Effects Of 2650 MHz Electromagnetic Radiation On Emotional Behavior,Learning And Memory Of C57 Mice

Background:With the rapid development of communication technology,mobile communication is stepping into the 5G era,the use of 5G technology has undoubtedly brought great convenience to people,but also caused public concern about the potential harm of 5G mobile phone electromagnetic radiation to human health.After electromagnetic radiation has become the fourth major source of pollution,the International Agency for Research on Cancer(IARC)of the World Health Organization(WHO)has listed electromagnetic radiation carried by mobile phones as possible human carcinogens(category 2B).Therefore,it is necessary to in-depth study of the biological hazards of mobile phone electromagnetic radiation.Studies have shown that the central nervous system is sensitive to electromagnetic radiation,which can cause brain dysfunctions such as emotional behavior and learning and memory,but its specific mechanism is not yet clear.Scholars at home and abroad have carried out a series of studies on this,but the results are often controversial and a unified view has not yet been obtained.In previous studies,the biological hazards of electromagnetic radiation from mobile phones were mainly concentrated between 900 MHz and 1800 MHz,while the potential negative effects of electromagnetic radiation on human health of 2650 MHz is still blank.Therefore,this study selects the 2650 MHz electromagnetic wave in the 5G mobile communication frequency band,and takes male C57BL/6N mice aged 6-8weeks the research object.The specific absorption rate(SAR)is 2W/kg and 4W/kg,respectively.The mice were exposed to the dose of,and the effect of 2650 MHz electromagnetic radiation on the emotional behavior,learning and memory of C57 mice was studied through behavioral evaluation methods,and its mechanism of action was preliminarily explored.Purposes: Explore the effects of 2650 MHz electromagnetic radiation on the emotional behavior,learning and memory of C57 mice,clarify its damage targets and preliminarily clarify its mechanism of action.Chapter 1 Effect of 2650 MHz electromagnetic radiation(2W/kg)on anxiety-like behavior in C57 miceMaterials and Methods: Using electromagnetic reverberation to simulate the electromagnetic radiation environment of 5G mobile phones,male C57 mice were exposed to radiation for 28 days,and the radiation exposure was 4 hours per day.The specific absorption rate of the whole body was 2W/kg.A real-time detection of mouse rectal temperature system under electromagnetic radiation environment was used to detect the change of mouse rectal temperature during the irradiation exposure process.The anxiety like behavior of mice was observed by open field test(OFT)and elevated-plus maze(EPM)on the 21 th and 28 th day of radiation exposure,the depression like behavior of mice was observed by tail suspension test(TST)on the 28 th day of radiation exposure,and the spatial learning and memory ability of mice was observed by Morris water maze(MWM)on the 22nd-27 th day of radiation exposure,separately.Elisa kit was used to detect the level of corticosterone(CORT)in mouse serum,and the morphology and structure of mouse hippocampus and amygdala were observed with light microscope.Western Blot and immunohistochemical methods were used to detect the expression of brain-derived neurotrophic factor(BDNF),aminobutyric acid(GABA)alpha receptor and glucocorticoid receptor(GR)protein in the hippocampus of mice.Results:(1)During the process of radiation exposure,the increase in rectal temperature of mice was less than 1℃,indicating that the thermal effect of electromagnetic radiation under this radiation condition was not significant.(2)2650MHz electromagnetic radiation can induce anxiety-like behaviors in C57 mice but no depression-like behaviors: After 21 d and 28 d of radiation exposure,OFT results showed that the total distance,the distance of the central area and the central area of the Exposure group mice in the open field Exercise time was significantly reduced(P<0.05);the results of EPM showed that the percentage of the number of times the mice in the Exposure group entered the open arm and the percentage of time to enter the open arm in the elevated plus maze were significantly reduced(P<0.05);the results of TST showed that the mice in the Exposure group had no significant immobility in the last 4 minutes change.(3)2650MHz electromagnetic radiation will not cause significant changes in the spatial memory ability of mice: MWM results showed that during the acquisition phase,the escape latency of mice in the Exposure group did not change significantly;and during the probe trial,the Exposure group mice had no significant changes in the number of times they crossed the original platform and the percentage of exploration time in the quadrant where the target platform was located.(4)The results of the Elisa kit showed that the level of CORT in the serum of mice in the Exposure group was significantly increased(P<0.05).(5)2650MHz electromagnetic radiation affected the morphology and structure of amygdala in mice,but had no effect on the structure of hippocampus:the results of light microscopy showed that there was no obvious change in the structure of hippocampus in exposure group,the amygdala neurons showed nuclear pyknosis and deep staining,and the perivascular space increased.