Exposure to silver nanoparticles induces oxidative stress and memory deficits in laboratory rats

Abstract

Currently most of the applications of silver nanoparticles are in antibacterial/antifungal agents in medicine and biotechnology, textile engineering, water treatment and silver-based consumer products. However, the effects of silver nanoparticles on human body, especially on the central nervous system, are still unclear. To study the mechanisms underlying the effects of silverpoly(amidehydroxyurethane) coated silver nanoparticles on brain functions, we subjected male Wistar rats to chronic treatments with silver-29 nm (5 µg/kg and 10 µg/kg) and silver-23 nm (5 µg/kg and 10 µg/kg) nanoparticles for 7 days. We evaluated the effects of nanoparticles size and structure on rat memory function. Memory processes were studied by means of two cognitive tasks (Y-maze and radial arm-maze). Exposure to silver nanoparticles significantly decreased spontaneous alternation in the Y-maze task and working memory functions in the radial arm-maze task, suggesting that nanoparticles have effects on short-term memory. We found no effects on long-term memory, which we assessed by reference memory trials in the radial arm-maze task. We found that memory deficits were significantly correlated with oxidative stress generation only in the Y-maze task. Our findings suggest that silver nanoparticles may induce an impairment of memory functions by increasing oxidative stress in the brain. The use of silver nanoparticles for medical purposes therefore requires careful consideration, particularlyif it involves exposure of the human brain.

Nanosilver – Harmful effects of biological activity

“…Funkcje poznawcze w testach behawioralnych labiryntu Y i labiryntu promienistego badano u szczurów po 7 dniach dootrzewnowej ekspozycji na nanocząstki srebra (44). Narażenie na nanocząstki wyraźnie pogorszyło funkcje spontanicznej zmienności w teście labiryntu Y oraz pamięci roboczej w teście labiryntu promienistego, wskazując na zaburzenia pamięci krótkotrwałej u szczurów.…”

“…Nie stwierdzono natomiast wpływu na pamięć długotrwałą, mierzoną próbą pamięci referencyjnej w teście labiryntu promienistego. Eksperymentatorzy sugerują, że indukowane naraże-niem na nanocząstki srebra zaburzenia pamięci zachodzą pod wpływem stresu oksydacyjnego w komórkach mózgu (44).…”

Attenuated effects of chitosan-capped gold nanoparticles on LPS-induced toxicity in laboratory rats

“…Dark field imaging was performed to visualize the location of AuNP in the brain. During the analysis, the identity of each slide was unknown to the pathologist, following standard laboratory procedures [32].…”

“…The ratio of liver and brain to body weight was calculated as follows: wet liver weight (mg)/wet body weight (g) and wet brain weight (mg)/wet body weight (g), respectively [20,32].…”

Silver nanoparticles: Electron transfer, reactive oxygen species, oxidative stress, beneficial and toxicological effects. Mini review

“…A related study with rat brain also revealed gene expression in the cortex and hippocampus were altered due to OS caused by AgNPs (Huang, Hsiao, Lin, Wang, & Huang, 2015;Rahman et al, 2009). Intraperitoneal injection of AgNPs from 23 up to 29 nm size in laboratory rats, inhibited AO SOD and GSH production in the cortex due to OS, and showed short-term memory loss and poor performance in behavioral tests (Hritcu et al, 2011). Gonzalez-Carter and co-workers showed AgNPs reduce brain inflammation and related neurotoxicity through induction of hydrogen sulfide (H 2 S)-synthesizing enzymes (Gonzalez-Carter et al, 2017).…”