| Research purposes:Kunming mice were selected as experimental subjects for experiments,and the experimental animals were subjected to acute and chronic stress respectively to establish acute and chronic stress depression models.Behavioral tests were performed on mice in the stress group and control mice,to explore the changes in behavior and learning and memory ability of experimental animals before and after stress.Changes of the expression of angiopoietin-2(ANG-2)and PI3 K in CA1,CA3 and DG areas of the hippocampus and in the prefrontal cortex.Observe whether the morphology and structure of various nerve cells in different areas of the brain change.Explore the role of angiopoietin ANG-2 in the process of nerve injury repair.Research method:Kunming mice were used as experimental animals,and they were raised in a laboratory environment for a week to acclimate to the laboratory environment.Chronic stress animal model were established by seven stressors were fasting,hathpace,lighting through the night,water deprivation,clod water swimming,oblique cage,foot shock for 4 weeks respectively.An acute stress model of animal were established by foot shock.The method of acute stress in mice is to use electric current stimulation,and specifically,a single electric current was used to stimulate the soles of the mice under acute stress.The behavioral changes of mice are detected by behavioral experiments,the despair of mice are tested by tail suspension experiments,the anxiety behaviors of mice are detected by open field experiments,and the data of each behavior index is recorded.Morris water maze experiment detects before and after stress whether the learning ability of mice is significantly improved or decreased.After HE staining,observe the changes in the morphological structure of neuronal cells in the brain under a microscope.The main brain areas observed are the prefrontal cortex and hippocampus,because these two areas be closely related to the occurrence of depression and the ability of learning and memory.The hippocampus was mainly observed the areas are CA1,CA3,and DG areas.Whether the cell morphology,structure,and arrangement are changed.Immunohistochemical experiments were used to detect the PFC in the prefrontal cortex and the hippocampus CA1,CA3,DG area ANG-2and PI3 K in the experimental animal brain expression.Research result:Compared with the control group,the weight change of mice after chronic stimulus stress showed no significant difference.The experimental data showed that chronic stress had little effect on the weight of mice.In the tail suspension experiment,compared with the control group,there was a significant difference in the first immobility time of the mice receiving chronic stimulus stress,and there was no significant change in the cumulative immobility time within six minutes.After the mice were subjected to the open field experiment,through the data processing of the observation indicators,there was a significant difference in the number of standing uprights of the mice after chronic stress compared with the blank control group,and the number of horizontal grids decreased and there was a significant difference.The mice in the excited group stayed longer in the central grid of the open field than in the control group,and the number of stool particles and the number of modifications did not change significantly.In the Morris water maze experiment.(1)The escape latency(i.e.,the time from entry to the target platform quadrant)and the total distance traveled in each cycle of the mice were observed and recorded during the place navigation test.Comparison within the group,the escape latency were shortened in each group mice,and comparisons between groups showed that the escape period of mice after chronic stress was significantly longer than that of the control group,and the total distance of each cycle of the two groups of mice decreased and there was a significant difference.(2)After the space probe experiment of each group of mice,the residence time in the target quadrant was longer than that in the other quadrants.In the HE staining experiment,the morphology and structure of each cell in the forebrain of the control group mice were clear and the structure was complete,and the cell morphology and structure in the hippocampus were also the same.The morphological structure of the cells in the brain area of the experimental group of mice after chronic stress changed.Immunohistochemical staining experiments on the slices,observe and take pictures under a microscope,process the pictures after taking pictures,and analyze the data.Compared with the control group,the mice after chronic stress stimulation have protein expression in each brain area.Differently,the expression of angiopoietin ANG-2 in the cerebral cortex PFC decreased significantly.Similarly,the expression of ANG-2 in the CA1 area of the hippocampus decreased significantly,the CA3 area also showed the same expression,and the DG area also had significant changes.Compared with mice that did not receive stress stimulation,the expression of ANG-2 in each brain area of the stress group were significantly reduced.The expression level of PI3 K were detected,it was found that the expression of PI3 K in the prefrontal cortex was significantly reduced,and the DG area in the hippocampus showed significant differences.The expression of mice in the chronic stress group were significantly reduced,while the expression of other parts of the hippocampus did not change significantly.After the mice received acute stress,they were compared with a control group mice that did not receive stimulation.By analyzing the data of each experiment,the excitability of the mice was significantly improved after receiving the acute stimulus in tail suspension test.Mice stopped struggling for longer time than control group mice,i.e.,the first immobility time was significantly longer.The cumulative immobility time of stress group mice were significantly shorter compared with the control group mice.There were significant differences in the number of standing up and the number of horizontal grids in the open field test after the acute stress.In Morris water maze experiment,compared with the control group mice,the escape latency,the total distance in each cycle,and the residence time in each quadrant in the stress group mice were three behavioral parameters.It indicated that the learning and memory ability of mice would be enhanced and the excitability would be improved after acute stress.The results of immunohistochemical experiments showed that the expression of ANG-2 and PI3 K in the prefrontal cortex and hippocampus of mice in the acute stress group was significantly increased compared with the control group mice.The results of HE staining showed that there was no change in the morphology of neuronal cells in the two groups of mice.Conclusion:1.After the mice receive long-term chronic stimulation,they will have a stress response,and the changes after chronic stress can be manifested in behavior and physiology.2.In terms of behavior,mice receiving chronic stress have high levels of anxiety and despair,and show reduced mobility in the open field experiment.In the water maze experiment,it can be seen that the spatial learning and memory ability is damaged to a certain extent.3.In the histological experiment,the expression of ANG-2 and PI3 K in each brain area of mice in the chronic stress group decreased,and some areas showed significant differences.The expression of ANG-2 and PI3 K increased significantly after acute stress.4.Acute and chronic stress caused changes in the behavior and learning and memory ability of the mouse depression model.These changes are related to the expression of ANG-2 and PI3 K in the mouse brain. |
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