  Due to their antimicrobial properties, silver nanoparticles (AgNPs) are being
used in non-edible and edible consumer products. It is not clear though if
exposure to these chemicals can exert toxic effects on the host and gut
microbiome. Conflicting studies have been reported on whether AgNPs result in
gut dysbiosis and other changes within the host. We sought to examine whether
exposure of Sprague-Dawley male rats for two weeks to different shapes of
AgNPs, cube (AgNC) and sphere (AgNS) affects gut microbiota, select behaviors,
and induces histopathological changes in the gastrointestinal system and brain.
In the elevated plus maze (EPM), AgNS-exposed rats showed greater number of
entries into closed arms and center compared to controls and those exposed to
AgNC. AgNS and AgNC treated groups had select reductions in gut microbiota
relative to controls. Clostridium spp., Bacteroides uniformis,
Christensenellaceae, and Coprococcus eutactus were decreased in AgNC exposed
group, whereas, Oscillospira spp., Dehalobacterium spp., Peptococcaeceae,
Corynebacterium spp., Aggregatibacter pneumotropica were reduced in AgNS
exposed group. Bacterial reductions correlated with select behavioral changes
measured in the EPM. No significant histopathological changes were evident in
the gastrointestinal system or brain. Findings suggest short-term exposure to
AgNS or AgNC can lead to behavioral and gut microbiome changes.
