Hazardous Effects of SiO2 Nanoparticles on Liver and Kidney Functions, Histopathology Characteristics, and Transcriptomic Responses in Nile Tilapia (Oreochromis niloticus) Juveniles

Abstract

The current investigation assessed the impacts of sub-lethal concentrations of silicon dioxide nanoparticles (SiO₂NPs) on hepato-renal functions, histopathological characteristics, and gene transcription in gills and liver of Nile tilapia juveniles. Fish were exposed to 20, 40, and 100 mg/L of SiO₂NPs for 3 weeks. Pairwise comparisons with the control group showed a significant dose-dependent elevation in serum ALP, ALT, and AST enzyme activities as well as blood urea and creatinine levels in SiO₂NP-intoxicated groups. Exposure to 100 mg/L SiO₂NPs significantly upregulated expression of <i>HSP70</i>, <i>TNF-α</i>, <i>IL-1β</i>, and <i>IL-8</i> genes in the gills as compared to the control group. Moreover, exposure to 100 mg/L SiO₂NPs significantly upregulated the expression <i>SOD</i>, <i>HSP70</i>, <i>IL-1β</i>, <i>IL-8</i>, and <i>TNF-α</i> genes in the hepatic tissues as compared to the control group. Exposure of fish to 20 mg SiO₂NPs/L significantly increased the mRNA expression levels of <i>IL-12</i> in both the gills and liver tissues. Notably, all tested SiO₂NP concentrations significantly upregulated the transcription of <i>CASP3</i> gene in gills and liver of Nile tilapia as compared to the control group. Interestingly, varying histopathological alterations in renal, hepatopancreatic, and branchial tissues were observed to be correlated to the tested SiO₂NP concentrations. In conclusion, our results provide additional information on the toxic impacts of SiO₂NPs in Nile tilapia at the hematological, tissue, and molecular levels.