Figure 4

AgNPs induce reduction or alteration of cytoskeletal components, β-tubulin and F-actin, in rat cortical primary cultures. We first assessed the effect of AgNPs on neuronal cytoskeleton initiation and outgrowth in cells cultured either in the absence (control) or presence of different concentrations of AgNPs for 3 days (A-E, via a 20× objective). We also examined whether AgNPs could affect well-established cytoskeleton network in cells that have been cultured for 4 days and were then exposed to various concentrations of AgNPs (F-J, via a 63× oil objective). In both sets of experiments, control neurons displayed high fluorescence intensity of β-tubulin (green) and F-actin (red), which labeled healthy cell bodies and dense neuritic overlaps. AgNP-treatment increased cell death in combination with a reduction in β-tubulin branching and overlapping (also see inserted phase contrast images). AgNPs also reduced the degree and intensity of red fluorescent labeling of F-actin in AgNP-treated cultures.