运动对大鼠纹状体DA含量及AMPA受体亚基表达可塑性的影响

Exercise-induced Plasticity of Striatal Dopamine Contents and AMPA Receptor Subunits in Rats

观察中等运动强度对纹状体内多巴胺(dopamine,DA)含量及ɑ-氨基-3-羟基-5-甲基-4-异恶唑丙酸(AMPA)受体表达的影响,探求运动促进脑可塑性的机制。方法:清洁级SD大鼠62只分为4组:安静对照组(Sham)、运动7 d组(Ex7)、运动14 d组(Ex14)和运动28 d组(Ex28)。适应性饲养1周后开始进行跑台训练,运动方案为11 m/min,30 min/day。采用Panlab系统观察运动对大鼠自主活动能力的影响;采用高效液相色谱(high-performance liquid chromatography,HPLC)观察纹状体DA含量,采用免疫组织化学和Western-blotting观察运动对纹状体AMPA受体的GluR1和GluR2/3亚基表达水平的影响。结果:采用Smart 3.0软件分析大鼠自主活动能力结果发现,长期(第14和28 d)运动训练可以显著增加大鼠自主活动能力(P<0.01);HPLC结果发现Ex28组较Sham组DA含量显著升高(P<0.01),而Ex14和Ex7组较Sham组无显著改善(P>0.05);免疫组织化学检测的结果发现,长期(第14和28 d)运动干预可以显著增加GluR1和GluR2/3亚基的表达(14 d:P<0.05,28 d:P<0.01),短期运动(第7 d)较Sham组无显著改善(P>0.05)。结论:跑台运动可以显著提高大鼠的自主活动能力及纹状体DA含量和GluR1和GluR2/3亚基的表达水平,对纹状体神经递质含量和受体表达产生可塑性影响。推测:DA含量提升和AMPA受体亚基表达的改变是运动提升大鼠运动表现的重要基础之一,可能是运动改善学习记忆、认知和行为的可塑性机制之一。

Objective： To study the plasticity mechanism of moderate exercise on the brain structure, we investigated the expression of the AMPA receptor subunits（GluR1 and GluR2/3） and dopamine contents in striatum. Methods：Sixty-two adult male Sprague Dawley rats were randomly divided into four groups according to duration of treadmill exercise, namely 7 days（Ex7）, 14 days（Ex14）, 28 days（Ex28） and Sham groups. All the rats in the exercise group were forced to run on a motorized treadmill（11 m/min for 30 min each day）. As behavioral evaluations, autonomic movement were recorded by the Panlab system. After exercise, the brains were subjected to immunohisochemistry and immunoblotting to analyze changes of GluR1 and GluR2/3. Animals in high-performance liquid chromatography（HPLC） experiment group were used to test dopamine contents in striatum. Results： After exercise,the automatic movement ofrats in the exercise group significantlyincreased in Ex14 and Ex28 compared with the Sham group（P〈0.01）. HPLCresults indicated that dopamine in Ex28 group were higher than in Sham group（P 0.01）, but there are no significant changes between Ex7 and Ex14 compared with Sham rats（P〉 0.05）. There was an increased expression of GluR2/3 and a decreased GluR1 expression in Ex14 and Ex28 groups compared with the Sham group（Ex14： P 〈0.05; Ex28： P 〈0.01）while Ex7 groups did not（P〈0.05）. Conclusion： Our research show that the exercise protocol used is able to promote plastic GluR expression and dopamine contents during exercise, suggesting a specific involvement ofthese receptors in exercise-induced plasticityprocesses in brain.