| Objective To establish a model of depression in rats with chronic unpredictable mild stress,and observe the effect of electroacupuncture pretreatment on reducing learning and memory impairment caused by electroconvulsive therapy,and explore the possible mechanism.Methods 108 SFP male SD rats,weighing 180?220g,were selected and divided into 6 groups(n=18)by random number table method:Control group(Control group),Model group(Model group),electroconvulsive therapy group(ECT group),electroacupuncture group(EA),shame electroacupuncture group(NEA group)and AMPK inhibitor group(AI group).The experiment started one week later after the rats were kept for adaptive feeding(counted as the first day of the experiment).The Control group received no experimental intervention treatment,and the remaining five groups were treated with chronic unpredictable mild stress(CUMS)at 9 to 29 days to establish a depression model.After successful modeling,electroconvulsive therapy was performed at 38 to 43 days after intraperitoneal injection of propofol into the ECT group to the AI group.Model group only received propofol anesthesia,no electroconvulsive therapy.The EA group received electroacupuncture at baihui acupoint(GV20)and yintang acupoint(GV29)30min before electroconvulsive therapy.In the NEA group,30min before electroconvulsive therapy,electroacupuncture stimulation was performed at sham acupoints(adjacency to baihui and yintang acupoints for 5 mm).In the AI group,the AMPK inhibitor of Compound C was used by intraperitoneal injection before electroacupuncture.Morris water maze experiment(positioning navigation experiment and space exploration experiment)was conducted at 1,30 and 44 days,respectively.Open field experiment was conducted at7,36 and 50 days.The sugar water preference experiment was conducted at 8,37 and 51 days.And immediately after each sugar water preference test,6 rats in each group were randomly sacrificed,and their brains were placed on ice to be severed.Hippocampal tissues were isolated and the Hematoxylin eosin(HE)staining was used to observe the pathological changes of hippocampal CA1 in rats;The expressions of AMPK and phosphorylated AMPK(p-AMPK)were detected by Western blot;The contents of BDNF,TNF-a,IL-6 and IL-1? in hippocampus of each group were determined by ELISA.Results Morris Water maze test:l)Place navigation test:Compared with the Control group,at day 34,Model group,ECT group,EA group,NEA group and AI group,and at day 48,Model group,ECT group,NEA group and AI group significantly extended the escape latency and swimming path.At day 34,Model group,ECT group,EA group,NEA group,AI group,and at day 48,Model group,ECT group,NEA group,AI group,escape latency and swimming path were significantly prolonged.Compared with day 34,the incubation period and swimming path of the EA group were significantly shortened.Compared with the EA group,the Model group,ECT group,NEA group and AI group significantly extended the escape latency and swimming path at day 48,with statistically significant differences(P<0.05);2)Space exploration test:Compared with Control group,at day 35,Model group,ECT group,EA group,NEA group and AI group,and at day 49,Model group,ECT group,NEA group and AI group significantly reduced the number of crossing the platform.Compared with day 6,at day 35,Model group,ECT group,EA group,NEA group and AI group,and at day 49,Model group,ECT group,NEA group and AI group,the number of crossing the platform was significantly reduced.Compared with the 35th day,the number of crossing the platform in the EA group increased significantly.Compared with the EA group,the number of crossing the platform was significantly reduced in the Model group,ECT group,NEA group and AI group at day 49,and the difference was statistically significant(P<0.05).Open field test:Compared with the Control group,the Model group,the ECT group,the EA group,the NEA group and the AI group at day 36,and the Model group at day 50,both the horizontal and vertical motion scores decreased.Compared with the Model group,the ECT group,the EA group,the NEA group and the AI group,the horizontal and vertical motor scores were significantly reduced at day 36 and the Model group at day 50.At day 36,the scores of horizontal movement and vertical movement were significantly increased in the ECT group,EA group,NEA group and AI group.At day 50,the horizontal and vertical motor scores of the Control group and the EA group were significantly increased compared with the ECT group.Compared with Model group,horizontal and vertical motion scores of Control group,ECT