Falfushynska Halina, Gnatyshyna Lesya, Horyn Oksana, Shulgai Arkadii, Stoliar Oksana
Research Laboratory of Comparative Biochemistry and Molecular Biology, Ternopil National Pedagogical University, Kryvonosa Str. 2, 46027 Ternopil, Ukraine.
I.Ya. Horbachevsky Ternopil State Medical University, Maidan Voli 1, 46001 Ternopil, Ukraine.
Saudi J Biol Sci. 2019 Mar;26(3):481-489. doi: 10.1016/j.sjbs.2017.10.004. Epub 2017 Oct 4.
Global decline of amphibian populations causes particular concern about their vulnerability to novel environmental pollutants, including engineering nanomaterials and pharmaceutical products. We evaluated the bioavailability of nanoform of zinc oxide (n-ZnO) in frog and determined whether co-exposure to a common pharmaceutical, a calcium-channel blocker nifedipine (Nfd) can affect this bioavailability. Male frogs were exposed for 14 days to the tap water (Control) and n-ZnO (3.1 μM), Zn (3.1 μM, as a positive control for n-ZnO exposures), Nfd (10 μM), and combination of n-ZnO and Nfd (n-ZnO + Nfd) in environmentally-relevant concentration. Exposure to Zn or n-ZnO led to up-regulation of metal-binding proteins, metallothioneins (MTs) in the liver and Zn-carrying vitellogenin-like proteins in the blood plasma. Notably, upregulation of MTs by Zn or n-ZnO exposures combined with increased binding of Zn and Cu to MTs. This was associated with the more reducing conditions in the liver tissue indicated by elevated lactate to pyruvate ratio. Nfd suppressed the binding of Zn and Cu to MTs and led to a decrease in Lactate/Pyruvate ratio and elevated protein carbonylation indicating pro-oxidant conditions. Redox status parameters were not directly related to DNA fragmentation, nuclear abnormalities or suppression of cholinesterase activity indicating that factors other than oxidative stress are involved in cytotoxicity of different pollutants and their combinations. Furthermore, activity of Phase I biotransformation enzyme (CYP450 oxidase measured as EROD) was elevated in Nfd-containing exposures and in Zn exposed frogs. Tyrosinase-like activity in the frog liver was strongly stimulated by Zn but suppressed by n-ZnO, Nfd and n-ZnO + Nfd. These findings show that Nfd modulates homeostasis of essential metals in amphibians and emphasize that physiological consequences of combined n-ZnO and Nfd exposures are difficult to predict based on the mechanisms of single stressors.
全球两栖动物数量的减少引发了人们对其易受新型环境污染物影响的特别关注，这些污染物包括工程纳米材料和药品。我们评估了青蛙体内纳米氧化锌（n-ZnO）的生物利用度，并确定同时接触一种常见药物——钙通道阻滞剂硝苯地平（Nfd）是否会影响这种生物利用度。将雄性青蛙暴露于自来水（对照）、n-ZnO（3.1 μM）、锌（3.1 μM，作为n-ZnO暴露的阳性对照）、Nfd（10 μM）以及环境相关浓度下的n-ZnO与Nfd组合（n-ZnO + Nfd）中14天。暴露于锌或n-ZnO会导致肝脏中金属结合蛋白、金属硫蛋白（MTs）以及血浆中携带锌的类卵黄生成素蛋白上调。值得注意的是，锌或n-ZnO暴露导致MTs上调，同时锌和铜与MTs的结合增加。这与肝脏组织中乳酸与丙酮酸比值升高所表明的更强还原条件相关。Nfd抑制了锌和铜与MTs的结合，并导致乳酸/丙酮酸比值降低以及蛋白质羰基化增加，表明存在促氧化条件。氧化还原状态参数与DNA片段化、核异常或胆碱酯酶活性抑制没有直接关系，这表明除氧化应激外的其他因素参与了不同污染物及其组合的细胞毒性作用。此外，在含Nfd的暴露组以及锌暴露的青蛙中，I相生物转化酶（以EROD测量的CYP450氧化酶）的活性升高。青蛙肝脏中的酪氨酸酶样活性受到锌的强烈刺激，但受到n-ZnO、Nfd和n-ZnO + Nfd的抑制。这些发现表明，Nfd调节两栖动物体内必需金属的稳态，并强调基于单一应激源的机制难以预测n-ZnO和Nfd联合暴露的生理后果。
