Background

Metals can disturb the integrity of physiological and biochemical mechanisms in fish. Thus components of defense as an antioxidant system are significant biomarkers due to their vital role in coping with metal stress. The aim of the current study is to investigate the direct effects of Cd, Cu, and Zn sublethal exposures (in vitro) on the antioxidant system parameters in the liver and kidney of Nile tilapia.

Methods

The antioxidant enzyme activities and GSH levels were analyzed after in vitro sublethal metal (200 and 400 μg/L Cd, Cu, and Zn) treatments of Oreochromis niloticus liver and kidney supernatants.

Results

Metals even at lower levels caused significant changes in the levels of antioxidant system parameters due to concentration, metal, and tissue type. GSH metabolism parameters were more responsive to the metal effect. TBARS levels and GPX activity were mostly increased while CAT, SOD, rGSH, and GSH/GSSG levels decreased. The kidney was more affected than the liver in vitro conditions. Cu was more effective in the liver whereas it was Zn for the kidney. Cd caused negative correlations among the antioxidant enzymes. Significant correlations were found between enzymes and GSH levels upon Zn and Cu exposures.

Conclusions

Direct metal effects may trigger different response trends due to their nature and tissue differences. The current data provide a knowledge about which antioxidant biomarkers can define better the oxidative stress caused by direct metal effect for further studies including in vivo experiments.

中文翻译：

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金属如何直接影响 Oreochromis niloticus 肝脏和肾脏的抗氧化状态？一项体外研究。

背景

金属会干扰鱼类生理和生化机制的完整性。因此，作为抗氧化系统的防御成分是重要的生物标志物，因为它们在应对金属压力方面发挥着重要作用。本研究的目的是研究 Cd、Cu 和 Zn 亚致死暴露（体外）对尼罗罗非鱼肝脏和肾脏抗氧化系统参数的直接影响。

方法

在体外亚致死金属（200 和 400 μg/L Cd、Cu 和 Zn）处理尼罗罗非鱼肝和肾上清液后，分析了抗氧化酶活性和 GSH 水平。

结果

由于浓度、金属和组织类型，即使在较低水平的金属也会引起抗氧化系统参数水平的显着变化。GSH 代谢参数对金属效应更敏感。TBARS 水平和 GPX 活性大多增加，而 CAT、SOD、rGSH 和 GSH/GSSG 水平降低。在体外条件下，肾脏比肝脏受到的影响更大。铜对肝脏更有效，而锌对肾脏更有效。Cd 引起抗氧化酶之间的负相关。在锌和铜暴露后，酶和谷胱甘肽水平之间存在显着相关性。

结论

由于其性质和组织差异，直接金属效应可能会触发不同的响应趋势。目前的数据提供了关于哪些抗氧化生物标志物可以更好地定义由直接金属效应引起的氧化应激的知识，以供进一步研究，包括体内实验。