Zinc protects the rat brain from damage induced by 24 h exposure to silver nanoparticles

Silver nanoparticles (AgNPs) have been widely employed due to their antimicrobial properties; however, several studies sustain that AgNPs can induce brain damage, like the blood-brain barrier (BBB) disruption. Among the BBB defense mechanisms, the metallothioneins (MTs), a collection of proteins that regulate intracellular levels of zinc (Zn), play an important role. The goal of this work was to investigate whether the brain damage caused by an intraperitoneal administration of AgNPs (15 mg/ g body weight) at the level of the BBB permeability disruption, damage of the brain tissue, and systemic inflammation could be prevented by 24 h of previous treatment with Zn (27 mg/kg body weight). Evans blue (EB) extravasation, modification of claudin-5 expression, alterations on MTs, N-cadherin expression, and systemic inflammation were evaluated. Our results show that AgNPs induce BBB damage by increasing EB extravasation and decreasing claudin-5 expression, associated with overexpression of MTs, effects that were related with systemic inflammation, evidenced by the increase of granulocytes. Zn pretreatment partially prevented the BBB permeability from the damage induced by AgNPs, whereas the MTs expression and granulocytes count exhibited a reversal effect, suggesting that the effect of Zn could be related with the BBB regulation process. The rat brain histological analysis confirmed that pretreatment with Zn prevented at least in part the toxic effect of AgNPs. This work provides relevant information about the role of Zn as a protectant against the noxious effects of AgNPs upon the rat brain physiology.