Sawicka Ewa, Długosz Anna
Department of Toxicology, Wrocław Medical University, Wrocław, Poland.
Int J Occup Med Environ Health. 2008;21(3):201-9. doi: 10.2478/v10001-008-0022-z.
Previous research on a group of workers occupationally exposed to styrene, ethylene glycol, toluene, p-xylene and their mixture showed elevated levels of the main products of lipid peroxidation: malondialdehyde and 4-hydroxynonenal (MDA+,4-HNE) in plasma [1]. Moreover, an earlier in vitro study indicated a synergistic interaction between styrene and ethylene glycol on lipid peroxidation [2]. Therefore, it seemed interesting to investigate the effect of combined exposure to toluene and p-xylene on lipid peroxidation and define the type of the interaction.
An in vitro model of human placenta mitochondria was used in the study. The concentration of TBARS (thiobarbituric active reagent species) was measured by spectrophotometry, and of hydroxyl radical (.OH) by assessment of deoxyribose degradation. It was investigated whether the administration of coenzyme Q10 (CoQ10) could have a protective function (if given before solvent exposure) or a reparatory function (if given after exposure) in solvent-induced oxidative stress.
Exposure to p-xylene at concentrations ranging from 5.3 to 265 microg/ml produced an increase in TBARS concentration. The results showed that p-xylene had a stronger influence on lipid peroxidation than toluene. The mixture of toluene and p-xylene induced an antagonistic effect on lipid peroxidation, measured as TBARS concentration. The mechanism connected with .OH generation was found to play an important role in the oxidative damage to lipids resulting from p-xylene exposure. Administration of coenzyme Q10 at the doses of 3.0 and 12.0 microg/ml successfully decreased the TBARS level that was elevated after solvent exposure.
In contrast to the synergistic effect that the mixture of styrene and ethylene glycol had on lipid peroxidation (previous study), an antagonism between toluene and p-xylene could be observed. The coenzyme Q10 can be considered a protective agent against lipid peroxidation.
先前针对一组职业性接触苯乙烯、乙二醇、甲苯、对二甲苯及其混合物的工人开展的研究显示，血浆中脂质过氧化的主要产物丙二醛和4-羟基壬烯醛（MDA+，4-HNE）水平升高[1]。此外，一项早期体外研究表明，苯乙烯与乙二醇在脂质过氧化方面存在协同相互作用[2]。因此，研究甲苯和对二甲苯联合暴露对脂质过氧化的影响并确定相互作用类型似乎很有意思。
本研究采用人胎盘线粒体的体外模型。通过分光光度法测量硫代巴比妥酸活性反应物（TBARS）的浓度，通过评估脱氧核糖降解来测量羟基自由基（·OH）的浓度。研究了辅酶Q10（CoQ10）给药（若在溶剂暴露前给药则具有保护作用，若在暴露后给药则具有修复作用）是否对溶剂诱导的氧化应激具有保护或修复功能。
暴露于浓度范围为5.3至265微克/毫升的对二甲苯会导致TBARS浓度升高。结果表明，对二甲苯对脂质过氧化的影响比对甲苯更强。甲苯和对二甲苯的混合物对脂质过氧化产生拮抗作用，以TBARS浓度衡量。发现与·OH生成相关的机制在对二甲苯暴露导致的脂质氧化损伤中起重要作用。以3.0和12.0微克/毫升的剂量给予辅酶Q10成功降低了溶剂暴露后升高的TBARS水平。
与苯乙烯和乙二醇混合物对脂质过氧化的协同作用（先前研究）相反，可以观察到甲苯和对二甲苯之间存在拮抗作用。辅酶Q10可被视为一种抗脂质过氧化的保护剂。
