Effect of sub-accute exposure of Cu nanoparticles on histopatological, DNA damage and oxidative enzymes changes in ( Rutilus caspicus Yakovlev, 1870 )

Abstract

The current study has determined the toxicity effects of copper nanoparticles on the some vital organs such as gill, liver and kidney of Caspian Roach; Rutillus caspicus. For this purpose, 120 fishes were used as experimental fishes and exposed to 0.1, 0.2 and 0.5 mg/L of Cu nanoparticles for 21 days, and 30 fishes as control. The mean water temperature of the aquaria was 22±2 ºC, dissolved oxygen 5.2 mg/L, pH at 7±0.004 and the concentration of calcium carbonate was 270 ppm. On the 7, 14 and 21 days after exposing the fishes to Cu nanoparticles, three fish were randomly selected from each aquaria, sacrificed and samples from their gill, liver and kidney were taken and fixed in cold 10 % buffered formalin. Then microscopic sections were prepared and examined by light microscope which showed histological alternations in the gill, liver and kidney tissues. Then blood samples collected for enzymatic and DNA damage evaluation. Histological al-ternation in gills included: hyperplasia, fusion and detachment of secondary lamellae, blood congestion in vascular axis of primary filaments, reduced secondary lamellae length and cellular degeneration. Histolog-ical changes in liver included blood congestion in the central veins, cytoplasmic vacuolation of the hepato-cytes, cellular degeneration, congestion in the blood sinusoids and necrosis of the hepatocytes. Histological changes in kidneys included glomerular shrinkage, severe degeneration in the tubules cells, interstitial tissue and glomerulus, increase in interstitial tissue cells and macrophages aggregation.The most severe alternation of the gill, liver and kidney were in third weeks at 0.5 mg/l concentration. There were positive correlation between concentration and hyperplasia (r=.815, p<.01), fusion (r=.620, p<.05), detachment (r=.849, p<.01), blood congestion (r=.706, p<.05), degeneration (r=.742, p<.01). There were positive correlation between time and telangiectasia (r=.611, p<.05). There were positive correlation between concentration and hepato-cytes hypertrophy (r=.652, p< .01), necrosis (r=.768, p<.05). The activity of antioxidant stress enzymes, superoxide dismutase (SOD) and catalase (CAT), were measured in the specimens. The maximum level of enzymes activities were in first week at 0.1 mg/l concentration. There were significant difference between treatments and control (p<0.05). We used comet assay for evaluation of DNA damage. The activity of anti-oxidant stress enzymes were higher in low concentration. DNA damage was significant in all treatments. The most severe DNA damage have seen in third week at 0.5 mg/l concentration. Evaluation of these changes could be useful in estimating the harmful effects of Copper nanoparticles. The degree of damages was more intensive at higher CuNP concentrations. The result of the study showed that CuNPs could cause severe damages on the Caspian roach; Rutillus caspicus and have lethal effects for fish.