Electroacupuncture on hippocampal CREB/BDNF/TrkB in depressive rats effects of signaling pathways

ZHAO Ting-ting, ZHU Tao, ZHANG Jie, ZHAI Ling, SUN Jia-zi

1.Shanxi University of Traditional Chinese Medicine, Jinzhong 030619, China;

2.Shanxi Provincial Hospital of Traditional Chinese Medicine, Taiyuan 030012, China

ABSTRACT Objective: To investigate the effect of electroacupuncture on CREB/BDNF/TrkB signaling pathway in hippocampus of depressed rats.Methods: The depression rat model was established by chronic unpredictable stress (CUMS) combined with solitary rearing.The rats were randomly divided into blank group, model group, electroacupuncture group and fluoxetine group, with 10 rats in each group.In the electroacupuncture group, 'Baihui','Shenting', 'Hegu' and 'Taichong' were selected.Acupuncture was performed 1 h before modeling every day, and the needles were retained for 20 min, once a day for 21 d.Fluoxetine group: Fluoxetine (10 mg/kg, 1 mg/mL) was intragastrically administered 1 h before modeling for 21 d.The changes of body weight, the number of standing and the distance of movement in open field test, the immobility time of forced swimming test were observed.The contents of 5-HT, DA and NE in serum were detected by ELISA.The expression of BDNF, CREB and TrkB in hippocampus was detected by Western blot.The expression of BDNF and CREB mRNA in hippocampus was detected by real-time fluorescence quantitative PCR.Results:After modeling intervention: Compared with the blank group, the body weight, the number of standing, the distance of movement, the content of serum 5-HT, DA and NE, the expression of BDNF, CREB and TrkB in the hippocampus of the model group were significantly decreased(all P＜0.01), and the immobility time was significantly increased (P＜0.01).Compared with the model group, the body weight, the number of standing, the distance of movement, the content of 5-HT, DA and NE in serum, the expression of BDNF, CREB and TrkB in hippocampus were significantly increased (all P＜0.05), and the immobility time was significantly decreased(P＜0.05) in the EA group and fluoxetine group.There was no significant difference between the electroacupuncture group and the fluoxetine group (P＞0.05).Conclusion: EA can significantly improve the symptoms of depression in rats, and its mechanism may be related to the regulation of BDNF/TrkB/ CREB signaling pathway-related proteins in hippocampus,increase the content of monoamine neurotransmitters 5-HT, NE and DA, resulting in antidepressant effect.

Keywords:

Electroacupuncture

Depression

BDNF

CREB

TrkB

1.Introduction

Depression refers to an affective disorder characterized by sustained low mood, accompanied by symptoms such as emotional depression, lack of pleasure, cognitive impairment, and even emotional disorders such as self-harm, suicidal thoughts, or behaviors[1].In recent years, with the increase of social pressure,the incidence and prevalence of depression have been on the rise[2,3].Currently, fluoxetine-based Western medicine is mainly used in clinical treatment of depression, although it is effective in rapid relief, it is prone to relapse and has significant side effects[4].Electroacupuncture is an improved acupuncture therapy combined with electrical stimulation, which has been used more frequently in neurological diseases (including stroke, depression, insomnia, and stress-related illnesses) than conventional acupuncture treatment,and has been shown to be significantly effective in clinical treatment of depression[5,6].At the same time, clinical research has also shown that electroacupuncture stimulation of related acupoints is effective in treating depression[7].Previous studies by our research team have shown that acupuncture can improve the symptoms of depression and improve the quality of life of patients[8].In view of this, on the basis of previous studies, this study further observed the effect of electroacupuncture on CREB / BDNF / TrkB signaling pathway in hippocampus of depressed rats to explore its mechanism.

2.Materials and methods

2.1 Animals and grouping

Fifty male SD rats with SPF grade, weighing (200±20) g, were purchased from Beijing Sibeifu Biotechnology Co., Ltd., with license number SCXK (Beijing) 2019-0010.They were housed in the animal facility of Shanxi University of Traditional Chinese Medicine, at a temperature of 20～23℃, relative humidity of 60～70%, and a 12-hour light/dark cycle.After one week of adaptation, the rats underwent an open field test, and 40 rats with normal behavior scores between 30 and 120 were selected.They were then randomly divided into four groups: blank group,model group, electroacupuncture group, and fluoxetine group,with ten rats in each group, using a random number table method.The experimental protocol was approved by the Animal Ethics Committee of Shanxi Acupuncture Research Institute, with approval number: LSK 2020-003.

