【作者】 顾兵；

【导师】 胡刚； 张颖冬；

【作者基本信息】 南京医科大学 ， 药理学， 2003， 博士

【摘要】 国外近期的统计资料表明，帕金森病（Parkinson’s disease，PD）的发病率为总人口的0.1％～0.2％，其中在55岁以上人口占1.4％。社会老龄化使得PD发病率呈明显上升趋势。尽管PD病因学研究备受各国学者的广泛关注，PD的病因和发病机制至今仍未阐明。目前认为PD的发生是由于中脑黑质多巴胺（DA）能神经元选择性退变，并且残存的神经元中出现嗜酸性包涵体。黑质致密部（SNc）DA能神经元的缺失，最终导致间接通路活性的增强，尤其是丘脑底核（STN）谷氨酸（Glu）能神经元的活性增强，从而出现锥体外系病变。手术治疗旨在减弱间接通路活性的传导，但其侵害性大、费用昂贵，只适合为数较少的患者。长期应用左旋多巴复合外周脱羧酶抑制剂的DA替代疗法，大部分患者出现疗效减退，运动波动等各种不良反应。因而，神经药理学家转向开发一种能间接减弱间接通路传导的抗PD药物。 Glu和γ-氨基丁酸（GABA）是脑内两种主要的兴奋性和抑制性神经递质，它们的正常传导是维持基底神经节（BG）运动环路生理功能的必需条件。依据运动环路功能解剖理论，在PD中DA D₂受体介导的对纹状体-苍白球神经元抑制作用的减弱，导致直接通路的活性降低，间接通路的Glu能传导明显增强。而STN至苍白球内侧段/黑质网状区（GPi/SNr）的Glu能投射活性增加，使其发出的GABA能投射对丘脑的抑制增强，使输出结构对丘脑的紧张性抑制加剧。因而，通过增强DA能的神经传导或者遏制Glu能兴奋性传导，降低间接通路的活性，有望能最终治疗PD。 Glu与PD发病机制的密切相关，不仅因为运动环路中存在继发的Glu能传导障碍，而且Glu作为兴奋性氨基酸可造成神经元的损伤。STN将 南京医科大学博士学位论文Gill能神经元的兴奋性淑到黑质，而当 SNc DA能神经元损伤后，Gill能神经元便会异常活跃，使oU释放量增加，导致““大量内流，造成神经元内 of》超载，触发一系列 c／片关的a＃x反应，致使＋＋能神n元变性和／或坏死。由于DA分泌减少削弱了对STN的抑制，增强了兴奋性传出神经元的放电，进一步加重兴奋性毒性。另一种可能是通过增加一氧化氮合酶64合成，导致NO生成增加，损伤线粒体呼吸链酶复合物1。而线粒体功能缺陷致使生理浓度的Gill介导“”内流，间接地产生兴奋性神经毒性和黑质谷耽甘肽（GSH）的水平降低。在这过程中，兴奋性神经毒性，线粒体功能缺失，自由基生成增加和细胞内灯“超载等一系列病理改变紧密相联，任何一个环节损伤都可导致DA能神经元退变。 Gill主要是通过活化突触膜上的受体发挥生理效应。Gill受体可分成亲离子型谷氨酸受体门GluRs)和亲代谢型谷氨酸受体（mGluRs）两大类。在 BG对运动指今的加工传导过程中，mGluRs发挥着重要的调控作用。目前证实 mGluRs有三组 8个亚型，它们都与 G蛋白相偶联。许多研究表明第 1组的 mGluRs激活，使蛋白激酶 C (PL活化；促使N水解产生D。和DAG，增强由iGl恤异常所介导的神经兴奋毒性。第1组mGluRs位于突触后膜上，分布在离子通道型受体的边缘，发挥突触后抑制效应。第11，Ill组6b mGluRs激活，可抑制腺菩酸环化酶 (A活性，使 cAW生成减少，N可抑制电压依赖性钙通道的活性。位于突触前膜上第 Ill组的mGluRs激活，可以减少Gin释放。突触前膜上的mGluRs作为自身受体负反馈调节O 传导；而作为DA能神经末梢的突触前受体，能调节DA释放和DA能神经元放电。定位在突触后膜上的mGluRs调节神经元兴奋性和介导通过iGlllRs 的电流。免疫组化和原位杂交技术的运用，揭示mGIuRs在黑质一纹状体部位的表达密度较高，且存在亚型的区域性分布。 鉴于mGluRs在快速m 兴奋性突触传递上发挥娜细的效应，并不存在于自主神经系统的靶器官上，各亚型的分布又有一定的特征性，mGluRs可望成为新一代疗效高，副作用少的抗PD的药物靶标。本文工作就是在整体行为学，神经生化，组织病理学和细胞等多水平多层次探讨mGluRs与PD发生的相关性，为探索PD的临床治疗和开拓新一代治疗药 3 南京医科大学博士学位论文物积累学术和实验数据。第一部分亲代谢型脆酸受体配捌黑质6－OHDA损毁大鼠的抗氧化作用目 的：探讨亲代谢型谷氨酸受体（SGlllRS）配基对PD模型大鼠的抗氧化作用。方 法：采用 6－羟基多巴单侧黑质损毁建立 PD大鼠模型，应用化学比色法测定血清总抗氧化能力（TAOC）抑制活性氧能力（ROS）和谷耽甘肽（GSH）含量。结 果：与模型对照组相比，I组二桔抗剂SIB－1893、11组 mGluRs激动剂 APDC、Ill组 mGluRs激动齐 L－SOP和L．DOM均能增加血清IAOC和GSH水平，提高清除ROS能力，尤以APDC组作用最为显著。结 论：I组mGl顺桔抗剂和11，Ill组mGluRs激动剂对6－羟基多巴损毁大鼠具有部分抗氧化功能，有利于机体减轻氧化应激所致的损伤。更多还原

