الفهرس 
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Abstract
Background: Silver nanoparticles became one of the most manufactured nanomaterials introduced in the medicine field, that’s why it was mandatory to evaluate their biological toxicity.
Aim of the study: In this study, the aim was to evaluate the size-dependent toxicity of intraperitoneal administered characterized Ag NPs of different sizes on the submandibular salivary glands of adult albino rats.
Methodology: Fifty adult male albino rats were randomized into three groups: group 1 (control), group 2 received intraperitoneal injection of 13mg/kg body weight of Ag NPs (10 nm), and group 3 received intraperitoneal injection of 13mg/kg body weight of Ag NPs (60 nm). The rats were sacrificed after 3 and 6 hours from treatment. The submandibular salivary glands of the all groups
were subjected to histopathological examination, histomorphometric analysis,
immunohistochemical examination, real time PCR analysis, colorimetric assay, and ultrastructural examination.
Results: Histologically, the submandibular salivary glands of group 2 revealed sign of acinar degeneration, represented by loss of normal architecture (amalgamation), intracytoplasmic vacuolization. The nuclei of the acinar cells revealed pleomorphism and pyknosis. However, the seromucous acini were relatively preserved their shape in group 3. Immunohistochemical examination showed significant increase in active caspase-3 immunoreactivity in all Ag NP-treated
groups. RT-PCR results revealed significantly decreased GPx mRNA gene expression in all Ag NP-treated groups, while colorimetric assessment revealed significantly decreased GSH levels and increased MDA levels in all Ag NP-treated groups.
Ultrastructurally, the seromucous acini of group 2 revealed intracytoplasmic vacuolization, pyknotic nuclei, interrupted nuclear envelope, degenerated mitochondria, lacerated rough endoplasmic reticulum and dilated smooth endoplasmic reticulum. However, the sign of acinar degeneration was relatively mild in group 3.
Conclusion: In a rat model, Ag NP induced cytotoxic effect. The cytotoxic effect was size- and time-dependence.