Abstract
Background: The excessive exposure to silver nanoparticles (Ag-NPs) has raised concerns about their possible risks to the human health. The brain is a highly vulnerable organ to nano-silver harmfulness. The aim of this work was to evaluate the impacts of Ag-NPs exposure on the cerebellar cortex of rats. Methods: Rats were assigned to: Control, vehicle control and Ag-NP-exposed groups (at doses of 10 mg and 30 mg/kg/day). Samples were processed for light and electron microscopy examinations. Immunohistochemical localization of c-Jun N-terminal kinase (JNK), nuclear factor kappa beta (NF-κB) and calbindin D28k (CB) proteins was performed. Analyses of expression of DNA damage inducible transcript 4 (Ddit4), flavin containing monooxygenase 2 (FMO2) and thioredoxin-interacting protein (Txnip) genes were done. Serum levels of inflammatory cytokines were also measured. Results: Ag-NPs enhanced apoptosis as evident by upregulation of Ddit4 gene expressions and JNK protein immune expressions. Alterations of redox homeostasis were verified by enhancement of Txnip and FMO2 gene expressions, favoring the activation of inflammatory responses by increasing NF-κB protein immune expressions and serum inflammatory mediator levels. Another cytotoxic effect was the reduction of immune expressions of the calcium regulator CB. Conclusion: Ag-NPs exposure provoked biochemical, cellular and molecular changes of rat cerebellar cortex in a dose-dependent manner.
Highlights
The innovation of nanomaterials has evoked advancements in science and engineering research
Scanning Electron Microscopy (SEM) image and Energy Dispersive X-Ray (EDX) spectrum analyses indicated the presence of considerable amounts of Ag-NPs in the cerebellar cortex, which increased in a dose-dependent manner in the exposure groups (Figure 3)
Stained sections for calbindin D28k (CB) of control group showed positive cytoplasmic immune reaction in most of Purkinje cells (Figure 5A), few immune reactive cells were detected in low-dose group (Figure 5B), while the reactions were nearly absent in high-dose group (Figure 5C)
Summary
The innovation of nanomaterials has evoked advancements in science and engineering research. Nanomaterials are considered the materials for future owing to their distinctive properties and varied applications [1]. Silver nanoparticles (Ag-NPs) are among the most hazardous metal nanoparticles due to the extensive uses and the inevitable exposure of human. They have been widely used in the production of cosmetics, healthcare products and wound dressings. They have antibacterial efficacy and more recently, synergistic effects with antibiotics against resistant bacterial species [2].
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