The In Vitro Study Of Toxic Effects Induced By Titanium Dioxide Nanoparticles On The Central Nervous System

Owing to their excellent physiochemical property,titanium dioxide nanoparticles(TNPs)are widely used in plenty of fields(such as life field,industry,medical domain),which increases the risk of getting exposed to TNPs for people.Recently,several in vivo and in vitro studies have confirmed the potential toxicity of TNPs on the central nervous system.The molecular mechanisms underlying neurotoxicity of TNPs include oxidative stress,inflammation,apoptosis,dysregulated signaling pathway,impaired cytoskeleton.Recent reports have revealed that necroptosis and DNA methylation are involved in nanotoxicity.However,whether necroptosis and DNA methylation are implicated in neurotoxicity of TNPs are still unknown.Therefore,we measure conducted several experiments,such as inductive coupling plasma mass spectrometry(ICP-MS),cell viability determined by cell counting kit(CCK8),lactate dehydrogenase leakage(LDH),RT-qPCR,enzyme-linked immunosorbent assay(ELISA),to preliminarily study the relationship between necroptosis/DNA methylation and neurotoxicity of TNPs on neuronal cell lines(SH-SY5Y and PC12 cells).First chapter.The cytotoxicity on SH-SY5Y cells induced by TNPs with or without Nec-1 pretreatment.Physicochemical property of TNPs was determined.SH-SY5Y cells were exposed to different concentrations of TNPs for 24 h to assess whether necroptosis is involved in neurotoxicity of TNPs.Results showed that the cell viability reduced significantly,with increased level of LDH.Meanwhile,the number of necrosis,determined by flow cytometer was enhanced.While pretreating SH-SY5Y cell with Nec-1 before exposure abrogated those harmful effects induced by TNPs.Second chapter.Inflammatory response of SH-SY5Y cells induced by TNPs with or without Nec-1 pretreatment.SH-SY5Y cells were exposed to different concentrations of TNPs for 24 h to determine the relationship between necroptosis and inflammationis.TNPs exposure promoted the secretion of TNF-?,IL-1?,and IL-6(determined by RT-qPCR and Elisa)when SH-SY5Y cell were exposed to them for 24 h,which was abrogated by pretreating SH-SY5Y cells with Nec-1 before exposure.Third chapter.The effect of TNPs on global DNA methylation of PC12 cells.PC 12 cells were exposed to TNPs for 24 h to assess whether global DNA methylation is involved in neurotoxicity of TNPs.After PC 12 cells were incubated with TNPs for 24 h,Ti contents in cells increased by ICP-MS.The cell viability determined by CCK8 was slightly reduced and the level of LDH leakage was slightly up-regulated after exposure.However,these sub-lethal concentrations of TNPs could reduce the DNMT activity and the global DNA methylation significantly.Taken together,both necroptosis and global DNA methylation are involved in neurotoxicity of TNPs.