2.2 Main reagents and instruments

High-speed centrifuge (Model: SH01D, Shanghai ZhiXin Experimental Instrument Technology Co., Ltd.), vortex mixer(Model: XH-C, Jiangsu Datang Medical Equipment Co., Ltd.),microplate thermostat shaker (Model: TS300, Hangzhou Ruicheng Instrument Co., Ltd.), electrophoresis instrument (Model: DYY-7C,Beijing Liuyi), fully automated chemiluminescence imaging analysis system (Model: Tanon5200, Shanghai Tianneng), tissue homogenizer(Model: SCIENTZ-24, Ningbo Xinzhong), PCR instrument (Model:Gene Amplifier TC-XP, Hangzhou Borui Technology), fluorescent quantitative PCR instrument (Model: LightCycler? 96, Hangzhou Borui Technology), rat open field experiment system (Model: OFT-200A, Chengdu Taimeng Software Co., Ltd.).

Pentobarbital (Batch No.820219, Shanghai No.2 Pharmaceutical Factory), Sucrose (Batch No.S818096-500g, McKlin Company),Fluoxetine Hydrochloride (Batch No.F844356, McKlin Company),NE ELISA Kit (Batch No.RA20557, Bioswamp), DA ELISA Kit(Batch No.RA20050, Bioswamp), 5-HT ELISA Kit (Batch No.RA20031, Bioswamp), BCA Protein Quantification Kit (Catalogue No.AR0146, BOSTER), Electrophoresis Buffer (Catalogue No.AR1146, BOSTER), Transfer Buffer (Catalogue No.AR1151,BOSTER), BDNF Antibody (Catalogue No.PB9075, BOSTER),CREB Antibody (Catalogue No.PB1027, BOSTER), TRKB Antibody (Catalogue No.13129-1-AP, Wuhan Proteintech),GAPDH Antibody (Catalogue No.BM1623, BOSTER), HRP-Goat Anti-Rabbit Antibody (Catalogue No.BA1054, Bioss), HRP-Goat Anti-Mouse Antibody (Catalogue No.BA1050, Bioss), TRIzol?Reagent (Model No.15596026, Invitrogen), Chloroform (Model No.10006818, Shanghai Pharmaceutical Group), Isopropanol (Model No.80109218, Shanghai Pharmaceutical Group).

2.3 Model preparation

Reference[9] was improved and used the Chronic Unpredictable Mild Stress (CUMS) method to model the rats.Except for the control group, rats were housed alone, and received one of the following stimuli randomly each day for 21 consecutive days: 24-hour lightdark reversal, 24 h food deprivation, 24 h water deprivation, tail clip(2cm from tail tip, 3 min), 24 h humid environment, 24 hflickering,24 h cage without bedding, 24 h 45° tilt cage, 10 times olfactory stimulation, and 3 h 85dB noise stimulation.Each day, a stimulus was selected randomly using a random number table, and the same stimulus was not used for two consecutive days.The modeling group showed decreased body weight, lower levels of exploration in the open field test, lower vertical scores, and longer immobility time in the forced swim test, indicating successful modeling and suggesting the rats were in a state of depression with weight loss, reduced activity, and hopeless behavior.

2.4 Intervention methods

All treatment groups received relevant treatment 1 hour before stress, 7 days a week for a total of 3 weeks.The specific procedures were as follows:Blank group: Normal feeding, group feeding,and no intervention;Model group: Adapted feeding for 1 week,modeling for 3 weeks, and no treatment;Electro-acupuncture group:According to “Experimental Acupuncture”, the rat acupoint map was used to select “Baihui”, “Shenting”, “Hegu”, and “Taichong”.Acupuncture was performed 1 hour before modeling each day,using a 0.25×25 mm needle, with 15° horizontally inserted at“Baihui”and “Shenting”, and 45° obliquely inserted at “Hegu”and “Taichong”.The electrodes were connected to the same side of“Hegu”and “Taichong”.The frequency was 2 Hz, and the intensity was 1-1.2 mA, with slight limb tremors.The needles were retained for 20 minutes, once a day for 21 consecutive days.Fluoxetine group:Fluoxetine (10 mg/kg, 1 mg/mL) was orally administered 1 h before modeling each day for 21 consecutive days.

2.5 Index observation and detection

2.5.1 Body mass observation Observations and records of body weight for each rat were taken and statistically analyzed prior to (day 1) and after (day 21) modeling intervention.This index can reflect the appetite of depressed rats, and reduced food intake similar to symptoms of anorexia and emaciation in depression.

