Cytotoxicity Of Single-walled Carbon Nanotubes On PC12 Cells

Carbon nanotubes(CNTs) as new nanomaterials have been applied widely in both industrial and biomedical fields. However, compared to the abundant literature dealing with the synthesis, characterization and possible applications of CNTs, it is striking to note the few data on their potential effect on human health. Studies on the potential hazards of CNTs have mainly focused on inhalation and epidermal exposure. Scientis have presumed that CNTs can across the blood brain barrier and impact on the central nervous system. Here, we selected rat PC 12 cells which retain dopaminergic characteristics as a model of neuronal cells to investigate the effect of two kinds commercially available SWCNTs on nervous system. Vitamin E, as an anti-oxidant, is known to play a critical role in the cellular defense against oxidative stress in mammalian cells. So we investigate the protective effect of VE on SWCNT-induced neurotoxicity of cultured PC12cells.1. Cytotoxicity of single-walled carbon nanotubes on PC 12 cellsDate from MTT and LDH assay demonstrated that SWCNTs decreased PC12 cells viability significantly in a time-and dose-dependent manner, increased the release of LDH and destroyed the membrane integrity of PC 12 cells. Analysis from the cell morphology observation, cell-cycle phase distribution and apoptosis/necrosis revealed that SWCNTs could induce apoptosis in PC12 cells. The apoptosis in SWCNT-induced PC 12 cells was associated with the loss of mitochondrial membrane potential(MMP), the formation of reactive oxygen species(ROS), GSH depletion, supression of the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase(GSH-Px), activation of caspases-8,-3, up-regulation of Bax and down-regulation of Bcl-2 These results suggest that PC 12 cells apoptosis induced by SWCNTs maybe through mitochondria dependent pathway2. Protective effect of VE on SWCNT-induced neurotoxicity of cultured PC 12 cellsThe protective effect of VE on PC 12 cells was analysized when PC 12 cells were pretreated with VE for 1 h prior to exposure to LSWCNT. Date from MTT and LDH nanlysis demonstrated that VE increased cellular viability of PC 12 cells, suppressed SWCNT-induced leakage of LDH. Futher investigation showed that the protective effect of VE against LSWCNT-induced apoptotic cell death was associated with the prevention of the loss of mitochondrial membrane potential, repression of the formation of reactive oxygen, activation the antioxidant enzymatic activities and endogenous antioxidants, down-regulation of the activation of caspase-3 and Bax expression, up-regulation of Bcl-2 expression in PC12 cells. These results suggest that VE may have the ability to counteract the toxicity of SWCNTs by attenuating change of the mitochondrial membrane permeability that is associated with oxidative stress damage.In summary, our results demonstrate that SWCNTs are toxicl to nervous system in some extent, we need to take some protective measures to protect us aginst damage induced by SWCNTs.