| Objective:In recent years,due to the frequent occurrence of environmental pollution,various kinds of foodborne lead pollution have emerged,which has had a serious impact on people's healthy life.Through the food chain and use natural ingredients of food to raise the body's antioxidant ability and ability to cope with oxidative stress level,has become a new direction of the current functional food research.Folic acid is a vitamin that is rich in fruits and vegetables.It has a strong antioxidant capacity and can promote neural stem cells.So we built a PC12 cell model,using lead as an inducer for cell damage,and folic acid as a cell protectant.Study on the damage mechanism of lead on nerve cells,and the effect of folate on the proliferation and apoptosis of nerve cells with lead exposure,and the antioxidant capacity and the effect of A?40 and A?42 in the culture medium.Methods: under the condition of stable cell growth,PC12 cells were exposed to 24 h with lead free medium and 10?mol/L lead acetate culture solution.After that,all the culture solution was sucked out,and the folic acid medium with 0mg/L,0.5mg/L,5mg/L and 50mg/L continued to function.The PC12 cells were collected after 24 h,48h and 72 h respectively,and the proliferation or inhibition of cells were detected by MTT method.The cell protein was extracted and the activity of SOD,MDA and GSH-PX in each group was detected.The expression of apoptotic protein caspase-3 protein was studied by immunofluorescence.The changes of A?40 and A? 42 in cell culture fluid were detected by ELISA.The result: according to the MTT,the lead exposure can inhibit the growth of the PC12 cells,and as the time increases,the inhibition rate gets higher and higher.Folic acid is significantly promote the proliferation of PC12 cell(P < 0.05),with the increase of time(72 h)cell proliferation rate is declining,but the total number of cells is increased,and in certain dose range,folic acid concentration,the greater the PC12 cell proliferation rate and cell count showed a trend of rising.Folic acid had a significant effect on PC12 cells in lead exposure group(P < 0.05),and with the increase of folic acid dose,the cell inhibition rate of folic acid in lead exposure group decreased gradually,and the number of cells increased continuously. According to the results of each oxidative index,lead can significantly increase the content of MDA and SOD activity in cells,and significantly reduce the vitality of gsh-px(P < 0.05).Folate of 50 m L/L significantly increased intracellular MDA content and gsh-px activity(P < 0.05).Compared with the lead exposure group,50 m L/L folic acid significantly reduced MDA content in the lead exposure group and significantly increased the activity of SOD and GSH-PX(P < 0.05).Immunofluorescence results showed a significant increase in caspase-3 protein in lead exposure group.Compared with the control group,the expression of caspase-3 was also significantly increased in folic acid group.The results of ELSA showed that,compared with the control group,there was a significant decrease in the amount of A?40 in the cell culture medium of lead exposure group(P < 0.05),and that in the medium of folate 50mg/L group,A?40 was increased.But there was no significant difference(P < 0.05);There was no significant difference in the content of the cell culture medium A?40 and the control group,folic acid 50mg/L group and lead exposure group(P > 0.05).However,there was no significant difference in A?42 in cell culture medium of each group(P > 0.05).Conclusion: Lead can increase lipid peroxidation and oxidative stress in cells,and induce the expression of caspase-3 protein to inhibit cell growth and promote apoptosis.Folic acid can protect the PC12 cells that are damaged after lead exposure.It may reduce the content of MDA by up-regulating SOD,GSH-PX activity,and thereby inhibit or delay the expression of caspase-3 protein to protect the damaged cells.Further studies are needed to confirm whether high doses of folic acid can produce side effects. |
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