Effect Of Acupuncture On ERK1 / 2 - CREB - BDNF Signaling Pathway In Prefrontal Cortex Of Depression Model Rats

Purpose:Depression is a kind of mood disorder syndrome, which is seriously harm to the physical and mental health of people, and have a high rate of disability and mortality. It brings great economic and mental burden to the family and society. The pathogenesis of depression is complex, and it is closely related to stress,chronic stress can lead to neuronal cell damage and apoptosis in the related brain areas, especially in the hippocampus and frontal lobe. Therefore, it is one of the key targets for the treatment of depression to repair the damage of the neurons in the brain areas and promote their regeneration.The extracellular regulated protein kinase (ERK1/2) pathway of mitogen activated protein kinase (MAPK) pathway is closely related to the proliferation and growth of cells. It is mainly to promote the brain-derived neurotrophic factor (BDNF) secretion, which can exert anti-injury and promote growth in nerve cells.Preliminary studies of our group confirmed that acupuncture can activate the ERK1/2 signaling pathway in the hippocampus of chronic stress depression model rats, and promote the regeneration of neurons in the hippocampus, which can play a role in anti-depression. Because the frontal lobe is the senior center of the emotion regulation, and has the multi-level coordination function to the cognition, the feeling and the movement, which plays an important role in the pathogenesis of depression. However, there is little research about whether acupuncture can activate the ERK1/2 signaling pathway in the frontal lobe to exert the anti-depressant effect.Therefore, this study specifically inhibited the ERK1/2 signaling pathway, and observed the changes of the protein expression levels of p-ERK1/2, p-CREB and BDNF of ERK1/2 signal pathway in the frontal lobe of chronic stress depression model rats. To verify the validation of the research, and continue to explore and improve the anti-depression mechanism of acupuncture, which involved the activate of ERK/CREB/BDNF MEK/signaling pathway.Methods:1. Experimental groupsSixty-eight male Sprague-Dawley rats (180±10g) were randomly divided into eight groups (eight rats in each group):the control group, the model group, the model+acupuncture (Acu) group, the model+fluoxetine (Flu) group, the model+DMSO group, the model+PD98059 group, the Model+Acu+PD group, the Model+Flu+PD group.2. Modeling methodsCombine solitary with chronic unpredictability mild stress (CUMS) method to establish depression model. CUMS method including:food deprivation (24 h), water deprivation (24 h), bound (2 h), the oscillation (30 min); tail clip (3 min), wet bedding (24 h), the night light (12 h). In the process of experiment, each type of stress stimulation is conducted 3 times in alternate way in 21 days. A week before the building, model+DMSO group, model+PD group, acupuncture+PD group and the flu+PD group receive lateral ventricle casing embedment surgery.3. Intervention methodsAcupuncture treatment of selected "Bai hui" and "Yin tang", use twirling stimulation methods at the depth of 0.5-1 cm, retaining needle 20 min once a day; Fluoxetine is mixed with distilled water at 1.8 mg/kg of suspension liquid, with 10 ml/kg lavage. Reduce additional stimulus when the above process is operated.4. Process methodsDo not give any stimulus to control group, which are group housed. Other groups are feed separately receiving 21 days CUMS stimulation. At the same time, the acupuncture group receive acupuncture treatment 30 min before modeling on each day. Flu group receive fluoxetine lavage 30 min before stimulated on each day. Model+DMSO group receive 10ul/ Id DMSO lateral ventricle injection 1h before stimulated. Model+PD group receive lOul/ Id block inhibitor PD98059 diluent lateral ventricle injection 1 h before stimulated. Acupuncture+PD group, flu+PD group receive 10ul/Id block inhibitor PD98059 diluent lateral ventricle injection 1h before stimulated, and then are separately given acupuncture treatment and fluoxetine lavage 30 min before stimulated.5. Detection index and methodsUsing open-field test, body weight and sucrose