Department of Integrative Biology, Oklahoma State University, Stillwater, OK, USA.
Department of Integrative Biology, Oklahoma State University, Stillwater, OK, USA; Department of Earth and Planetary Sciences, Washington University, Saint Louis, MO, USA.
Ecotoxicol Environ Saf. 2021 Mar 15;211:111930. doi: 10.1016/j.ecoenv.2021.111930. Epub 2021 Jan 17.
Emerging research in mammalian cells suggests that ionic (AgNO) and nano silver (AgNP) can disrupt the metabolism of selenium which plays a vital role in oxidative stress control. However, the effect of silver (Ag) on selenoprotein function in fish is poorly understood. Here we evaluate the effects of AgNO and citrate coated AgNP (cit-AgNP) on selenoprotein function and oxidative stress using a fish cell line derived from the rainbow trout (Oncorhynchus mykiss) intestine (RTgutGC). Cell viability was evaluated using a cytotoxicity assay which measures simultaneously metabolic activity, membrane integrity and lysosome integrity. Cells exposed to equimolar amounts of AgNO and cit-AgNP accumulated the same amount of silver intracellularly, however AgNO was more toxic than cit-AgNP. Selenoenzymes glutathione peroxidase (GPx) and thioredoxin reductase (TrxR) mRNA levels and enzyme activity were measured. While mRNA levels remained unaffected by AgNO or cit-AgNP, the enzyme activity of GPx was inhibited by AgNO (1 µM) and cit-AgNP (5 µM) and TrxR activity was inhibited by AgNO (0.4 µM) and cit-AgNP (1, 5 µM). Moreover, cells exposed to 1 µM of AgNO and cit-AgNP showed an increase in metallothionein b (MTb) mRNA levels at 24 h of exposure, confirming the uptake of silver, but returned to control levels at 72 h suggesting silver scavenging by MTb. Oxidative stress was not observed at any of the doses of AgNO or cit-AgNP tested. Overall, this study shows that AgNO or cit-AgNP can inhibit the activity of selenoenzymes but do not induce oxidative stress in RTgutGC cells.
哺乳动物细胞的新兴研究表明，离子银（AgNO）和纳米银（AgNP）可以破坏硒的新陈代谢，而硒在控制氧化应激中起着至关重要的作用。然而，银（Ag）对鱼类中硒蛋白功能的影响知之甚少。在这里，我们使用源自虹鳟鱼（Oncorhynchus mykiss）肠道的鱼类细胞系（RTgutGC）评估 AgNO 和柠檬酸涂层的 AgNP（cit-AgNP）对硒蛋白功能和氧化应激的影响。细胞活力通过细胞毒性测定法进行评估，该测定法同时测量代谢活性、膜完整性和溶酶体完整性。暴露于等摩尔量的 AgNO 和 cit-AgNP 的细胞在细胞内积累相同量的银，但 AgNO 比 cit-AgNP 更具毒性。测量了硒酶谷胱甘肽过氧化物酶 (GPx) 和硫氧还蛋白还原酶 (TrxR) 的 mRNA 水平和酶活性。虽然 AgNO 或 cit-AgNP 对 mRNA 水平没有影响，但 GPx 的酶活性被 AgNO（1 μM）和 cit-AgNP（5 μM）抑制，TrxR 活性被 AgNO（0.4 μM）和 cit-AgNP（1、5 μM）抑制。此外，暴露于 1 μM 的 AgNO 和 cit-AgNP 的细胞在暴露 24 小时后 MTb 基因的 mRNA 水平增加，证实了银的摄取，但在 72 小时后恢复到对照水平，表明 MTb 对银的清除。在测试的任何剂量的 AgNO 或 cit-AgNP 下都没有观察到氧化应激。总的来说，这项研究表明，AgNO 或 cit-AgNP 可以抑制硒酶的活性，但不会在 RTgutGC 细胞中诱导氧化应激。
