Basha P Siraj, Rani A Usha
Department of Zoology, Division of Environmental Biology, S.V. University, Tirupati, Chitoor District 517 502, Andhra Pradesh, India.
Ecotoxicol Environ Saf. 2003 Oct;56(2):218-21. doi: 10.1016/s0147-6513(03)00028-9.
Antioxidant defenses consisting of catalase, superoxide dismutase (SOD), xanthine oxidase (XOD), glutathione peroxidase (GPX), and glutathione S-transferase were estimated in liver and kidney of freshwater fish subjected to a sublethal concentration of cadmium chloride (Cd2+), i.e., 5 ppm. The aim of the study was to evaluate the role of antioxidant defenses during cadmium-induced oxidative stress. Significant elevations in liver and kidney of all of the above detoxification enzymes were evident from the 7th day onward, were maintained until the 15th day, and then decreased slightly on the 30th day of exposure to cadmium stress. Between the two tissues studied, liver recorded higher activity for all enzymes except GPX, which was elevated significantly in kidney (82.85%). Both liver and kidney recorded more or less similar increases of SOD (86.61% and 86.32%, respectively), and XOD (86.41% and 84.19%, respectively). The findings indicate that tissue glutathione-dependent enzymes as well as other antioxidant enzymes function in protection against Cd2+ toxicity and that these antioxidants provide a first line of defense against Cd2+ before the induction of any metallothionein synthesis occurs.
在经受氯化镉（Cd2+）亚致死浓度（即5 ppm）的淡水鱼的肝脏和肾脏中，对由过氧化氢酶、超氧化物歧化酶（SOD）、黄嘌呤氧化酶（XOD）、谷胱甘肽过氧化物酶（GPX）和谷胱甘肽S-转移酶组成的抗氧化防御系统进行了评估。该研究的目的是评估抗氧化防御系统在镉诱导的氧化应激中的作用。从第7天起，上述所有解毒酶在肝脏和肾脏中的活性均显著升高，并一直维持到第15天，然后在接触镉应激的第30天略有下降。在所研究的两个组织中，除GPX外，肝脏中所有酶的活性均较高，而GPX在肾脏中的活性显著升高（82.85%）。肝脏和肾脏中SOD（分别为86.61%和86.32%）和XOD（分别为86.41%和84.19%）的增加或多或少相似。研究结果表明，组织中的谷胱甘肽依赖性酶以及其他抗氧化酶在抵御Cd2+毒性方面发挥作用，并且在诱导任何金属硫蛋白合成之前，这些抗氧化剂为抵御Cd2+提供了第一道防线。
