Antioxidative indices and liver histology of rainbow trout (Oncorhynchus mykiss) fed diets containing nickel oxide nanoparticles and silymarin

Recent nano-technological developments have resulted in outstanding industrial developments in one hand and aroused concerns regarding their discharge into water bodies and subsequent toxicity to aquatic lives in the other hand. This study evaluated the antioxidative indices and liver histology of rainbow trout (Oncorhynchus mykiss) fed diets containing nickel oxide nanoparticles and silymarin. Therefore, 1200 fish (3.83±0.01g) were randomly allotted into 8 distinct treatments including control group and seven other experimental groups receiving various levels of dietary nickel oxide nanoparticles (0, 100 and 500 mg/kg feed) and silymarin (0 and 1 g/kg feed). The experiment lasted for 60 days with 3 respective replicates. Results showed that the total antioxidative capacity of various experimental groups did not significantly differ (P>0.05), whilst catalase showed significantly different levels of activity amongst various treatments (P≤0.05). Glutathione peroxidase did not show considerable differences among experimental groups, on the contrary superoxide dismutase had significantly different activities among treatments (P≤0.05). Histological examinations revealed that preventive and curative administration of nickel oxide nanoparticles did not have considerable positive effects on curbing pathological outcomes of nanoparticles on the tissue. However, to elucidate a comprehensive conclusion in this regard, further studies concerning various silymarin inclusion levels and exposure time are required.