2.5.2 Open field test

Conduct an open field experiment before and after modeling intervention.Place rats in the center square of the open field box and record their horizontal movement (total distance traveled) and vertical movement (forelimb suspension or wall climbing frequency)within 5 minutes.After each test, clean the bottom of the open field box with a 75% medical ethanol solution.This reflects the rats’exploratory behavior, environmental adaptability, and anxiety and depression emotions.The total distance of horizontal movement and forelimb suspension frequency of rats are analyzed by Chengdu Taimee Software Co., Ltd.

2.5.3 Forced swimming test

Place rats into a transparent cylindrical container with a height of 50 cm, a diameter of 20 cm, a water depth of approximately 35 cm,and a water temperature of 25±2 ℃, and let them swim for 5 min.After a 1 min adaptation period, observe the swimming state of the rats and record the immobilitytime of the rats within 5 min (with the standard of “immobility”being defined as occasional slight movements of the limbs to keep the head above water for breathing),with the glass tanks separated by partitions.After each animal was tested, water was changed, and the animal was dried.This was used to evaluate whether the depression model animals exhibited behavior of despair.

After observing the above indicators, 1% pentobarbital (4 mL/kg)was injected intraperitoneally for anesthesia, and 5 mL of blood was collected from the abdominal aorta.The rat was then decapitated under sterile conditions and the hippocampal tissue was harvested and reserved for later use 1.5.4 Elisa detectionof the content of 5-HT,DA, and NE in rat serum.Centrifuge the rat blood of each group at 3 000 r/min for 10 minutes and collect the supernatant.Follow the instructions of the ELISA kit and after the enzyme-linked immunosorbent assay (ELISA) reader reads the absorbance value,calculate the serum contents of 5-HT,DA, and NE according to the standard curve.

2.5.5 The protein expression of BDNF, CREB and TrkB in hippocampus of rats was detected by Western-Blot.

Extract hippocampus tissue protein and measure its protein concentration using the BCA method.Then perform electrophoresis,transfer to a membrane, block the membrane, and add primary antibodies (BDNF antibody 1:1 000, CREB antibody 1:1 000, TrkB antibody 1:1 000).Refrigerate at 4 ℃ overnight, and then wash the membrane with P-BST the next day, add goat anti-rabbit IgG (1:1 000) and incubate at room temperature for 2 h.After washing the membrane with P-BST, place the blotting membrane on an imaging analyzer for automatic imaging, and analyze the grayscale value of the protein bands using ImageJ software.

2.5.6 The expression of BDNF and CREB mRNA in hippocampus was detected by real-time fluorescence quantitative PCR.

The total RNA of hippocampus was extracted by Trizol kit, and its concentration and purity were detected.Primer design and synthesis were completed by Shanghai Bioengineering Co., Ltd.The total mRNA was used as a template and reverse transcribed into cDNA for PCR amplification.The reaction was performed in a 20 μL system : 1μL qPCR primer, 1ul cDNA product, 10 μL SYBR Green qPCRMaster Mix (2x).Amplification conditions : 95℃-15s, 58 ℃ -20s, 72 ℃ -20s, a total of 40 cycles, the dissolution curve of 60 ℃ -95 ℃, every 15 s temperature 0.3 ℃ Through the measured threshold ( Ct ) and the standard curve, the relative initial concentration of the sample to be tested was obtained.The relative initial concentration of the target gene and the corresponding relative initial copy number of GAPDH were divided to obtain the relative expression of BDNF and CREB.The primer sequence is shown in Table 1.

Tab 1 Primer sequence of PCR

2.6 statistical method

SPSS 25.0 statistical software was used for analysis and processing.The measurement data were expressed as mean ± standard deviation(±s).All data were in accordance with normal distribution.Oneway analysis of variance was used for comparison between multiple groups, and homogeneity of variance test was performed.If the variance was homogeneous, LSD method was used for comparison between the two groups.If the variance is uneven, the Tamhane 's T test is used, and P ＜ 0.05 is considered statistically significant.

3.Result

3.1 Comparison of body weight of rats in each group

Compared with the body weight of the same group before and after modeling intervention, the differences in each group were statistically significant (P ＜ 0.01).After modeling intervention :compared with the blank group, the body weight of the model group was significantly reduced (P ＜ 0.01) ; compared with the model group, the body weight of the electroacupuncture group and the fluoxetine group increased significantly (P＜0.05).There was no significant difference between the electroacupuncture group and the fluoxetine group ( P ＞ 0.05 ).See Table 2.

