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

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.

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

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.