【Abstract】 Parkinson’s disease (PD) is one of the most common neurodegenerative disorders, afflicting almost approximately 1.4% of the population over the age of 55, the mean age at which the disease is first diagnosed. Prevalence and incidence will both increase steadily with the ageing population of the world. It has formed an increasing economic burden for society and also become an ever more urgent international healthcare concern.PD is named after the physician James Parkinson, who published a formal description of the disorder in 1817 entitled " An Essay on the Shaking Palsy." For this reason, Parkinson’s disease is sometimes also referred to as shaking palsy or paralysis agitans. This disease is characterized clinically by bradykinesia (slowness of movement), muscular rigidity, tremor at rest, and postural abnormalities. These clinical symptoms result from the highly selective degeneration of a small group of neuromelanin-containing dopaminergic neurons in the midbrain. Many surviving neurons contain large, cytoplasmic, proteinaceous inclusions known as Lewy bodies, which are the pathological hallmark of PD. However, these symptoms do not appear until there is approximately a 70-80% reduction in the dopamine levels in the striatum. Surprisingly, no simple and reliable early-detection tests exist to predict persons at risk for PD long before they ever show overt signs of this disease. Although the symptoms and neuropathology of PD have been well characterized, the underlying mechanisms and causes of the disease remain largely enigmatic.In PD, the degeneration of dopaminergic neurons of the substantia nigra pars compacta (SNc) triggers a cascade of functional changes affecting thewhole basal ganglia (BG) network. The most relevant alterations affect the output nuclei of the circuit, the medial globus pallidus and substantia nigra pars reticulata (SNr), which become hyperactive. Such hyperactivity is sustained by the enhanced glutamatergic inputs that the output nuclei receive from the subthalamic nucleus. The overactivity of the glutamatergic STN projection to the BG output nuclei results in an inhibition of thalamocortical neurons. An imbalance of activity between the direct and indirect striatofugal pathways in favor of the indirect pathway is thought to underlie most symptoms of PD. Recently developed surgical therapies that are aimed at reducing activity through the indirect pathway, have been distinctly effective. Unfortunately, these approaches are highly invasive, extremely expensive, and assessable to a small minority of patients. Long-term effects are unknown, and surgical therapies only reserved for patients that can no longer be helped by dopamine replacement therapy. Thus new effort has been dedicated to finding pharmacological treatment options that will be effective in reducing transmission through the indirect pathway. The current pharmacotherapies are aimed at replacing the missing dopamine. DA precursor L-Dopa and/or DA agonists, has been the mainstay of pharmacotherapy for this disease. However, treatment with these dopaminomimetics does not mitigate progression of the process underlying PD, a factor that is thought to be causatively involved in the declining efficacy and occurrence of motor complications upon continued pharmacotherapy with such compounds. To optimally manage PD, there is still a strong requirement for drugs capable of retarding or, ideally, halting the ongoing degeneration of dopaminergic neurons in the substantia nigra. This realization has led to intensive investigation of the neuroprotective potential of various agents.Glutamate and y -amino butyric acid (GABA), respectively, are the major excitatory and inhibitory neurotransmitters in the CNS, provide the outcoming and incoming fast signals through the BG. The BG are a group of interconnected subcortical nuclei that, together with the thalamus and motor cortex, comprise the motor circuit responsible for the fine coordination of voluntary motor function. In PD, degeneration of the nigrostriatal pathway and subseque更多还原