Tab 2 Body weight of rats in each group(n=10, ±s)

Tab 2 Body weight of rats in each group(n=10, ±s)

Note : Comparison with the same group before and after modeling intervention,1)P＜0.01;compared with the blank group,2)P＜0.01;compared with model group,3)P＞0.05;Comparison with fluoxetine group,4)P＞0.05.

Groups Before modeling intervention After modeling intervention blank group 252.40±5.89 358.30±12.131)model set 253.40±5.75 291.70±8.292)electroacupuncture group 254.40±4.79 334.80±6.833)4)Fluoxetine group 251.10±6.61 324.50±10.273)F 0.592 83.102 P 0.624 0.000

3.2 Open field experiment of rats in each group

There was no significant difference in standing times and movement distance between the same group before and after modeling intervention.(P＞0.05),The differences in other groups were statistically significant.(P＜0.01).After modeling intervention: compared with the blank group, the number of standing and the distance of movement in the model group were significantly reduced.(P＜0.01);Compared with the model group, the standing times and movement distance of the electroacupuncture group and fluoxetine group increased significantly.(P＜0.05);There was no significant difference between the electroacupuncture group and the fluoxetine group.(P＞ 0.05).See Tables 3,4.

Tab 3 Number of standing in open field of rats in each group (n=10, ±s)

Tab 3 Number of standing in open field of rats in each group (n=10, ±s)

Note : Comparison with the same group before and after modeling intervention,1)P＞0.05;compared with the blank group,2)P＜0.01;compared with model group,3)P＜0.05;Comparison with fluoxetine group,4)P＞0.05.

Groups Before modeling intervention After modeling intervention blank group 15.80±2.39 15.70±2.501)model set 15.90±2.88 5.20±1.322)electroacupuncture group 14.90±2.92 11.20±1.753)4)Fluoxetine group 16.80±3.05 9.40±1.583)F 0.757 55.975 P 0.526 0.000

Tab 4 Open field movement distance of rats in each group (n=10, ±s)

Tab 4 Open field movement distance of rats in each group (n=10, ±s)

Note : Comparison with the same group before and after modeling intervention,1)P＞0.05;compared with the blank group,2)P＜0.01;compared with model group,3)P＜0.05;Comparison with fluoxetine group,4)P＞0.05.

Groups Before modeling intervention After modeling intervention blank group 5501.10±301.69 5473.50±296.291)model set 5550.40±315.70 2817.20±248.282)electroacupuncture group 5637.10±240.61 4178.60±258.123)4)Fluoxetine group 5473.50±296.29 3920.20±157.763)F 0.613 197.585 P 0.611 0.000

3.3 Comparison of immobility time of forced swimming in rats of each group

Compared with the immobility time before and after modeling intervention in the same group, there was no significant difference in the blank group.(P＞0.05),The differences in other groups were statistically significant.(P＜0.01).After modeling intervention :compared with the blank group, the immobility time of the model group increased significantly.(P＜0.01);Compared with the model group, the immobility time of the electroacupuncture group and the fluoxetine group was significantly reduced.(P＜0.05);There was no significant difference between the electroacupuncture group and the fluoxetine group.(P＞0.05).See Table 5.

Tab 5 Immobility time of rats in each group(n=10, ±s)

Tab 5 Immobility time of rats in each group(n=10, ±s)

Note : Comparison with the same group before and after modeling intervention,1)P＞0.05;compared with the blank group,2)P＜0.01;compared with model group,3)P＜0.05;Comparison with fluoxetine group,4)P＞0.05.

Groups Before modeling intervention After modeling intervention blank group 55.52±3.12 59.69±4.861)model set 56.87±1.86 104.59±4.832)electroacupuncture group 55.10±4.35 79.16±4.763)4)Fluoxetine group 56.72±3.78 85.16±3.593)F 0.658 155.903 P 0.583 0.000

3.4 The contents of 5-HT, DA and NE in serum of rats in each group were compared.

After modeling intervention : compared with the blank group,the content of 5-HT, DA and NE in the model group decreased significantly.(P＜0.01);Compared with the model group, the contents of 5-HT, DA and NE in the electroacupuncture group and the fluoxetine group were significantly increased.(P＜0.05);There was no significant difference between the electroacupuncture group and the fluoxetine group.(P＞0.05).See Table 6.

