柴胡皂苷a对ADHD模型大鼠前额叶中多巴胺含量及其合成、释放、清除信号通路的影响

Effects of Saikosaponin a on Dopamine Content and its Synthesis,Release, Clearance Signaling Pathway in Prefrontal Lobe of ADHD Model Rats

目的:探讨柴胡皂苷a对注意缺陷多动障碍模型——自发性高血压大鼠(SHR)前额叶多巴胺(DA)含量及其合成、释放及清除信号通路的影响。方法:按照随机区组法将50只SHR随机分为模型组、利他林组(2 mg/kg)阳性对照组及柴胡皂苷a低、中、高剂量(12.5、25、50 mg/kg)组,各10只,另将10只WKY大鼠作为正常对照组。各组大鼠灌胃给予相应药物,2次/d,于给药4 w后摘取大鼠脑组织。同时分别采用实时定量荧光PCR、蛋白质印迹法及免疫组织化学法检测各组大鼠前额叶及纹状体中TH、VMAT2、SNAP-25、Syntaxin-1a、DAT mRNA及蛋白表达,高效液相色谱荧光法检测各组大鼠前额叶中DA含量。结果:与正常对照组比较,模型组大鼠前额叶中TH、SNAP-25、Syntaxin-1a、VMAT2 mRNA和(或)蛋白表达显著降低,DAT蛋白表达及DA含量显著升高(P<0.05或P<0.01)。与模型组比较,柴胡皂苷a能使模型大鼠前额叶中TH、SNAP-25、Syntaxin-1a、VMAT2 mRNA和(或)蛋白表达及DA含量显著升高,DAT蛋白表达显著降低(P<0.05或P<0.01)。结论:柴胡皂苷a有增加ADHD模型大鼠前额叶多巴胺含量的作用,其作用机制可能与增加前额叶多巴胺的合成及释放,并减少多巴胺的重吸收有关。

Objective:To investigate the effects of saikosaponin a on the prefrontal dopamine(DA)content and its synthesis,release and clearance signaling pathways in a model of attention deficit hyperactivity disorder-spontaneously hypertensive rat(SHR).Methods:50 SHR were randomly divided into model group,ritalin positive control group(2 mg/kg),saikosaponin a low-,medium-and high-dose group(12.5,25,50 mg/kg)with 10 each,another 10 WKY rats were used as the normal control group.All rats were given intragastric administration,the frequency of intragastric administration was 2 times/d.The brain tissue of the rats was harvested after 4 w of treatment.Real-time quantitative fluorescent PCR,Western blot and immunohistochemistry were used to detect the expressions of TH,VMAT2,SNAP-25,Syntaxin-1 a and DAT mRNA and proteins in the prefrontal cortex and striatum of all rats.HPLC was used to detect the content of DA in the prefrontal cortex of each group.Results:Compared with the normal control group,the expressions of TH,SNAP-25,Syntaxin-1 a,VMAT2 proteins and(or)mRNA in the prefrontal cortex of the model group significantly decreased,while the content of DA and DAT protein expression significantly increased(P<0.05 or P<0.01).The mRNA and(or)protein expressions of TH,SNAP-25,VMAT2 and Syntaxin-1 a and DA content in the frontal lobe of the model rats were significantly increased by saikosaponin a,while the expression of DAT protein was significantly decreased(P<0.05 or P<0.01).Conclusion:Saikosaponin a can increase the content of dopamine in the frontal lobe of ADHD model rats.The mechanism of action may be related to the increase of dopamine synthesis and release in the frontal lobe and reduce the reabsorption of dopamine.