Acute Toxicity Study of Nanosilver Particles in Tilapia (Oreochromis niloticus): Pathological Changes, Particle Bioaccumulation and Metallothionien Protein Expression

Abstract

An acute toxicopathological study of silver nanoparticles (AgNPs) was conducted in concentrations of 0, 1, 10 and 100 ppm in adult tilapia (Oreochromis niloticus) at days 0, 1, 2, 3 and 4. Mortality, clinical sign, histopathology and immunohistochemistry were observed and evaluated. Calculated LC₅₀ at 24 hr was 53 ppm. The major clinical sign was respiratory distress. Histopathologic lesions were found mainly in gill, kidney, spleen and liver. Severity of the lesions depended on the concentration and exposure time. Superoxide dismutase (SOD) positive immunostaning was found in gill and renal tubular epithelium. Metallothionein (MT) positive staining was observed in renal tubular epithelium. Autometallography (AMG) positive grains were found in gill and gastrointestinal tract. In summary, AgNPs could cause acute toxicity to tilapia in a concentration and exposure time-dependent manner. Oxidative stress may be involved in the pathogenesis of acute AgNPs exposure. Moreover, the expression of MT in tissues responded to AgNPs accumulation.