3.5 Comparison of protein expression of BDNF, CREB and TrkB in hippocampus of rats in each group.

After modeling intervention : compared with the blank group, the protein expression of BDNF, CREB and TrkB in the hippocampus of the model group was significantly decreased.(P＜0.01);Compared with the model group, the protein expression of BDNF, CREB and TrkB in the hippocampus of the electroacupuncture group and the fluoxetine group was significantly increased.(P＜0.05);There was no significant difference between the electroacupuncture group and the fluoxetine group.(P＞0.05).See Figure 1, Table 7.

Tab 6 Changes of serum 5-HT、DA and NE contents of rats in each group (n=10,±s)

Tab 6 Changes of serum 5-HT、DA and NE contents of rats in each group (n=10,±s)

Note : Compared with the blank group,1)P＜0.01;compared with model group,2)P＜0.05;Comparison with fluoxetine group,3)P＞0.05.

Groups 5-HT NE DA blank group 176.37±19.65 97.42±17.31 97.65±17.46 model set 133.91±17.48 50.87±16.31 43.46±19.431)electroacupuncture group 169.79±18.01 77.27±16.66 75.57±16.742)3)Fluoxetine group 155.19±13.29 72.60±15.29 69.32±19.222)F 11.873 13.560 14.932 P 0.000 0.000 0.000

Fig 1 Protein bands of BDNF,CREB and TrkB in hippocampus

Tab 7 Expression of BDNF,CREB and TrkB in hippocampus of rats in each group(n=10, ±s)

Tab 7 Expression of BDNF,CREB and TrkB in hippocampus of rats in each group(n=10, ±s)

Note : Compared with the blank group,1)P＜0.01;compared with model group,2)P＜0.05;Comparison with fluoxetine group,3)P＞0.05.

Groups BDNF CREB TrkB blank group 0.82±0.09 0.78±0.04 0.84±0.17 model set 0.24±0.021) 0.25±0.041) 0.24±0.121)electroacupuncture group 0.61±0.082)3) 0.59±0.032)3) 0.62±0.152)3)Fluoxetine group 0.55±0.092) 0.52±0.102) 0.57±0.052)F 28.503 40.506 14.442 P 0.000 0.000 0.001

3.5 The expression of BDNF and CREB mRNA in hippocampus of rats in each group was compared.

After modeling intervention : compared with the blank group, the expression of BDNF and CREB mRNA in the hippocampus of the model group was significantly decreased.(P＜0.01);Compared with the model group, the expression of BDNF and CREB mRNA in the hippocampus of the electroacupuncture group and the fluoxetine group was significantly increased.(P＜0.05);There was no significant difference between the electroacupuncture group and the fluoxetine group.(P＞0.05).See Table 8.

Tab 8 Expression of BDNF and CREBmRNA in hippocampus of rats in each group(n=10, ±s)

Tab 8 Expression of BDNF and CREBmRNA in hippocampus of rats in each group(n=10, ±s)

Note : Compared with the blank group,1)P＜0.01;compared with model group,2)P＜0.05;Comparison with fluoxetine group,3)P＞0.05.

Groups BDNF mRNA CREB mRNA blank group 1.02±0.26 1.01±0.16 model set 0.24±0.101) 0.22±0.031)electroacupuncture group 0.78±0.042)3) 0.65±0.062)3)Fluoxetine group 0.66±0.052) 0.56±0.072)F 15.136 36.944 P 0.001 0.000

4.Discuss

Depression belongs to the category of ' depression syndrome 'in traditional Chinese medicine[10]." Miscellaneous disease origin Rhinoceros candle ·the source of depression " cloud : " the depression, dirty gas disease, which was originally in the deep thinking, but also dirty gas weak, so the six depression of the disease." " Spiritual Pivot ·Original God " says : ' It is so scary that thinking hurts God, and God hurts fear.Therefore, traditional Chinese medicine believes that the formation of depression is mainly due to the failure of the liver to disperse and the failure of the spleen to transport, resulting in the loss of the original spirit and the dysfunction of the organs.The disease is mainly located in the brain, and the heart, liver, spleen, kidney and other organs[11].The selection of acupoints is one of the important factors affecting the treatment of depression.In this experiment, Baihui, Shenting,Hegu and Taichong were selected as acupoints.Baihui and Shenting were the intersection points of Governor Vessel and Foot-Taiyang meridians, which were the places where meridians and qi converge,and had the effects of regulating primordial spirit, tranquilizing mind and relieving depression.Hegu and Taichong have the effect of soothing the liver and relieving depression and calming the liver and suppressing yang.The ' acupuncture point name solution ' puts forward : ' Hegu and Taichong are famous for the four passes, so that they can be greatly opened.' Open the four passes to regulate the qi movement of the body, so as to achieve the smooth qi movement and the qi stagnation.