group,EA group and NEA group were significantly increased(P<0.05).Sucrose preference test:Compared with the Control group,the Model group,the ECT group,the EA group,the NEA group and the AI group reduced the sugar water consumption and sugar water preference rate at day 37 and the Model group at day 51.Compared with the Model group,the ECT group,the EA group,the NEA group and the AI group,the sugar water consumption and the sugar water preference rate all decreased at day 37 and the Model group at day 51.Compared with day 37,the sugar water consumption and sugar water preference rate increased in the ECT group,EA group,NEA group and AI group at day 51.At day 51,compared with the Model group,the sugar water consumption and sugar water preference rate of the Control group,ECT group,EA group,NEA group and AI group were all increased,while compared with the ECT group,the sugar water consumption and sugar water preference rate of the Control group and EA group were both increased,with statistically significant differences(P<0.05).Pathological changes:At day 8,the hippocampal CA1 area of each group of rats were normal in shape,complete in structure,uniform and dense,with clear layers.Closely packed cells,assumes the circular or elliptic,abundant cytoplasm,nucleolus is clear,at day 37,the Model group,ECT,EA group,NEA group,the AI group are different degrees of neurological damage change,tissue edema,color becomes shallow,disordered arrangement of cells,nucleus pycnosis,lack nucleoli,the shape is irregular,some cells are vacuolated.At day 51,compared to the rest of the four groups,at EA group,the hippocampus neuron cell number increased obviously,closely packed,cell assumes the circular or elliptic,clear nucleoli,brain damage degree reduce significantly.Compared with other groups,at ECT group,severe nerve damage change,tissue edema,color becomes shallow,disordered arrangement of cells,the nucleus pycnosis,lack nucleoli,irregular form.Western blot:Compared with the Control group,the Model group,ECT group,EA group,NEA group and AI group at day 37?the Model group,ECT group,NEA group and AI group at day 51,the expressions of AMPK and p-AMPK were significantly down-regulated;Compared to day 8,Model group,ECT group,EA group,NEA group and AI group at day 37,Model group,ECT group,NEA group and AI group at day 51,the expressions of AMPK and p-AMPK were significantly down-regulated;Compared to day 37,the expressions of AMPK and p-AMPK were significantly up-regulated in the EA group at day 51;Compared with the EA group,the expressions of AMPK and p-AMPK in Model group,ECT group,NEA group and AI group down-regulated significantly at day 51(P<0.05).ELISA:Compared with the Control group,the Model group,the ECT group,the EA group,the NEA group,and the AI group at day 37,and the Model group at day 51 showed significant decreases in BDNF,TNF-?,IL-6,and IL-1? concentrations.At day 8,the concentrations of BDNF,TNF-a,IL-6,and IL-1? in Model group were significantly decreased in Model group,ECT group,EA group,NEA group,and AI group at day 37,and Model group at day 51.The concentrations of BDNF,TNF-a,IL-6 and IL-1? in the ECT group,EA group,NEA group and AI group were significantly higher than those at day 37.Compared with the Model group,the concentrations of BDNF,TNF-a,IL-6,and IL-1? in the Control group,the ECT group,the EA group,the NEA groupj and the AI group were significantly increased at day 51.Compared with the ECT group,the concentrations of BDNF,TNF-a,IL-6,and IL-1? in the Control group and the EA group were significantly increased at day 51,with statistically significant differences(P<0.05).Conclusion Chronic unpredictable mild stress can lead to depression-like behavior changes in rats,which are mainly manifested as decreased exploration of new environment and adaptive ability,anhedonia,and electroconvulsive therapy can improve their symptoms.However,the rats showed varying degrees of learning and memory impairment after electroconvulsive therapy.Compared with simple propofol anesthesia,electroacupuncture pretreatment can enhance the antidepressant effect of electroconvulsive therapy and effectively improve the reduced learning and memory function after electroconvulsive therapy.The mechanism may promote the release of BDNF in the hippocampus by activating AMPK signaling pathway,reduce the release of inflammatory mediators TNF-a,IL-6 and IL-1? in the hippocampus,and thereby improve the learning and memory decline induced by electroconvulsive therapy in the depression model rats. |
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