内侧前额叶皮层神经元可塑性改变在吗啡奖赏记忆形成中的作用

Effect of mPFC neuron synaptic plasticity changes in the formation of morphine related reward memory

目的 观察吗啡诱导的大鼠内侧前额叶皮质（mPFC）神经元可塑性改变对吗啡奖赏记忆形成的影响.方法 40只SD大鼠分为生理盐水对照组和吗啡组,分别腹腔注射生理盐水（2 ml/kg）和盐酸吗啡（10 mg/kg）,注射后0、2、4、8h断头取脑,Western Blot分析mPFC区Arc/Arg 3.1蛋白变化;另取大鼠60只,分别腹腔注射0、5、10或20 mg/kg吗啡,Western Blot（n=5）分析mPFC区Arc/Arg 3.1蛋白变化;免疫组化法（n=5）检测mPFC区Arc/Arg 3.1阳性细胞数量变化;Golgi-cox改良法（n=5）检测mPFC区神经元棘突数量变化;再取大鼠40只,经8天生理盐水、吗啡交替训练建立条件性位置偏爱（CPP）模型,吗啡模型组大鼠在每次吗啡注射前15 min给予mPFC区注射Arc/Arg 3.1基因的反义寡核苷酸（AS,n=10）及其对照（CS,n=10）,观察其对吗啡CPP评分的影响.结果 与生理盐水对照组相比,10 mg/kg吗啡注射后2 h mPFC内Arc/Arg 3.1蛋白水平、Arc/Arg 3.1阳性细胞数、棘突数量[（1.01±0.04） vs （1.58±0.18）,P＜0.01;（42.80±7.63） vs （74.47±8.02）,P＜0.01;（17.27±5.64） vs （39.47±7.56）,P＜0.01]均显著增加;与对照组相比,5、10或20 mg/kg吗啡注射后2h均可诱导mPFC的Arc/Arg 3.1蛋白水平显著增加,无剂量依赖效应;对于吗啡CPP模型组大鼠,与mPFC区注射CS相比（0.74±0.02）,AS显著降低吗啡CPP的评分（0.51±0.01）,差异具有统计学意义（P＜0.01）.结论 单次吗啡注射可以诱导大鼠mPFC区Arc/Arg 3.1蛋白表达增加并伴有神经元可塑性的增强,增加的Arc/Arg 3.1蛋白介导了吗啡奖赏记忆的形成.

Objective To observe the effect of mPFC neuron synaptic plasticity changes in the formation of morphine related reward memory.Methods 40 SD rats were administered morphine （10 mg/kg,ip） or saline （2 ml/kg,ip）and sacrificed 0,2,4 and 8 h after the treatment.The temporal profile of activity-regulated cytoskeleton-associated protein （Arc/Arg 3.1） expression in medial prefrontal cortex （mPFC） was analyzed.Another 40 rats receiving a single injection of morphine at different doses （0,5,10 or 20 mg/kg）,and rats were sacrificed by decapitation 2 h later.In mPFC,changes of Arc/Arg 3.1 protein was analyzed by Western Blot,Arc/Arg 3.1 positive cells was detected by immunohistochemistry （IHC）,and number of spines were analyzed by Golgi-cox method.In the second experiment,CPP model was established by 5 mg/kg morphine for 8 days.Arc/Arg 3.1 antisense oligodeoxynucleotide （AS） or the control （CS） was microinjected into mPFC 15 minutes before each morphine injection,then CPP score was evaluated.Results Compared with saline groups,Arc/Arg 3.1 protein,Arc/Arg 3.1 positive cells,number of spines （（1.01±0.04） vs （1.58±0.18）,P〈0.01 ; （42.80±7.63） vs （74.47±8.02）,P〈0.01 ;（17.27±5.64） vs （39.47±7.56）,P〈0.01） were significantly increased 2 hours after morphine administration.All three doses of morphine （5,10 and 20 mg/kg） increased Arc/Arg 3.1 protein expression in the mPFC,and there were no dose-dependent effects.In CPP experiments,compared with microinjection of Arc/Arg 3.1 CS （0.74±0.02）,Arc/Arg 3.1 AS microinjection significantly decreased the CPP score （0.51±0.01） in morphine group （P〈0.01）.Conclusion It is enough to increase Arc/Arg 3.1 protein content and synaptic plasticity in mPFC by 10 mg/kg,and the changes implied in formation of morphine relative reward memory.