Histopathology of dietary exposure to the selenium and iron nanoparticles on the liver tissue of reared beluga, Huso huso

This study aimed to investigate the effects of different levels of selenium nanoparticles (Se-NPs) and iron nanoparticles (Fe-NPs) on histopathology of the liver in the beluga juvenile, Huso huso. A total of 135 beluga juveniles (with initial weight of 276.4 ± 32.3 g and initial length of 40.0 ± 2.0 cm) were randomly distributed in 27 fiberglass tanks at 9 different treatments with three replicates. Treatments included T1 (control, no added NPs); T2 (1 mg/kg Se-NPs); T3 (2 mg/kg Se-NPs); T4 (100 mg/kg Fe-NPs); T5 (100 mg/kg Fe-NPs + 1 mg/kg Se-NPs); T6 (100 mg/kg Fe-NPs +2 mg/kg Se-NPs); T7 (200 mg/kg Fe-NPs); T8 (200 mg/kg Fe-NPs +1 mg/kg Se-NPs); T9 (200 mg/kg Fe-NPs +2 mg/kg Se-NPs). Before starting the experiment, the fish were adapted to the rearing conditions for one week. The amount of feeding during the rearing period was 2-3% based on the weight and water temperature, and the fish were fed three times a day (8:00, 15:00 and 21:00) for 8 weeks. In order to find the histopathological changes, the livers of six fish from each group (two fish of each replicate) were sampled at the end of the experiment. Samples were dehydrated by routine methods and embedded in paraffin wax. They were sectioned by microtome and stained with H & E. Vacuolar degeneration, necrosis, inflammation, irregular hepatocytes and hemorrhage were the tissue lesions observed in the liver. Given that, T5 (100 mg/kg Fe-NPs + 1 mg/kg Se-NPs) had the lowest liver tissue damage, using 1 mg selenium nanoparticles with 100 mg iron nanoparticles in the diet of farmed beluga is recommended.