五味子酚对突触体膜脂质过氧化损伤保护作用的ESR研究

本文用自旋标记方法研究了经过脂质过氧化作用后脑突触体膜的生物物理特性的变化以及抗氧化剂五味子酚对膜的保护作用．用脂肪酸标记物５－ＤＯＸＹＬ和１６－ＤＯＸＹＬ标记研究了膜脂流动性，结果表明，受脂质过氧化损伤后膜脂流动性降低；用马来酰亚胺自旋标记研究了脂质过氧化对脑突触体膜蛋白上巯基的影响，结果发现，脂质过氧化后，ＥＳＲ波谱的弱强固定化比值Ｗ／Ｓ增大，总的效应表现为膜蛋白上巯基结合位点裸露程度变大。加入五味子酚后能抑制膜流动性的降低，且能使弱强固定化比值Ｗ／Ｓ趋向于未受脂质过氧化损伤的突触体膜的弱强固定化比值Ｗ／Ｓ，证明了五味子酚能降低脂质过氧化对膜的损伤程度，对膜起保护作用。

ESR STUDIES ON PROTECTION EFFECT OF SCHISANHENOL ON SYNAPTOSOMAL MEMBRANES FROM LIPID PEROXIDATION

Synaptosomes were prepared from rat cerebral cortex and labeled with lipid-specific spin probes 5-DOXYL and 16-DOXYL in synaptosomal membranes treated with Fe2+/Fe3+, became larger than those of controls, indicating that the fluidity of synaptosomal membranes was decreased. On the other hand, synaptosomes were covalently labeled with the proteinthiol-selective spin label 3-Maleimide-Proxyl. The ratio of the weakly immobilized component to the strongly immobilizedcomponent(W/S) and the rotational correlation time(τc) were calculated on the basis of ESR spectra. The W/S ratio of 3-Maleimide-Proxyl labeled synaptosomes, oxidatively stressed by contact with Fe2+ /Fe3+, was found to be larger than thatof controls, while τc became smaller than that of control, indicating that sulfbydryl binding sites on the membrane proteinswere exposed from inner membrane to outer membrane, and steric hindrance about 3-Maleimide-Proxyl binding sites was decreased. To observe the effects of Schisanhenol(Sal) on the physical state of membrane proteins and bilayer lipids of synaptosome, the synaptosomal membranes were incubated with Sal before the membranes were oxidized. It was found that theorder parameter(S) and the rotational correlation time(τc) of synaptosomal membranes treated with Sal were significantlylower than those of the membranes attacked by free radicals, indicating that synaptosomal membrane.fluidity was protectedby Sal from the change caused by free radical injury. We also found that the ratio of W/S of Sal-treated synaptosomal membranes became smaller than that of the membranes attacked by free radicals, indicating that Sal is capable of protecting snaptosomal membranes from damages induced by free radicals.