Sarkar Olivia, Islam Shehnaz, Mukherjee Sunanda, Chattopadhyay Ansuman
Department of Zoology, Visva-Bharati, Santiniketan, West Bengal, India.
J Appl Toxicol. 2025 Jul;45(7):1331-1347. doi: 10.1002/jat.4776. Epub 2025 Mar 12.
The extensive industrial use of lead (Pb) and chromium (Cr) has led to their persistent release into aquatic ecosystems, posing severe ecological and toxicological challenges. While the individual toxicities of these metals are well-documented, their combined effects, particularly on toxicity mechanisms and cellular stress responses, remain inadequately understood. This study investigated the hepatotoxic effects of Pb and Cr, both individually and in combination, in zebrafish (Danio rerio), focusing on oxidative stress and the Nrf2-Keap1-ARE signaling pathway. Zebrafish were exposed to environmentally relevant concentrations of Pb (2.5, 5, and 10 ppb), Cr (0.5, 1, and 2 ppm), and their combination for 15, 30, and 60 days. Combined exposure elicited heightened oxidative stress, marked by elevated reactive oxygen species, lipid peroxidation, catalase activity, and a significant reduction in glutathione levels. Histopathological analysis revealed severe alterations, including vacuolation, sinusoidal dilation, and necrosis, with the most pronounced effects observed in the combined exposure groups. Gene expression analysis demonstrated the upregulation of oxidative stress-related genes (nrf2, ho1, nqo1, gpx1, catalase, gst, cu/znsod, mnsod, and cyp1a) and heat shock protein (hsp70) and the downregulation of keap1, and ucp2, particularly in co-treated groups. Immunofluorescence observation confirmed enhanced nuclear translocation of Nrf2, while atomic absorption spectrophotometry studies revealed significant bioaccumulation of Pb and Cr in the liver, especially during combined exposures. These findings underscore that Pb and Cr co-exposure intensifies oxidative stress and hepatotoxicity via the Nrf2-Keap1-ARE pathway, emphasizing the environmental and health risks associated with heavy metal contamination in aquatic ecosystems.
铅（Pb）和铬（Cr）在工业上的广泛使用导致它们持续释放到水生生态系统中，带来了严峻的生态和毒理学挑战。虽然这些金属的单一毒性已有充分记录，但它们的联合效应，特别是对毒性机制和细胞应激反应的影响，仍未得到充分了解。本研究调查了铅和铬单独及联合作用对斑马鱼（Danio rerio）的肝毒性作用，重点关注氧化应激和Nrf2-Keap1-ARE信号通路。将斑马鱼暴露于环境相关浓度的铅（2.5、5和10 ppb）、铬（0.5、1和2 ppm）及其组合中15、30和60天。联合暴露引发了氧化应激加剧，表现为活性氧升高、脂质过氧化、过氧化氢酶活性增加以及谷胱甘肽水平显著降低。组织病理学分析显示出严重改变，包括空泡化、窦状扩张和坏死，联合暴露组的影响最为明显。基因表达分析表明，氧化应激相关基因（nrf2、ho1、nqo1、gpx1、过氧化氢酶、gst、cu/znsod、mnsod和cyp1a）和热休克蛋白（hsp70）上调，而keap1和ucp2下调，特别是在联合处理组中。免疫荧光观察证实Nrf2的核转位增强，而原子吸收分光光度法研究显示肝脏中铅和铬有显著生物蓄积，尤其是在联合暴露期间。这些发现强调，铅和铬共同暴露通过Nrf2-Keap1-ARE途径加剧氧化应激和肝毒性，突出了水生生态系统中重金属污染相关的环境和健康风险。
