Effects of Prolonged Silver Nanoparticle Exposure on the Contextual Cognition and Behavior of Mammals

Abstract

Silver nanoparticles have been widely used in the lighting and food industries, in medicine, and in pharmaceutics as an antiseptic agent. Recent research demonstrates that, after prolonged oral administration, silver nanoparticles may cross the blood-brain barrier and accumulate in the brain in rather high amounts. In ex vivo experiments, it has also been shown that silver nanoparticles demonstrate neurotoxicity. The objective of this work was to answer the questions whether silver nanoparticles change cognitive and behavioral functions of mammals after prolonged administration if silver nanoparticles have accumulated in the brain. C57Bl/6 male mice were orally exposed to PVP-coated silver nanoparticles daily for 30, 60, 120 and 180 days. Control mice were exposed to distilled water. After that they were tested in the Open Field, Elevated Plus Maze, Light-Dark Box and contextual fear conditioning task. The data have shown that the experimental mice went through three periods of switching in the behavior caused by adaptation to the toxic silver nanoparticles: anxiety, appearance of research instinct and impairment of long-term memory. This provides evidence of the hazardous effect of silver nanoparticles, which appears after long periods of silver nanoparticle oral administration.

The Effect of Silver Nanoparticles on Learning, Memory and Social Interaction in BALB/C Mice

“…Recently, Węsierska et al reported that oral gavage with a dose of 1 mg/kg of AgNPs produced adverse effect on memory and cognitive function [32]. In addition, Antsiferova et al investigated the effects of the prolonged oral administration of PVP-coated AgNPs at the dosage of 50 μg per day demonstrating impairment of long-term memory [33].…”

Disturbance in Mammalian Cognition Caused by Accumulation of Silver in Brain

“…Since the beginning of the 2000s, silver nanoparticles (Ag-NPs) have been used in various applications from pharmaceutics [ 1 , 2 , 3 , 4 ] to textiles [ 5 , 6 , 7 ] and from hygiene products [ 8 ] and packing materials [ 9 ] to daily food supplements [ 10 , 11 , 12 , 13 , 14 ]. Undoubtedly, Ag possesses unique antiseptic properties that have been known since antiquity [ 15 ].…”

Mitochondrial Peptide Humanin Protects Silver Nanoparticles-Induced Neurotoxicity in Human Neuroblastoma Cancer Cells (SH-SY5Y)

“…ER stress and UPR activate important proteins such as the inositol requiring protein 1 (IRE1), PKR-like endoplasmic reticulum kinase (PERK), and activating transcription factor-6 (ATF-6) which act as stress sensing proteins and are early markers for ER stress induced nanotoxicity [43]. Prolonged exposure of C57Bl/6 male mice to AgNPs causes contextual cognition and behavior anomalies in mammals [44]. Neurotoxicity induced by nanoparticles causes adverse effects on the structure, function or chemistry of the nervous system by increasing level of ROS, elevation of cytokines, and dysregulation of apoptosis leading to neuronal death [45,46].…”