Key Laboratory of Marine Biotechnology of Fujian Province, Institute of Oceanology, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
Key Laboratory of Marine Biotechnology of Fujian Province, Institute of Oceanology, Fujian Agriculture and Forestry University, Fuzhou 350002, China; Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai 519000, China.
Aquat Toxicol. 2021 Dec;241:106014. doi: 10.1016/j.aquatox.2021.106014. Epub 2021 Oct 29.
Cadmium (Cd) is a ubiquitous environmental contaminant, posing serious threats to aquatic organisms. The aims of the present study were to investigate the effects of long-term Cd exposure on the growth, GH/IGF axis, antioxidant defense and DNA methylation in juvenile Nile tilapia (Oreochromis niloticus). To this end, juvenile Nile tilapia were exposed to 0, 10 and 50 µg∙L Cd for 45 and 90 days. The obtained results revealed that exposure to high concentrations of Cd significantly decreased body mass and body length, and down-regulated mRNA levels of GHRs, IGF-I and IGF-II in the liver of Nile tilapia. Cd exposure induced oxidative stress including the reduction of antioxidant activities and increases of malondialdehyde (MDA) and 8-hydroxydeoxyguanosine (8-OHdG) contents. Beside, the global DNA methylation levels significantly decreased with increasing Cd concentration and exposure time, which might result from increased oxidative DNA damage, the down-regulated expression of DNMT3a and DNMT3b and up-regulated expression of TET1 and TET2. In conclusion, long-term Cd exposure could inhibit growth, reduce antioxidant capacity and lead to oxidative damages to lipid and DNA, and decrease global DNA methylation level in juvenile Nile tilapia.
镉（Cd）是一种普遍存在的环境污染物，对水生生物构成严重威胁。本研究旨在探讨长期暴露于镉对幼尼罗罗非鱼（Oreochromis niloticus）生长、GH/IGF 轴、抗氧化防御和 DNA 甲基化的影响。为此，将幼尼罗罗非鱼暴露于 0、10 和 50μg·L Cd 中 45 和 90 天。结果表明，高浓度 Cd 暴露显著降低了幼尼罗罗非鱼的体质量和体长，下调了肝脏中 GHRs、IGF-I 和 IGF-II 的 mRNA 水平。Cd 暴露诱导了氧化应激，包括抗氧化活性的降低以及丙二醛（MDA）和 8-羟基脱氧鸟苷（8-OHdG）含量的增加。此外，随着 Cd 浓度和暴露时间的增加，总 DNA 甲基化水平显著降低，这可能是由于氧化 DNA 损伤增加、DNMT3a 和 DNMT3b 的表达下调以及 TET1 和 TET2 的表达上调所致。综上所述，长期暴露于 Cd 可抑制幼尼罗罗非鱼的生长，降低抗氧化能力，导致脂质和 DNA 氧化损伤，并降低其总 DNA 甲基化水平。
