| Background Sleep is a spontaneous and reversible resting state of the higher vertebrate cycle,it appears to be a temporary interruption of the body's responsiveness to external stimuli and consciousness.Sleep disorders,such as insomnia,can lead to a range of serious and life-threatening diseases.Human understanding of the nature of sleep benefits from the development and application of EEG(electroencephalograph,EEG)recording technology.The electrophysiological effects of EEG brain activity can be amplifier in the form of a wavy stripes by electronic instruments.Through the observation and analysis of the EEG waveform can get plenty of sleep related information for insomnia related studies,and provide strong scientific evidence for the research on insomnia.Objective To explore the effects of EA-ACR(Electrostimulation at Auricular Concha Region,EA-ACR)on insomnia rats by Sleep EEG Power spectral.Methods Rats were divided into control group,model group,EA-ACR group and EA-ETA(Electrostimulation at Ear-tip Area,EA-ETA)group(n=6 in each group)in the experiment.A week after the adaptive feeding of rats,the electrode placement operation was performed.In the implanted electrode operation,the miniature homemade electrode socket were fixed to the skull of all the rats for recording the sleep EEG,and the electrode sockets were fixed to the skull with dental cement.The electrode sockets with the wires were connected to the Neural Signal processor when the electrical record is recording.After operation procedures,rats were allowed to recover in the following one week.And then the PCPA(Para-chlorophenylalanine,PCPA)was given to rats by intraperitoneal injection for the model group,EA-ACR group and EA-ETA group to establish the insomnia model.The rats of EA-ACR and EA-ETA group under inhaled anesthesia were treated once daily via an electroacupuncture apparatus for seven consecutive days.The electrical stimulus parameter is a frequency of 2/15 Hz(2 and 15 Hz,switched every second)and an intensity of 2mA.The sleep EEG were recorded for all groups after the treatment daily for seven consecutive days.After the acquisition of EEG signal,the power spectrum analysis method based on the fast fourier transform was applied to calculate the power spectrum distribution changes in delta,theta,alpha and beta frequency bands of the rats before and after the interventions.Results The results of power spectrum analysis are as follows.(1)The Percentage changes of frequency band in control group and model group:Due to the small differences of the percentages of the power spectrum within the blank group(P>0.05),so values of the delta,theta,alpha and beta for the seven consecutive days were be averaged to compare with the model group.The EEG signals were mainly in the form of delta and theta frequency band in control group(delta 80%,theta 14%,alpha 6%,beta 2.3%)when the rats were quiet which consistent with the physiological performance of rats.After modeling,compared with the control group,the proportion of delta frequency band in model rats significantly declined(delta:P<0.05),theta,alpha and beta frequency band obviously raised(theta:P<0.05,alpha:P<0.05,beta:P<0.05)(delta 53.6%,theta 30.7%,alpha 10.4%,beta 5%).It was demonstrated that the EEG power of the model rats shifted to the right,the rats slept less and the insomnia model were built successfully.(2)The Percentage changes of delta frequency band:compared with the model group,the proportion of the delta frequency band escalated and reached its peak in the EA-ACR group at the third day(increase rate:the first day:6.5%,the second day:15.2%,the third day:21%)and the differences between the EA-ACR group and the model group gradually increased(P<0.05).The value of the first day was 74%and the third day was 91.8%in the control group.However,the increasing proportion did not continue but decreased gradually(increase rate:the fourth day:15.7%,the fifth day:10.9%),there was a statistical difference(P<0.05)as compared with the model group.And then gradually increased again(increase rate:the sixth day:13.9%)and tends to be stable(the seventh day:15.1%).It indicated that the anti-insomnia effect did not continue after three days,but a slight decline and then showed a slight recovery and stability to the end.Compared with the model group,although the proportion of the delta frequency band in EA-ETA group were increased at the first two days(increase rate:the first day:2.6%and the second day:4.6%),the changes were not significant(P>0.05).And the value even got lower than it in the model group on third day(reduction rate:-3.7%)to the fifth day(reduction rate:-9.4%),which indicated that the insomnia rats were still in a state of excitement and EA-ETA had no positive effects.From the sixth day to seventh day,the decreasing proportion had a slightly increased but there was no difference from the model group(increase rate:the sixth day:2.6%and the seventh day:2.7%)(P>0.05).(3)The Percentage changes of theta frequency band:compared with the model group,the proportion of the theta frequency band decreased gradually in the EA-ACR group which were approximate the value in the control group at the first three days(reduction rate:the first day:l%,the second day:-10.4%and the third day:15.1%,the fourth day:15.9%,P<0.05).And the decreasing proportion had a slight step-up(reduction rate:the fifth day:7.5%,the sixth day:7.52%)and then decreased gradually(reduction rate:the seventh day:8.2%)(P>0.05).Compared with the model group,the proportion of the theta frequency band had a faintly decline in the EA-ETA group at the first two days(reduction rate:the first day:1.9%and the second day:1%),but this changes had no significant differences from the model group(P>0.05).On the third day,the proportion continued to decrease(reduction rate:9.2%).The decreased proportion then went up instead which even approximate to the value in the model group(P>0.05)on the fourth day(over the model group 5%)which meant that the EA-ETA could not improve the insomnia.On the contrary,rats in the EA-ETA group were more excited or vigilant in comparison with the model group(P>0.05).Although there was another slack from the fifth day to seventh day(reduction rate:the fifth day:1.4%,the sixth day:1.2%,the seventh day:1.3%)compared to the model group,but there was no statistical significance(P>0.05).(4)The Percentage changes of alpha frequency band:compared with the model group,the proportion of the alpha frequency band showed a decreasing trend(reduction rate:the first day:0.8%,the second day:2.9%,the third day:5.6%)in the EA-ACR group and then slightly raised to be stable(reduction rate:the fourth day&fifth day:2.6%and the sixth day:2.4%,the seventh day:3.5%),there was no statistical difference(P>0.05).Compared with the model group,the proportion of the alpha frequency band in the EA-ETA group had a slow and slight fluctuation from the first day to the seventh day(reduction rate:the first day:1.6%,the second day:0%,the third day:2.7%,the fourth day:0.6%,the fifth day:1%,the sixth day:-0.1%,the seventh day:0.4%),but still approximate to the value in the model group(P>0.05).(5)The Percentage changes of beta frequency band:compared with the model group,the proportion of the beta frequency band in EA-ACR group showed a slight twists and turns that a gradual decline and then a downward(reduction rate:the first day:-1.2%,the second day:1.46%,the third day:2.9%,the fourth day:1.5%,the fifth day:1.5%,the sixth day:2.3%,the seventh day:1.8%)from the first day to the seventh day,there was a significant different to compare with model group(P<0.05).From the first day to the fifth day,the proportion of the beta frequency band in EA-ETA group also showed a trend of slight twists and turns(reduction rate:the first day:1.7%,the second day:1.8%,the third day:0.6%,the fourth day:0.95%,the fifth day:0.1%).On the sixth day to the seventh day,the values even higher than them in the model group.(the values of exceeding the model group:the sixth day:0.35%,the seventh day:0.6%).There was no statistical difference(P>0.05).Conclusion EA-ACR can significantly increase the proportion of the delta frequency band,significantly reduce the proportion of the theta frequency band on the first to fourth day,significantly reduce the proportion of the beta frequency band.It suggests that the synchronous oscillation of the brain neuron is likely to stimulate by EA-ACR,which makes the EEG signals of the delta and beta power spectrum distribution characteristics changed,reflects the excitatory state of the cerebral cortex was inhibited in the rats with insomnia. |
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