The effects of exposure to nanosilver via the maternal milk on the brain of newborn rats

Today, nanosilver have a wide range of applications in personal care products, food processing and medical fields because of its antimicrobial properties. Recent studies have revealed that nanoparticles are able to transfer from mothers to their offspring via the placenta and maternal milk and accumulate into various organs, including brain. Since oxidative stress is a key mechanism for nanoparticles toxicity and the developing brain is highly vulnerable to oxidative stress, in this study, we evaluated the potential of nanosilver to induce oxidative stress in the rat offspring brain. The lactating mothers were divided into the treated and control groups that were treated orally with nanosilver (25 mg/kg BW) and deionized water (from 1th to 12th days of lactation), respectively. The offspring's brains were collected on postnatal day 13. For histopathological studies, some of the brains were sliced and stained with hematoxylin and eosin. The levels of Malondialdehyde, Glutathione, Glutathione peroxidase activity and silver accumulation in offspring's brains were determined using spectrophotometric assay and ICP-MS analysis, respectively. The high numbers of microvacuolar structures, significant increase in silver content and Malondialdehyde level (p<0.001) and significant decrease in Glutathione peroxidase activity and Glutathione level (p<0.05) was observed in the offspring brain of the treated group compared with those in the control group. The results showed that accumulation of silver in the brain might cause oxidative stress via reduction of the capacity of the antioxidant defense mechanism. However, further experiments should be carried out to clarify these events in details.