。在其他实验中，用抗坏血酸（0.6 mM）预孵育并随后洗涤的新纹状体膜制剂结合[3 H]螺哌啶的能力仍然大大降低，表明在结合试验期间不需要物理存在抗坏血酸以影响结合。这个实验程序似乎也是一种方法，其中[3 H]螺哌啶结合位点可以被灭活和清洗的灭活剂。
Abstract: Ascorbic acid, sodium ascorbate, and isoascorbic acid (the stereo‐isomer of ascorbic acid) inhibited the stereospecific binding of [3H]spiroperidol to neostriatal membrane preparations. Greater inhibitory effects were obtained at intermediate concentrations of the three ascorbic acid analogs (i.e., 0.06 and 0.6 mM) than at higher (6 mM) or lower (0.006 mM) concentrations. In parallel experiments, the three ascorbic acid analogs induced lipid peroxidation, which was also greater at the two intermediate than at higher or lower concentrations. Several known inhibitors of lipid peroxidation, including propyl gallate, butylated hydroxyanisole, butylated hydroxytoluene, α‐naphthol, and cobalt chloride, as well as the iron chelating agents EDTA and DETAPAC (diethylenetriaminepentaacetic acid) were able to counteract the effects of the ascorbic acid analogs on both lipid peroxidation and on [3H]spiroperidol binding. These data strongly suggest that an iron‐catalyzed lipid peroxidation is responsible for the observed inhibitory effects on binding. In other experiments, neostriatal membrane preparations that were preincubated with ascorbic acid (0.6 mM) and subsequently washed still had greatly diminished capacity to bind [3H]spiroperidol, indicating that ascorbic acid need not be physically present during the binding assay in order to affect binding. This experimental procedure also appears to be a way in which [3H]spiroperidol binding sites can be inactivated and washed free of the inactivating agent.