Abstract: ObjectiveTo investigate the changes of reactive oxygen species(ROS)level and mitochondrial fission-fusion in SH-SY5Y neurons with chronic fluorosis.MethodsNeuroblastoma SH-SY5Y cells were exposed to different concentrations of fluoride(0.04 and 4 mmol/L)in vitro to build cellular model of fluorosis with the exposure time of 6,12,24,and 48 hours,respectively.Mitochondrial morphology and ROS levels of SH-SY5Y stained by mito-tracker RED probe and ROS fluorescence dyes were observed with fluorescence microscope.ResultsCompared with untreatment cells,the numbers of ROS stain positive SY-SY5Y cells(0.4 mmol/L fluoride:15.1±1.4,12.8±2.5,22.6±2.4,30.0±3.1;4 mmol/L fluoride:32.5±1.9,38.1±2.2,69.3±3.1,84.3±3.5)and the numbers of abnormal mitochondria in morphology(0.4 mmol/L fluoride:13±1.4,15±1.7,22.9±1.9,23.7±1.6;4 mmol/L fluoride:15.2±2.3,23.8±1.8,29.1±4,47.7±3.3)were significantly increased after exposure of 6,12,24,and 48 hours(P<0.05).ConclusionTaking excessive amount of fluoride results in high level of oxidative stress and mitochondrial fragmentation,which are dependent on the exposure time and dose of fluoride.