Hemato-immunological, serum metabolite and enzymatic stress response alterations in exposed rainbow trout (Oncorhynchus mykiss) to nanosilver

The aim of present study was to investigate the effects of sub-lethal concentrations of silver nanoparticles (AgNP) on hematological parameters, differential tests of white blood cells, serum metabolite parameters, serum enzymes activity and serum ions in rainbow trout,  Oncorhynchus mykiss . Healthy rainbow trout, were exposed to sub-lethal concentrations (0, 1.5 and 2.5 ppm) of nanosilver for 14 days. RBC, WBC and Hct levels were significantly ( P <0.05) increased in exposed groups. Within the white blood cells, only neutrophils showed a significant increase at 7 and 14 days post exposure ( P <0.05). Serum triglyceride, total serum protein, albumin and globulin levels were decreased ( P <0.05) in exposed fish, however, cholesterol levels increased in the 2.5 ppm group at 7 days after exposure ( P <0.05). Cortisol and glucose increased significantly at 7 and 14 days of exposure in both concentrations of AgNPs ( P <0.05). Decreases in serum ions level were observed, although reduction in chloride ions occurred earlier and more severe than other measured parameters ( P <0.05). Elevation in serum ALP, LDH, ALT and AST enzymes were observed during the experiment ( P <0.05), although SOD and CAT activity were significantly decreased in exposed groups ( P <0.05). The results revealed that AgNP can affect the hematological, serum metabolite and enzymatic parameters of  O. mykiss , as well as AgNP exposure induce a general oxidative stress response in O. mykiss.