静宁颗粒对注意力缺陷多动障碍模型大鼠认知功能及纹状体单胺类的影响

目的采用Morris水迷宫检测注意力缺陷多动障碍(Attention Deficit Hyperactivity Disorder,ADHD)模型动物-幼年自发性高血压大鼠(Spontaneous HypertensiveRats,SHR)学习记忆能力,评价静宁颗粒对SHR大鼠认知功能的影响,并观察静宁颗粒对SHR大鼠纹状体单胺类神经递质和多巴胺转运体(DAT)mRNA表达的影响,并探讨该药治疗ADHD的作用机制。方法60只幼年雄性SHR大鼠随机分为静宁颗粒高、中、低剂量组、盐酸哌甲酯组、盐酸托莫西汀组、模型对照组,每组10只;正常组为10只同龄Wistar大鼠。连续灌胃给药6周后,采用高效液相-电化学(HPLC-ECD)法检测各组大鼠纹状体单胺类神经递质含量;Real-time PCR法检测各组大鼠纹状体DAT mRNA表达水平。实验过程中,静宁颗粒低剂量组大鼠因灌胃处理不当死亡1只,因此样本量为9只,余组均为10只。结果静宁颗粒中、低剂量组,与盐酸托莫西汀组均能改善SHR大鼠学习记忆能力,从而改善认知功能(P<0.05),但盐酸托莫西汀组大鼠目标象限停留时间较静宁颗粒中、低剂量组增加,静宁颗粒对SHR大鼠认知功能的改善不及盐酸托莫西汀。纹状体DAT基因表达量依次为静宁颗粒高剂量组>盐酸托莫西汀组>静宁颗粒低剂量组>盐酸哌甲酯组>静宁颗粒中剂量组。与模型对照组比较,静宁颗粒中、低剂量组和盐酸哌甲酯组大鼠纹状体中DAT基因相对表达量降低,其中静宁颗粒中剂量组降低更明显。纹状体单胺类神经递质检测:正常组及静宁低剂量组大鼠脑组织纹状体中去甲肾上腺素(NE)、多巴胺(DA)、5-羟色胺(5-HT)含量增高(P<0.05),盐酸托莫西汀组3,4-二羟基苯乙酸(DOPAC)、5-HT含量增高(P<0.05),与盐酸托莫西汀组比较,静宁颗粒中剂量组5-羟吲哚乙酸(5-HIAA)降低(P<0.05)。结论模型对照组大鼠的认知功能明显降低,中药静宁颗粒可以显著改善ADHD动物模型的认知功能。静宁颗粒治疗ADHD的可能机制之一与其下调纹状体DAT mRNA表达水平,上调纹状体DA、NE、5-HT的含量,以及协调平衡单胺类神经递质的作用有关。

Effect of Jingning Granules on cognitive function and striatal monoamine mechanism in rat models with attention deficit hyperactivity disorder

Objective To evaluate the learning and memory ability of young spontaneously hypertensive rats(SHR),an Attention Deficit Hyperactivity Disorder(ADHD)model animal,by using Morris water maze,to evaluate the effect of Jingning Granules on the cognitive function of SHR Rats,to investigate the mRNA expression of the striatum single amine neurotransmitter and dopamine transporter(DAT),and to study the mechanism of the drug in treating ADHD.Methods A total of 60 young male SHR rats were randomly divided into high,medium and low dose groups of Jingning Granules,methylphenidate hydrochloride group(MH),tomoxetine hydrochloride group(TH)and model group,with 10 rats in each group.The normal group included 10 Wistar rats of the same age.After 6 weeks of continuous gavage,the content of monoamine neurotransmitter in the rat striatum was determined by HPLC-ECD.Real-time PCR was used to detect the expression level of DAT mRNA in rat striatum.During the experiment,one rat in the low-dose group died due to improper gavage treatment,so the sample size in the low-dose group was nine,and all the other groups were ten.Results In the medium-dose and low-dose groups,and the TH group,the learning and memory ability of SHR rats was improved,and the cognitive function was improved(P<0.05),however,the time of target quadrant in TH group was longer than in the medium-dose and low-dose group,indicating that Jingning Granules had a weaker effect of improving the cognitive function of SHR rats than tomoxetine hydrochloride.The expression of striatum DAT gene was successively in the high-dose group>TH group>low-dose group>MH group>medium-dose group.Compared with the model group,the relative expression of DAT gene in the rat striatum in medium-dose group,low-dose groups and MH group decreased,and the medium-dose group had more significant decrease than the low-dose group and MH group.Detection of striatum monoamine neurotransmitter:the content of NE,DA and 5-HT in the striatum of the brain tissues of rats in the normal group and the low-dose group increased(P<0.05),and the content of DOPAC and 5-HT in the TH group increased(P<0.05);compared with that in the TH group,5-HIAA in the medium-dose group decreased(P<0.05).Conclusion The cognitive function of rats in the model group was significantly decreased,and Jingning Granules could significantly improve the cognitive function of ADHD animal model.One of the possible mechanisms of Jingning Granules in treating ADHD might be related to the down-regulation of striatum DAT mRNA expression,up-regulation of striatum DA,NE and 5-HT,and the role of coordinating and balancing monoamine neurotransmitters.