The cytological and electrophysiological effects of silver nanoparticles on neuron-like PC12 cells

The aim of this study was to investigate the toxic effects and mechanism of silver nanoparticles (SNPs) on the cytological and electrophysiological properties of rat adrenal pheochromocytoma (PC12) cells. Different concentrations of SNPs (20 nm) were prepared, and the effects of different application durations on the cell viability and electrical excitability of PC12 quasi-neuronal networks were investigated. The effects of 200 μM SNPs on the neurite length, cell membrane potential (CMP) difference, intracellular Ca(2+) content, mitochondrial membrane potential (MMP) difference, adenosine triphosphate (ATP) content, and reactive oxygen species (ROS) content of networks were then investigated. The results showed that 200 μM SNPs produced grade 1 cytotoxicity at 48 h of interaction, and the other concentrations of SNPs were noncytotoxic. Noncytotoxic 5 μM SNPs significantly increased electrical excitability, and noncytotoxic 100 μM SNPs led to an initial increase followed by a significant decrease in electrical excitability. Cytotoxic SNPs (200 μM) significantly decreased electrical excitability. SNPs (200 μM) led to decreases in neurite length, MMP difference and ATP content and increases in CMP difference and intracellular Ca(2+) and ROS levels. The results revealed that not only cell viability but also electrophysiological properties should be considered when evaluating nanoparticle-induced neurotoxicity. The SNP-induced cytotoxicity mainly originated from its effects on ATP content, cytoskeletal structure and ROS content. The decrease in electrical excitability was mainly due to the decrease in ATP content. ATP content may thus be an important indicator of both cell viability and electrical excitability in PC12 quasi-neuronal networks.