Role Of ERS In Neural Stem Cells Apoptosis Induced By Fluoride

The nuerotoxicity of fluorine has caused wide public concern, but its direct toxicity to the neural stem cells (NSCs) has still not been reported. Using C17.2NSCs and primary embryonic rat cortical NSCs as in vitro models, we determined the effects of sodium fluoride (NaF) on the cell viability, oxidative stress, apoptosis, and the expression levels of endoplasmic reticulum stress (ERS) markers. Our study will explore the role of ERS in NaF induced NSCs apoptosis, and provide a theoretical basis for the studies of neurotoxic effects of fluorine.Part1Role of ERS in C17.2neural stem cells apoptosis induced by fluorideObjective:To explore the effects of fluoride on cell viability rate, oxidative stress, apoptosis, the expression levels of Caspase-3and ERS markers GRP78, IRE1and CHOP in C17.2NSCs.Methods:The cell viability rate was measured by methylthiazolyltetrazolium (MTT) assay after the NSCs were incubated with10,30,60and80mg/L NaF for24h in vitro. The activity of intracellular superoxide dismutase (SOD), the contents of intracellular malondialdehyde (MDA), the level of intracellar ROS, the apoptosis, the expression levels of Caspase-3and ERS markers GRP78, IRE1and CHOP were detected after the NSCs were incubated with10,30and60mg/L NaF for24h in vitro.Results:Compared with control group, the cell viability rate of30,60and80mg/L groups significantly decreased(P<0.05) and the viability rate in80mg/L NaF-treated group was less than50%. Compared to control group, the ROS level of all the NaF-treated groups were significantly high(P<0.05), while the activity of SOD in fluoride-treated groups were remarkably low (P<0.05), the MDA contents and the percentages of apoptosis in30and60mg/L NaF-treated groups were notably high (P<0.05), meanwhile the expression level of Caspase-3in60mg/L NaF-treated group was significantly low (P<0.05). The expression levels of IRE1and CHOP in30and60mg/L groups were remarkably elevated (P<0.05).Conclusion:NaF could inhibit growth of C17.2NSCs, decrease the cell viability rate, induce oxidative stress and, trigger apoptosis that could be mediated by UPR.Part2Effect of fluoride on cell viability in primary embryonic rat cortical neural stem cellsObjective:To explore the effect of fluoride on cell viability in primary embryonic rat cortical NSCs and to determine the fluoride-exposed doses.Methods:The primary embryonic rat cortical NSCs were cultured with DMEM/F12and identified using the NSCs marker Nestin. The cell viability rate was measured by MTT assay after the NSCs were incubated with40,80,120and200mg/L NaF for24h in vitro.Results:Nestin was expressed in the primary cultured cells. Compared with the control, the viability rates of the NaF-treated groups were significantly decreased(P<0.05).Conclusion:NaF could inhibit growth of primary embryonic rat cortical NSCs.