Toxicity of zinc oxide nanoparticles (ZnO-NPs) in tilapia (Oreochromis mossambicus): tissue accumulation, oxidative stress, histopathology and genotoxicity

• DOI: 10.1007/s13762-018-1807-7
• Publication Date: 2018-05-22T14:01:10Z
• Authors: K. Shahzad; M. Naeem Khan; F. Jabeen; N. Kosour; A. Shakoor Chaudhry; M. Sohail; N. Ahmad
• Keywords: Comet Assay; Oreochromis mossambicus

Zinc oxide nanoparticles (ZnO-NPs) are being widely used in numerous industrial and commercial applications. This study was designed to investigate the possible mechanisms of bioaccumulation, oxidative stress, histopathological alterations and genotoxicity induced by ZnO-NPs to tilapia (Oreochromis mossambicus). The study showed maximum Zn accumulation of 3.0643 mg/kg (p < 0.05) in liver at highest concentration of 1.5 mg/L in T3. ZnO-NPs induced oxidative stress as indicated by the significantly increased LPO level in gills as compared to liver (p < 0.05). The increased lipid peroxidase (LPO) and superoxide dismutase (SOD) levels were observed in gills than liver. Similar results were observed for catalase (CAT) and glutathione (GSH) in gills. In case of histological alterations, gill oedema and hyperplasia, fusion of gill lamellae and thickening of primary and secondary gill lamellae were observed. In liver, necrosis and apoptosis with condensed nuclear bodies and pyknotic nuclei were observed. The genotoxic potential was investigated by evaluating DNA strands break using alkaline comet assay, and significant DNA damage was observed in the erythrocytes when exposed for ZnO-NPs. The % tail DNA was increased with the increasing concentration of ZnO-NPs, and similar pattern was shown in olive tail movement. Overall, we conclude that the ZnO-NPs have the potential to accumulate in the soft tissues, causing respiratory distress such as oxidative stress, induction of antioxidant defence mechanism by raising glutathione (GSH), organ pathology and genotoxicity. These results suggest the potential ecotoxicological effects of nanoparticles in understanding their uptake and effects on aquatic biota.