电针对单次长时间应激小鼠恐惧记忆消退及睡眠时相的影响及机制研究

Effects and mechanisms of electroacupuncture on fear extinction and sleep phase in single prolonged stress mice

目的:观察电针对单次长时间应激(SPS)小鼠恐惧记忆消退及睡眠时相的影响,从突触相关蛋白表达探究作用机制。方法:将32只雄性C57BL/6J小鼠随机分成对照组、模型组、电针组和帕罗西汀组,每组8只。采用改良SPS法对模型组、电针组和帕罗西汀组小鼠进行模型制备。造模结束后7 d,电针组小鼠于“百会”和双侧“足三里”行电针干预,选用疏密波,频率3 Hz/15 Hz,电流强度1 mA,干预30 min;帕罗西汀组小鼠予帕罗西汀溶液(2.5 g/L)灌胃(10 mg/kg)。两组均每日干预1次,连续10 d。采用条件性恐惧实验和高架十字迷宫实验观察各组小鼠恐惧记忆消退和焦虑样行为;Medusa大小鼠脑电肌电记录系统检测小鼠睡眠时相;Western blot法检测小鼠海马组织突触后密度蛋白95(PSD95)、活性调节细胞骨架(ARC)、脑源性神经营养因子(BDNF)、谷氨酸受体2A(GluN2A)、谷氨酸受体2B(GluN2B)和谷氨酸受体1(GluA1)的蛋白表达。结果:与对照组比较,模型组小鼠恐惧再暴露3~15 min及恐惧消退0~3 min的凝滞时间延长(P<0.05),恐惧消退指数降低(P<0.05),在高架十字迷宫开放臂的停留时间缩短(P<0.05)。与模型组比较,电针组和帕罗西汀组小鼠恐惧再暴露3~6 min、12~15 min及恐惧消退0~3 min的凝滞时间缩短(P<0.05),恐惧消退指数升高(P<0.05);电针组小鼠在高架十字迷宫开放臂的停留时间延长(P<0.05)。与对照组比较,模型组小鼠觉醒期(Wake)延长(P<0.05),非快速眼动睡眠期(NREM)和总睡眠时间(Sleep)缩短(P<0.05);与模型组比较,电针组和帕罗西汀组小鼠Wake缩短(P<0.05),NREM和Sleep延长(P<0.05)。与对照组比较,模型组小鼠海马组织PSD95、ARC、BDNF、GluN2A和GluA1蛋白表达降低(P<0.05),GluN2B蛋白表达升高(P<0.05);与模型组比较,电针组和帕罗西汀组小鼠海马组织PSD95、ARC、BDNF、GluN2A和GluA1蛋白表达升高(P<0.05),GluN2B蛋白表达降低(P<0.05)。结论:电针“百会”“足三里”可改善SPS小鼠的焦虑样行为、恐惧记忆消退障碍和睡眠时相异常,其机制可能与调控海马突触传递和可塑性蛋白表达有关。

Objective To observe the effects of electroacupuncture(EA)on fear extinction and sleep phase in single prolonged stress(SPS)mice,and explore its mechanism in view of the expression of relevant synaptic proteins.Methods Thirty-two C57BL/6J male mice were randomly divided into a control group,a model group,an EA group and a paroxetine(PRX)group,with 8 mice in each one.Modified SPS method was used to establish PTSD model in the model group,the EA group and the PRX group.Seven days after modeling completion,in the EA group,the intervention was delivered at"Baihui"(GV 20)and bilateral"Zusanli"(ST 36),with disperse-dense wave,3 Hz/15 Hz in frequency and 1 mA in current intensity,for 30 min.In the PRX group,paroxetine solution(2.5 g/L)was administered intragastrically(10 mg/kg).The intervention was given once daily and for consecutive 10 days in the above two groups.The fear conditioning task and the elevated plus-maze test were adopted to evaluate the fear extinction and anxiety of the mice in each group.Using Medusa electroencephalogram(EEG)and electromyography(EMG)recording system from rats and mice,the sleep phase was determined in the mice.With Western blot method adopted,the protein expression of the postsynaptic density protein 95(PSD95),activity-regulated cytoskeleton-associated protein(ARC),brain-derived neurotrophic factor(BDNF),N-methyl-D-aspartic acid receptor 2A(GluN2A),N-methyl-D-aspartic acid receptor 2B(GluN2B)and alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid receptor 1(GluA1)in the hippocampus was detected in the mice.Results Compared with the control group,the freezing time for the fear re-exposure in 3 min to 15 min and the fear extinction in 0 min to 3 min were prolonged(P<0.05),the fear extinction index decreased(P<0.05),and the open arm time(OT)of the elevated plus-maze was shortened(P<0.05)in the model group.When compared with the model group,in the EA group and the PRX group,the freezing time for the fear re-exposure in 3 min to 6 min and 12 min to 15 min,as well as the fear extinction in 0 min to 3 min was shortened(P<0.05),the fear extinction index increased(P<0.05);the OT in elevated plus-maze was longer in the mice of the EA group(P<0.05).The period of wake(Wake)was prolonged(P<0.05),the non-rapid eye movement period(NREM)and the total sleep time(Sleep)were reduced in the model group(P<0.05)in comparison with the control group.Compared with the model group,the Wake was declined(P<0.05),and the NREM and Sleep increased in the EA group and the PRX group(P<0.05).When compared with the control group,the protein expression of PSD95,ARC,BDNF,GluN2A and GluA1 in the hippocampus decreased(P<0.05),and that of GluN2B increased(P<0.05)in the model group.In the EA group and the PRX group,the protein expression of PSD95,ARC,BDNF,GluN2A and GluA1 in the hippocampus was elevated(P<0.05),and that of GluN2B reduced(P<0.05)when compared with the model group.Conclusion Electroacupuncture at"Baihui"(GV 29)and"Zusanli"(ST 36)can ameliorate anxiety-like behavior,fear extinction disorder and abnormal sleep phase in SPS mice,which may be related to the regulation of synaptic transmission and synaptic plasticity expression in the hippocampus.