μ-δ异源二聚体在大鼠吗啡诱导CPP复燃致海马EAAT3表达下调中的作用

摘要

Objective To evaluate the role of μ-δ heterodimer in down-regulation of the expression of excitatory amino acid transporter 3 (EAAT3) in hippocampi caused by reinstatement of morphine-induced conditioned place preference (CPP) in rats.Methods Thirty-two healthy clean-grade male Sprague-Dawley rats,weighing 200-240 g,were assigned into 4 groups (n =8 each) using a random number table method:control group (group C),extinction group (group E),reinstatement group (group R) and reinstatement plus interference plasmid group (group RI).The model of morphine-induced CPP was established,and extinction of CPP was gradually induced by stopping administration.A small dose of morphine 5 mg/kg was intraperitoneally injected again to induce CPP reinstatement,and dwell time around the medicine box was recorded.μ-δ heterodimer interference plasmid 5 μl was injected into the lateral cerebral ventricle after successful establishment of CPP model in group RI.The content of glutamate (Glu) in hippocampi was measured using high-performance liquid chromatography.The EAAT3 expression in hippocampal CA1 and CA3 regions was detected using Western blot.Results Compared with group C,no significant change was found in the dwell time around the medicine box or content of Glu in hippocampi (P＞0.05),and the expression of EAAT3 in hippocampal CA1 and CA3 regions was significantly up-regulated in group E,and the dwell time around the medicine box was significantly prolonged,the content of Glu in hippocampi was increased (P＜0.05),and no significant change was found in the expression of EAAT3 in hippocampal CA1 and CA3 regions in group R (P＞0.05).Compared with group E,the dwell time around the medicine box was significantly prolonged,the content of Glu in hippocampi was increased,and the expression of EAAT3 in hippocampal CA1 and CA3 regions was down-regulated in group R (P＜0.05).Compared with group R,the dwell time around the medicine box was significantly shortened,the content of Glu in hippocampi was decreased,and the expression of EAAT3 in hippocampal CA 1 and CA3 regions was upregulated in group RI (P＜0.05).Conclusion μ-δ heterodimer is involved in down-regulation of EAAT3 expression in the hippocampus caused by reinstatement of morphine-induced CPP in rats.%目的 评价μ-δ异源二聚体在大鼠吗啡诱导条件性位置偏爱(CPP)复燃致海马兴奋性氨基酸转运体3(EAAT3)表达下调中的作用.方法 清洁级健康雄性SD大鼠32只,体重200～240 g,采用随机数字表法,将其分为4组(n=8):对照组(C组)、消退组(E组)、复燃组(R组)和复燃+干扰质粒组(RI组).采用吗啡诱导法建立大鼠CPP模型,停止给药使CPP逐渐消退;再次腹腔注射小剂量吗啡5 mg/kg诱导已消退的CPP复燃,记录伴药箱停留时间.CPP模型建立成功后RI组大鼠侧脑室注射μ-δ异源二聚体干扰质粒5μl.采用高效液相色谱法测定海马谷氨酸含量,采用Western blot法检测海马CA1区和CA3区EAAT3的表达水平.结果 与C组比较,E组伴药箱停留时间和海马谷氨酸含量差异无统计学意义(P＞0.05),海马CA1区和CA3区EAAT3表达上调,R组伴药箱停留时间延长,海马谷氨酸含量升高(P＜0.05),海马CA1和CA3区EAAT3表达差异无统计学意义(P＞0.05);与E组比较,R组伴药箱停留时间延长,海马谷氨酸含量升高,海马CA1区和CA3区EAAT3表达下调(P＜0.05);与R组比较,RI组伴药箱停留时间缩短,海马谷氨酸含量降低,海马CA1区和CA3区EAAT3表达上调(P＜0.05).结论 μ-8异源二聚体参与了大鼠吗啡诱导CPP复燃致海马EAAT3表达下调.