Comparative toxicity of silver nanoparticle and ionic silver in juvenile common carp (Cyprinus carpio): Accumulation, physiology and histopathology

Highlights: • 96-h LC₅₀ concentration of AgNPs and AgNO₃ were 0.29 ± 0.02 and 0.15 ± 0.05 mg/L, respectively. • Highest concentration of total silver was observed in liver of common carp exposed to AgNPs. • AgNO₃ exhibited more stress response than AgNPs. • Highest expressions of growth related genes were observed in common carp exposed to AgNPs. • Different tissue lesions were observed in exposed groups and highest damages were related to the gill. - Abstract: Many studies have investigated the potential negative effects of silver on aquatic organisms, but most focused on short-term exposure in few species. Moreover, there are many uncertainties about differences in potential toxicity mechanisms and adverse effects of silver nanoparticles (AgNPs) and ionic form of silver (AgNO₃). We investigated chronic effects of AgNPs and AgNO₃ on the juvenile common carp (Cyprinus carpio). AgNPs and AgNO₃ accumulated in the liver, gill and intestine, respectively and highest was related to AgNPs. Our results indicated, silver uptake was accompanied with histological alteration in the target organs such that different tissue lesions were observed in exposed groups. Superoxide dismutase (SOD), catalase (CAT) and lactate dehydrogenase (LDH) activity and also hsp70, ghrelin and IGF-1 genes expression were induced in both forms. After 7 days, highest hsp70 gene expression was observed in AgNO₃ treatment and highest ghrelin and IGF-1 gene expression was observed in AgNPs treatment. The results revealed that adverse effects of AgNPs on different aspects of the health of juvenile common carp, may not be solely a result of particle dissolution. In addition, the main toxic mechanism of AgNPs was probably related to the accumulation of silver followed by the molecular and oxidative stress response.