| Electromagnetic radiation(EMR)is a physical effect that exists widely in the world and can be produced naturally or artificially.With the development of science and technology,human beings have produced a variety of types of equipment that generate more and more EMR.A massive dosage and/or long-term artificial EMR exposure can cause reversible or irreversible damage to the human body.The mechanism mainly includes three aspects:thermal effect,non-thermal effect,and accumulation effect.Among them,non-thermal effects are the main mechanism of biological effects.Previous studies on biological effects have focused on the effects of short-or long-term exposure to EMR in low-frequency bands.The EMR field parameter used in the studies is all in the range of 800-2000 MHz.However,modern industrial products,consumer electronics,and military equipment have produced a large number of high-frequency EMR,especially the ultra-high frequency to superhigh frequency band(3-30 GHz)promoted used by the new 5G communication and their biological effects and mechanisms are still largely unclear.Previous animal studies have found that the nervous system is one of the most sensitive targets for EMR.EMR can cause spatial learning and memory impairment through brain oxidative stress,while there are relatively few studies on the effects and possible mechanisms of EMR-induced negative emotions in animals such as anxiety.And negative emotions can significantly affect not only physiological parameters including heart rate,blood pressure,and breath but also brain functions such as learning and memory.Part one: A new five-district method for mouse open field test analysisAnxiety is one type of high alertness and negative emotions without a clear threat,which can cause insomnia,palpitations,shortness of breath,and dizziness,as well as significant learning and cognitive impairments.The open field test(OFT)is a classic behavioral protocol to detect the level of anxiety-like behavior in rodents.It produces a psychological conflict in which rats or mice are afraid of natural enemies and do not dare to be exposed to open areas for a long time while actively seeking new environments for food.The OFT generally determines the level of anxiety-like behavior by the central-district method--the central-district mimics the open area of nature.Therefore,its size is a key parameter.However,different laboratories used the different sizes of the central area,which may lead to abnormal statistical results.In this part of the study,we directly divided the entire open field arena into five square annular areas with the same width from the outside to the inside,named as A/B/C/D/E area.The width of each area was set by the average of the mouse head width.The trajectory of the mouse in the open field was recorded by a video acquisition system and analyzed by Smart 3.0 software.The data of the mouse’s travel distance,number of entries,activity time,and latency into each region,average moving speed,maximum moving speed,and minimum moving speed were analyzed for comparing the level of anxiety-like behavior in different mouse models.We named it the five-district method.We compared the animal model of anxiety induced by chronic inflammatory pain(CFA),the model of animal anxiety induced by drug(FG7142),and the untreated control group by using the central-district method(36% of the total area)and the five-district method,respectively.The results showed that: 1.Both the traditional central-district method and the five-district method can detect increased the level of anxiety-like behavior induced by the chronic inflammatory pain or FG7142 in animals.2.The five-district method provided more details: FG7142 mice had higher levels of anxiety-like behavior than CFA groups: The FG7142 group showed significantly lower changes in the distance and number of entry from the B region than in the WT group,whereas the CFA mice exhibited similar behavioral changes from the C region;mice in the FG7142 group and the CFA group showed inconsistent activity patterns: the FG7142 group had reduced activity time in area E and reduced activity speed in area C,while the CFA group in area C and E Districts showed reduced activity time.The above results show that the central-district method is a more straightforward method in determining whether anxiety-like behavior occurs in animals,and the five-district method can provide more details in comparing the level of anxiety-like behavior and activity patterns of different anxiety models.Part two: The effects of superhigh frequency EMR on the anxiety-like behavior of adult miceIn modern work and life,people are more and more exposed to EMR,especially in the fields of wireless communication,radar,medical treatment,etc.,which use or generate300 MHz ～ 300 GHz ultrahigh frequency and superhigh frequency(SHF)EMR.Several studies have shown that high-frequency EMR causes changes in multiple systems of the body,and the central nervous system is the most sensitive target.However,the development of modern science has increasingly demanded the frequency band of electromagnetic waves,and the use of SHF EMR has gradually increased,but its role in the central system is still unclear.Previous studies on the biological effects of EMR on the central system have mostly focused on learning,memory,and cognition,but lacked attention to the role of emotions.Anxiety is a common negative emotional state in modern life.It can not only cause abnormalities of various physiological parameters of the body but also significantly affect learning,memory and cognitive functions.In this part of work,the brain function and morphological changes underlying anxiety-like behavior that occurred after short-term irradiation were systematically explored by an SHF pulsed electromagnetic field(5 GHz,pulse frequency 10 Hz),combined with the OFT,immunofluorescence.Combining with central-district method and five-district method,we found that a single pulse electromagnetic irradiation for 5 minutes had no significant effect on the anxiety-like behavior of the mice in the OFT since the time and distance of the mice in the central area of the OFT did not change significantly(5 minutes into the open field).However,the mice showed a significant increase the level of anxiety-like behavior in the familiar environment(after entering the open field 5 min)since the mice gradually decreased entries in the central area and increased the speed of each exploration of the central area significantly,which suggested the mice stayed an increased alert-like state.We examined the effect of EMR on neuronal activity by detecting the expression of the immediate early gene c-Fos protein in the whole brain and found that one single SHF EMR can inhibit the neuronal activities of the anterior cingulate cortex,prelimbic cortex,nucleus accumbens,amygdala,and other secondary motor cortex associated with emotional and cognitive related brain regions and motor function.The mice undergo SHF pulsed EMR for a short period(the above parameters are irradiated for 5 min each and 3days for irradiation)showed the up-regulation of phosphorylated extracellular regulated protein kinases,astrocyte activation,and oligodendrocyte proliferation.These changes in molecular and cellular levels may be related to changes in animal mood behavior caused by SHF EMR.Conclusion:(1)When using OFT to detect the level of anxiety-like behavior in mice,the central-district method can determine whether the mice have anxiety-like behavior,while the five-district method can provide more details such as anxiety activity patterns and relative anxiety levels.(2)SHF electromagnetic radiation can induce anxiety-like behavior in mice,accompanied by changes in neuron activity in the emotion and cognition-related brain regions in the brain and changes in astrocytes and oligodendrocytes.The specific dose-response relationship and mechanism need further research. |
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