Venditti P, Daniele C M, De Leo T, Di Meo S
Dipartimento di Fisiologia Generale ed Ambientale, Università di Napoli 'Federico II', Napoli, Italia.
Cell Physiol Biochem. 1998;8(6):328-38. doi: 10.1159/000016294.
This study was designed to investigate the possible oxidative changes associated with alterations in cytochrome P450 levels in rat liver. Accordingly, extent of peroxidative processes, cytochrome and antioxidant content, capacity to face an oxidative stress were determined in liver microsomes, mitochondria, and homogenates from normal and phenobarbital (PB)-treated rats. Liver content of microsomal and mitochondrial proteins was also determined by the values of the activities of marker enzymes (glucose-6-phosphatase and cytochrome oxidase, respectively) in liver homogenate and in two cellular fractions. The increase in the liver content of microsomal and mitochondrial proteins indicated that PB caused proliferation of both smooth endoplasmic reticulum and mitochondrial population. Treatment with PB also gave rise to a general increase in peroxidative reactions (evaluated measuring malondialdehyde and hydroperoxides (HPs)), in the different cell compartments, even though HPs were not found significantly increased in mitochondrial fraction. The increase in peroxidative processes was associated with significant decreases in antioxidant concentration (expressed in terms of equivalent concentration of an antioxidant, such as the desferrioxamine), in all preparations from PB-treated rats. The response to oxidative stress in vitro (evaluated determining the parameters characterizing light emission from preparations stressed with sodium perborate) showed a substantial PB-induced increase in the susceptibility to oxidative challenge only in liver homogenate. The lack of changes in the mitochondrial preparations is likely due to decrease in concentration of both free radical producing species and antioxidants. The lack of changes in microsomal fraction is apparently in contrast with its lower oxidant capacity and higher content of cytochromes which are able to determine sensitivity to pro-oxidants. However, it could be due to the ability of cytochrome P450 to interact with the active oxygen species formed at its active center.
本研究旨在调查与大鼠肝脏中细胞色素P450水平变化相关的可能的氧化改变。因此，测定了正常大鼠和经苯巴比妥（PB）处理的大鼠肝脏微粒体、线粒体和匀浆中过氧化过程的程度、细胞色素和抗氧化剂含量以及面对氧化应激的能力。还通过肝脏匀浆和两个细胞组分中标记酶（分别为葡萄糖-6-磷酸酶和细胞色素氧化酶）的活性值来测定微粒体和线粒体蛋白质的肝脏含量。微粒体和线粒体蛋白质肝脏含量的增加表明PB导致了滑面内质网和线粒体数量的增殖。PB处理还导致不同细胞区室中过氧化反应普遍增加（通过测量丙二醛和氢过氧化物（HPs）来评估），尽管线粒体组分中的HPs未发现显著增加。在所有来自PB处理大鼠的制剂中，过氧化过程的增加与抗氧化剂浓度的显著降低（以抗氧化剂如去铁胺的等效浓度表示）相关。体外对氧化应激的反应（通过测定用过硼酸钠应激的制剂的发光特征参数来评估）表明，仅在肝脏匀浆中，PB诱导对氧化挑战的敏感性大幅增加。线粒体制剂缺乏变化可能是由于自由基产生物质和抗氧化剂浓度均降低。微粒体组分缺乏变化显然与其较低的氧化能力和较高的细胞色素含量形成对比，而细胞色素能够决定对促氧化剂的敏感性。然而，这可能是由于细胞色素P450与在其活性中心形成的活性氧物种相互作用的能力。
