Histological, Histometric and biochemical alterations of the gill and kidney of rainbow trout (Oncorhynchus mykiss) exposed to silver nanoparticles

Regarding fast development of the nanotechnology and its diverse applications, is very important having enough data on the probably its side effects on the aquatic body organs. Therefore, these studies investigate the effects of nanosilver administration on histology of gill and kidney biochemical parameters in rainbow trout. For this study, the silver nanoparticles were synthesized in a one-step reduction process in an aqueous solution. 60 O. mykiss were obtained from a local commercial hatchery. Fish were divided randomly into four groups. Control group was kept in dechlorinated tap water without any add-on material, while experimental groups were exposed to concentration of 3, 300 and 1000 mg/L of nanosilver solution, respectively for eight weeks. At the end of experiments, blood samples were collected and biochemical analyses of sera were performed. Tissue samples were also taken and histological alterations of the gill and kidney were examined. In the gill tissues of the exposed fish to nanosilver; aneurism in the secondary lamellae of gills, hyperplasia of epithelium of gills as well as the adhesion of the gill lamellae were seen, as compared with control animals. In addition, treating with silver nanosilver could induce hyaline cast formation, signisicant decreasing in the glomerular diameter and also formation of intra cytoplasmic vacuoles in the various urinary tubules. The serum levels of total protein was decreased significantly (P<0.05) by increasing nanosilver concentration. Other parameters such as ALP, LDH, AST and ALT levels in sera of nanosilver treated fish showed a significant increase compare to the control group (P<0.05). It is concluded that nanosilver induces gill and kidney damages and changes in serum biochemical parameters of O. mykiss juveniles in different concentrations.