intake test to evaluate the behavior change of depression model rats. Using Western blot method to detect protein expression levels of ERK, p-ERK, p-CREB, BDNF in the prefrontal cortex of rats.Results:1. Behavioral changeBefore building:there is no statistical significance in Sucrose intake, open-field test between groups of rats (all P>0.05). There is no significant difference in body quality between not operated groups of rats (blank group, model group, acupuncture group, the fluoxetine group) (all P>0.05);There is no significant difference in body quality between Surgical groups of rats (model+DMSO group, model+PD group, acupuncture+PD group, fluoxetine+PD group) (all P>0.05).After model building:(1) Compared with the blank group, the body quality, sucrose intake, open-field test of model group rats all declined significantly (P<001); (2)Compared with model group, the body quality, sucrose intake, open-field test of acupuncture group and drug group rats all increased significantly (P<0.01); The sucrose intake, open-field test of model+DMSO group rats had no significant difference (P>0.05); The sucrose intake, open-field test of model+PD group rats both decreased (P<0.05); (3)Compared with acupuncture group, the sucrose intake, open-field test of acupuncture+PD group rats both decreased (P<0.01) and the sucrose intake, open-field test of fluoxetine group rats had no significant difference (P>0.05); (4)Compared with fluoxetine group, the sucrose intake, open-field test of fluoxetine+PD group also decreased (P<001); (5)Compared with model+ PD group, the sucrose intake of fluoxetine+PD group increased, but had no significant difference with acupuncture+PD group (P>0.05); the open-field test of acupuncture+PD group and fluoxetine+PD group increased significantly.2. The key indicator’s change of ERK1/2 signaling pathway in frontal lobeThere is no difference of ERK1/2 protein expression between groups of rats (all P>0.05). (1)Compared with the blank group, the protein level of p-ERK1/2, p-CREB, BDNF in frontal lobe of model group rats decreased significantly (P<0.01); (2)Compared with the model group, the protein level of p-ERK1/2, p-CREB in frontal lobe of acupuncture group and the fluoxetine group rats were significantly higher (all P<0.01). The BDNF expression in frontal lobe of acupuncture group increased (P<0.05), which of fluoxetine group increased more significantly (P<0.01). Compared with the model group, the protein level of p-ERK1/2, p-CREB and BDNF in frontal lobe of the model+DMSO group, model+PD group rats had no significant difference (P>0.05); (3)Compared with acupuncture group, the protein level of p-ERK1/2, p-CREB in frontal lobe of acupuncture+PD rats were significantly lower (all P<0.01), but the expression of BDNF had no significant difference (P> 0.05), while the protein level of p-ERK1/2, p-CREB and BDNF in frontal lobe of fluoxetine group had significant difference (all P>0.05); (4)Compared with fluoxetine group, the p-ERK1/2 protein expression in frontal lobe of fluoxetine+PD group rats reduced (P<0.05), the p-CREB expression of which reduced significantly (P<0.01), while the expression of BDNF had no significant difference (P>0.05); (5)Compared with the model+PD group, acupuncture+PD group and the fluoxetine+PD group had no significant difference in p-ERK1/2 and BDNF protein expression (P>0.05), while about p-CREB protein expression, acupuncture+PD group increased (P<0.05), fluoxetine+PD group increased more significantly (P<0.01).Conclusions: 1. Combining solitary keep with chronic stress can significantly inhibit activation of ERK1/2 signaling pathways, leading to the decrease of the body quality, exploring behavior and senstivity to reward mechanism。2. Acupuncture intervention can dramatically improve the depression behavior of model rats, which may be by raising phosphorylation level of ERK1/2 protein, activating the vigor of CREB protein and expanding the final effect of the expression of BDNF protein.3. Acupuncture also may be directly affect the protein expression of BDNF and produce positive feedback effect of ERK signaling pathway.4. The antidepressive effect of acupuncture may be made more by ERK1/2 signaling pathways.