Effect Of ELF-EMF Induced ROS Accumulation On Neuronal Oxidative Injury,Apoptosis And MiRNA Regulating By LSPCs

Extremely low frequency electromagnetic field(ELF-EMF)is an electromagnetic field of frequency 0-300 Hz,and is mostly produced by manmade sources and all kinds of household appliances.Central nervous system is highly sensitive to ELF-EMF,easily lead to oxidative stress,active oxygen free radicals(reactive oxygen,species,ROS)overproduction,thereby causing neurodegenerative disease occurrence and development.However,recent studies are still concentrated in the ELF-EMF risk assessment and physical protection,little attention to the prevention effect and the mechanism of diet adjustment to ELF-EMF.Therefore,on the basis of previous study,we investigated the role of ROS accumulation during the process of ELF-EMF(50Hz,8mT 90min)exposure-induced oxidative stress injury and apoptosis in hippocampal neurons,the effect of ROS accumulation on microRNA,and the prevention and regulation effect of LSPC(procyanidins from lotus seedpod,LSPCs).The main results are as follows:1.ELF-EMF exposure-induced oxidative injury of hippocampal neurons mediated by ROS accumulation and the preventive effect of LSPCsTo investigate the prevention effect of LSPCs and role of ROS accumulation in the process of oxidative stress injury of hippocampal neurons induced by ELF-EMF,inhibitor N-acetyl-L-cysteine(N-acetyl-L-cystein,NAC)was used as the control.The results showed that the main source of ROS accumulation in hippocampal neurons induced by ELF-EMF was mitochondrial H2O2 and O·2-.Compared with the control,the activities of antioxidant enzyme decreased,but the content of lipid hydroperoxide malondialdehyde(MDA)increased;In addition,exposure to ELF-EMF significantly reduced the expression of SOD-1,SOD-2 and GSH-Px protein(P<0.01);However,LSPCs effectively removed the excessive ROS in neurons,increased the activities of antioxidant enzyme.These results indicated that LSPCs has a preventive effect on ELF-EMF induced oxidative stress mediated by ROS.2.ELF-EMF exposure-induced hippocampal neuron apoptosis mediated by ROS accumulation and the preventive effect of LSPCsTo investigate the preventive effect of LSPCs and the role of ROS accumulation in the process of hippocampal neuron apoptosis induced by ELF-EMF,the ROS inhibitor NAC and the caspase inhibitor Z-VAD-FMK were used for the control.The results showed that,compared with control,exposure to ELF-EMF induced ROS accumulation in hippocampal neuron,caused cell apoptosis in morphology.The potential of mitochondrial membrane and the concentration of intracellular free calcium ions were respectively 0.71 and 1.55 times of the control.The cell cycle was arrested at S phase.Cytochrome C protein expression was 1.64 times of control.The expression of anti-poptosis protein Bcl-xl decreased 57.14%,the ratio of Bcl-2/Bax decreased 71.14%,and caspase-3 and-9 were activated.All these indexes exhibited significant differences compared with control(P<0.01).However,respectively pretreatment with LSPCs,NAC and Z-VAD-FMK,could improve the above indexes.These findings indicated that ROS is involved in the whole process of neuronal apoptosis,and LSPCs has a preventive effect on ELF-EMF induced neuronal apoptosis mediated by ROS3.Effects of ELF-EMF on miRNA expression in hippocampal neurons and the regulation of LSPCsCompared with control,7 miRNAs were up-regulated while 3 miRNAs were down-regulated in the ELF-EMF group(P <0.05).Compared with ELF-EMF group,pretreatment with LSPCs,18 miRNAs were up-regulated,and 16 miRNAs were down-regulated.Among them,the expression levels of rno-miR-6215,rno-miR-338-5p,rno-miR-451-5p and rno-miR-132-3p in hippocampal neurons were significantly up-regulated after exposure to ELF-EMF(Fold change>1.5).Pretreatment with LSPCs effectively decreased the expression of rno-miR-338-5p and rno-miR-451-5p(Fold change <0.66),while the expression of rno-miR-6215 and rno-miR-132-3p had no significant difference compared with ELF-EMF group.Exposure to ELF-EMF significantly down-regulated the expression of rno-miR-153-3p and rno-miR-449a-5p(Fold change <0.66),however,both of them were up-regulated by LSPCs(Fold change>1.5).GO and KEGG Pathway analysis showed that the target genes regulated by ELF-EMF-induced differentially expressedmiRNAs were mainly associated with metabolic pathway,neurotrophic factor signal transduction pathway,calcium homeostasis,and MAPK signaling pathway.LSPCs could regulate the expression of miRNAs by the above signals and pathways.