(6)Western Blot results showed that the expression of BDNF in the hippocampus of the Exposure group was significantly down-regulated(P<0.05),and there was no significant change in the expression of GABAα;the immunohistochemical results showed that the expression of GR in the hippocampus of the Exposure group was significantly down-regulated(P<0.05).Chapter 2 Effect of 2650 MHz electromagnetic radiation(4W/kg)on learning and memory of C57 miceMaterials and Methods: In this chapter,on the basis of the previous chapter,the specific absorption rate of the whole-body during radiation exposure was increased to4W/kg.A real-time detection of mouse rectal temperature system under electromagnetic radiation environment was used to detect the change of mouse rectal temperature during the irradiation exposure process.MWM was used to observe the spatial learning and memory ability of mice at 22-27 d of radiation exposure,and OFT and EPM were used to observe the anxiety-like behavior of mice at 28 d of radiation exposure.LC-MS was used to detect the levels of amino acids and monoamine neurotransmitters in the serum of mice,and the morphological structure and ultrastructure of the mouse hippocampus were observed by light microscope and transmission electron microscope.Western Blot method was used to detect the expression of BDNF,GABAα,postsynaptic density protein 95(PSD95)and N-methyl-D-aspartic acid(NMDA)receptor protein in mouse hippocampus.Transcriptome sequencing was used to detect the RNA transcription in the hippocampus of mice.Results:(1)The biological effects are mainly non-thermal effects: during the radiation exposure process,the temperature of the mice’s rectal temperature rises less than 1℃,and the thermal effects are not significant.(2)2650MHz electromagnetic radiation does not cause anxiety-like behavior in mice: The results of OFT and EPM show that although the Exposure group has a downward trend in various indicators,there is no significant statistical difference.(3)2650MHz electromagnetic radiation can cause reduced spatial memory in mice: MWM results showed that during the acquisition phase,mice Exposure escape latency was significantly increased(P <0.05);and during the probe trial,the number of times the mice in the Exposure group crossed the original platform and the percentage of exploration time in the quadrant where the target platform was located decreased significantly(P<0.05).(4)After exposure to 2650 MHz electromagnetic radiation,the hippocampal tissue structure of mice: in exposure group,the hippocampal neurons showed nuclear pyknosis and deep staining,increased perivascular space,and neuronal apoptosis in DG area;the number of synapses decreased,the synaptic space blurred,the vesicles decreased,the mitochondria swelled,and the inner spine dissolved and disappeared.(5)Serum neurotransmitters in mice after2650 MHz electromagnetic radiation exposure: Glu levels in the serum of mice in the Exposure group were significantly increased(P<0.05),DA and Gln were significantly reduced(P<0.05 or P<0.01),5-hydroxytryptamine(5-HT)is no significant change in HT and NE levels.(6)Western Blot results showed that the expressions of NR1,NR2 A,NR2B,and GABAα in the hippocampus of the Exposure group were significantly up-regulated(P<0.05 or P<0.01),and the expressions of BDNF and PSD95 were significantly down-regulated(P<0.05).(7)Transcriptome sequencing results showed that there were a total of 751 differential genes in the hippocampus of the Exposure group,of which 277 were significantly up-regulated,474 were significantly down-regulated,and mainly down-regulated.Go(Gene Ontology)function analysis showed that in biological process,it was mainly related to ion transport,membrane potential and learning and memory;in cell composition,it was mainly related to synapse and ion channel complex;in molecular function,it was mainly related to the activity of ion / voltage-gated channel and substrate specific channel.KEGG functional analysis showed that the neuroactive ligand receptor interaction signaling pathway was in the highest agreement with the behavioral results,and there were five genes related to learning and memory and in line with the trend.The expression levels of Gabra2,Gabra3 and Gabra5 were increased in the exposure group,while the expression levels of Drd1 and Drd2 were decreased.Conclusions:(1)With a SAR value of 2W/kg,2650 MHz electromagnetic radiation can induce anxiety-like behaviors in mice and changes in the morphological structure of the amygdala.The possible mechanism is that the down-regulation of GR expression in the hippocampus of mice inhibits the negative feedback regulation function of the HPA axis.As a result,the CORT content released at the end of the HPA axis is significantly increased,which further leads to the occurrence of anxiety behavior.(2)The SAR value is 4W/kg,2650MHz-EMR can cause the learning and memory ability of mice to be damaged,which is manifested by the decline of the mouse’s spatial memory ability,the morphological structure of hippocampus,the changes of ultrastructure and the disorder of serum neurotransmitter metabolism.The decreased spatial learning and memory ability of mice may be related to the neuroexcitatory toxicity mediated by NMDA receptors.In addition,Gabra2,Gabra3,Gabra5,Drd1 and Drd2 may be the key target genes for the decline of learning and memory in mice caused by electromagnetic radiation.