At present, fluoxetine, as a selective serotonin reuptake inhibitor, is the most commonly used antidepressant in clinical practice.It can significantly improve the mood of patients with depression, but longterm use can easily cause agitation and induce hypomania in some individuals.Symptoms[12,13].In recent years, acupuncture therapy, as a traditional Chinese medicine characteristic therapy, is often used to supplement and replace depression.Acupuncture therapy combined with Baihui, Shenting, Hegu, Taichong and other acupoints can regulate all external activities of the human body and the purpose of viscera function.It is the so-called ' Dumaitong, Zhujingtong,Naoqiaocong '.The results showed that electroacupuncture at Baihui,Shenting, Hegu and Taichong could significantly improve the body weight of depressive rats, increase the distance of autonomous activities and the number of standing in the open field, reduce the immobility time of forced swimming and improve depressive behavior.

In the brain nervous system, monoamine neurotransmitters ( 5-HT), dopamine ( DA ) and norepinephrine ( NE ) control a variety of physiological, behavioral and endocrine functions[14].According to relevant literature, depression is caused by a decline in the function of related monoamine neurotransmitters, such as 5-HT, NE and DA[15].Previous studies have also shown that the lack of monoamine neurotransmitters such as 5-HT, NE and DA can aggravate depressive behavior and can be used as a diagnostic indicator of depression[16].As one of the main monoamine neurotransmitters, 5-HT can regulate a variety of behavioral and physiological functions, such as emotion,fear, aggression, appetite, sleep, memory and reproduction[17] ; nE can affect human pleasure sensation and stress response function[18];dA is related to human mental state[19].Through the detection of neurotransmitters 5-HT, NE and DA in the brain, it was found that electroacupuncture could significantly increase their levels, improve oxidative stress, regulate the disorder of HPA axis function, and improve the depressive symptoms of rats.

As a key signaling pathway for hippocampal nerve regeneration,BDNF / TrkB / CREB can promote the growth of nerve cells,participate in the remodeling of synapses, and is also a key node for the brain to regulate emotional behavior[20,21].As a neurotrophic factor, BDNF regulates a wide range of cellular functions in the nervous system, including dendritic and axonal growth, neuronal survival, synaptic transmission and LTP in the hippocampus.It plays a crucial role in the development of the nervous system and promotes neuronal differentiation, cell survival and neurogenesis[22].TrkB is a high affinity receptor for BDNF.When BDNF promotes the survival of related nerve cells by activating TrkB, up-regulates the expression of synaptic-related proteins, promotes neurite outgrowth, regulates neuronal differentiation and growth, repairs nerve damage, and exerts antidepressant effects[23].CREB is an important regulatory factor in the upstream of BDNF signaling pathway, and the expression of BDNF is also regulated by CREB[24].CREB is phosphorylated by BDNF at the transcriptional regulatory site, and CREB can regulate its gene transcription through a calcium-dependent mechanism,thereby providing feedback to BDNF[25].In addition, CREB can also form a positive feedback loop with BDNF / TrkB signal.TrkB signal can activate CREB by phosphorylation, and phosphorylated CREB will then activate BDNF to enhance TrkB signal, thereby enhancing the body 's antioxidant capacity and reducing the apoptosis rate of nerve cells, thus exerting antidepressant effect[26].Experimental studies have shown that electroacupuncture can significantly increase the expression of BDNF, CREB and TrkB, enhance the activity of CREB / BDNF / TrkB signaling pathway, reduce the level of oxidative stress and improve the symptoms of depression in rats.In summary, electroacupuncture at Baihui, Shenting, Hegu and Taichong can significantly improve the depression-like behavior of rats, including increasing body weight, increasing autonomous activity in the open field, and reducing swimming immobility time.The mechanism may be related to the regulation of BDNF / TrkB /CREB signaling pathway-related proteins, increase the content of monoamine neurotransmitters 5-HT, NE and DA, thereby producing antidepressant effects.

Author contribution description:

Zhao Tingting:Experimental design and operation, data collation and statistical analysis, thesis writing ; zhu Tao, Zhai Ling, Sun Jiazi: experimental operation assistant ; zhang Jie : Research guidance,thesis revision, financial support.

All authors declare that there is no conflict of interest.