Impact of green-synthesized silver nanoparticles on cognitive function and fluorescence spectroscopy of redox status in the hippocampus

Silver nanoparticles exposure is inevitable due to their use in medical products and the food industry. They cross the blood–brain barrier and accumulate in the cerebrum and little information is available regarding their neurotoxicity. We investigated the potential alterations in hippocampal cognitive function and redox status after exposure to green-synthesized silver nanoparticles (AgNPs). The AgNPs was synthesized by Myrtle leaf extracts. After the stereotaxic surgery, the effects of different doses of intra-cerebroventricular-AgNPs administration were evaluated on spatial working memory, passive avoidance test, novel object recognition, and anxiety in male Wistar rats. The hippocampal malondialdehyde levels, and superoxide dismutase activity along with the lipophilic fluorescent products (LFPs) that are end products of lipid peroxidation were measured. The AgNPs had spherical, triangular, and hexagonal shapes with no aggregation. The average diameter size of AgNPs was 91.68 nm and the charge status was -17.4 mV. The AgNPs (1, 10, and 100 ppm) caused the memory impairment and induced anxiety-like behaviors. They raised the malondialdehyde and lowered the superoxide dismutase activity. Higher LFPs were identified in the hippocampus. Low dose of AgNPs (0.1 ppm) maintained hippocampal redox homeostasis and caused no cognitive decline. AgNPs (10 and 100 ppm) induced the high levels of LFPs, impaired memory, and altered the hippocampal redox homeostasis but the low dose (0.1 ppm) did not. Determining the pattern of variations in the spectrum of LFP fluorescent may introduce new indices for determining the nanoparticles toxicity and to make future safe classes of AgNPs in food and drug industries.