【作者】 徐丽；

【导师】 陈文芳；

【作者基本信息】 青岛大学 ， 生理学， 2007， 硕士

【摘要】 帕金森病(Parkinson’s disease,PD)是一种常见的中枢神经系统退行性疾病,其主要病理改变是中脑黑质致密部(substantia nigra pars compacta,SNpc)多巴胺(dopamine,DA)能神经元进行性变性、脱失并伴发黑质(substantia nigra,SN)纹状体(striatum,Str)轴突末梢DA耗竭。流行病学资料显示PD的发病率有明显的性别差异,男性高于女性,雌激素替代治疗可以减轻更年期妇女早期的PD症状。虽然动物实验及离体细胞培养实验均证实雌激素对中枢神经元具有保护作用,但大量的研究结果显示长期应用雌激素会增加乳腺癌、子宫内膜癌及中风等的发病率。雌激素替代治疗的副作用,限制了其在临床的长期应用。植物雌激素作为一类天然产品,具有类雌激素样作用,可清除自由基和抗氧化。人参皂甙Rg1是人参的主要活性成分,大量研究显示人参皂甙Rg1具有神经营养和神经保护作用。为探讨植物雌激素人参皂甙Rg1(ginsenoside Rg1)对6-羟基多巴(6-hydroxydopamine,6-OHDA)制备的去卵巢(ovaryectomy,OVX)PD模型大鼠黑质纹状体系统的保护作用及其机制,本研究应用6-OHDA制备去卵巢PD模型大鼠,腹腔注射Rg1或侧脑室同时给予胰岛素样生长因子Ⅰ受体(insulin-like growth factor-1 receptor,IGF-1R)阻断剂JB-1或雌激素受体(estrogen receptor,ER)阻断剂ICI182,780,观察阿朴吗啡(apomorphine,APO)诱导的大鼠旋转行为;应用高效液相色谱法检测大鼠Str内DA及其代谢物二羟基苯乙酸(dihydroxyphenylacetic acid,DOPAC)和高香草酸(homovanillic acid,HVA)的含量变化;应用免疫组织化学法、逆转录-聚合酶链式反应(RT-PCR)观察SN内酪氨酸羟化酶(tyrosine hydroxylase,TH)、多巴胺转运体(dopamine transporter,DAT)、Bcl-2蛋白和基因表达水平的变化。实验结果如下:1.6-OHDA制备的PD模型大鼠给予APO可成功诱导出旋转行为。当给予Rg1处理之后,其旋转行为改善,此作用可被IGF-1R阻断剂JB-1或ER阻断剂ICI182,780所阻断。2.6-OHDA模型组患侧Str内DA及其代谢产物DOPAC和HVA的含量较健侧明显降低差异有显著性(P＜0.01);Rg1给药组患侧Str内DA、DOPAC和HVA的含量较6-OHDA模型组患侧均明显增加,差别有统计学意义(P＜0.01),且此作用可被JB-1或ICI182,780所阻断。3.6-OHDA模型组患侧,SN区致密带TH免疫反应阳性神经元数目及基因表达明显减少,与健侧相比有显著统计学意义(P＜0.01):Rg1给药组患侧SN区致密带TH免疫反应阳性神经元数目及基因表达较6-OHDA模型组患侧明显增加(P＜0.01),此保护作用可被JB-1或ICI182,780所阻断。4.6-OHDA模型组患侧与健侧相比,SN区DAT蛋白和基因表达明显减少,差别有统计学意义(P＜0.01);Rg1给药组患侧SN区DAT蛋白和基因表达较6-OHDA模型组患侧明显增多(P＜0.01),此保护作用亦可被JB-1或ICI182,780所阻断。5.6-OHDA模型组患侧与健侧相比,SN区Bcl-2蛋白和基因表达明显减少,差别有统计学意义(P＜0.01);Rg1给药组患侧SN区Bcl-2蛋白和基因表达较6-OHDA模型组患侧明显增多(P＜0.01),此保护作用亦可被JB-1或ICI182,780所阻断。以上结果表明人参皂甙Rg1对6-OHDA诱导的PD模型大鼠黑质纹状体系统DA神经元具有明显的保护作用,其机制可能与IGF-IR途径与ER途径的相互作用有关。本实验中研究的人参皂甙Rg1对DA能神经元的保护作用以及对其可能机制的探讨,为传统中药的新用途和进一步开发为可用于临床防治PD的新药提供实验依据。更多还原

【Abstract】 Parkinson’s disease (PD) is a progressive neurodegenerative disorder characterized by selectively dopaminergic neuron loss in the substantia nigra pars compacta (SNpc) and the depletion of dopamine (DA) content in the striatum. Epidemiologic studys revealed that the prevalence of Parkinson disease is higher in males than in females. Estrogens may be involved the reason for the gender difference. Women treated with estrogen replacement therapy exhibit a reduced severity of PD. Although data suggest beneficial effects of estrogen in PD and the other senile diseases, many women turn to phtoestrogens as an alternative to hormone replacement therapy because of the undesirable side effects, such as increased risk of breast and endometrial cancer. Phytoestrogens are plant-derived compounds that structurally or functional mimic mammalian estrogens. Ginsenosides Rg1, the principal active components of ginseng, has neurotropic and neuroprotective effects on the nervous system either in vivo or in vitro, but the detail mechanism is not very clear. Our present study aims at investigating the neuroprotective effects and the possible mechanisms involved in mediating ginsenoside Rg1 actions in 6-OHDA-lesioned ovariectomized rat model of Parkinson’s disease. The contents of DA and its metabolites dihydroxy-phenylacetic acid (DOPAC) and homovanillic (HVA) in the striatum were determined by using high performance liquid chromatography-electrical chemical detection (HPLC-ECD). Results were as follows:1. Rg1 can ameliorate the rat’s rotation behavior induced by apomorphine. This effect could be partly blocked by IGF-1R antagonist JB-1 or ER antagonist ICI182,780.2. The DA, DOPAC and HVA levels in the Str of the injured side of PD rats were significantly decreased compared with the intact side (P<0.01). Rg1 treatment could reverse the decrease of DA, DOPAC and HVA induced by 6-OHDA and this effect could be completely blocked by JB-1 or ICI182,780 (P<0.01).3. The numbers of TH immunoreactive neurons and gene expressions decreased in the injured side of SN compared with that of uninjured side of SN (P<0.01), Rg1 treatment could increase TH immunoreactive neurons and gene expressions in the injured side of SN compared to the 6-OHDA group. This effect could be blocked by IGF-1R antagonist JB-1 or ER antagonist IC1182,780 (P<0.01).4. 6-OHDA -challenge with Rg1 treatment demonstrated reduced neurotoxicity with DAT protein and gene level in the substantial nigra. Cotreatment with JB-1 or ICI182,780 completely abolished the neuroprotective effects of Rg1 on the DAT protein and gene expressions.5. 6-OHDA -challenge with Rg1 treatment demonstrated reduced neurotoxicity with Bcl-2 protein and gene level in the substantial nigra. Cotreatment with JB-1 or 1CI182,780 completely abolished the neuroprotective effects of Rg1 on the Bcl-2 protein and gene expressions.These results demonstrated that ginsenoside Rg1 has neuroprotective effects on the dopaminergic neurons in the 6-OHDA induced OVX rat model of PD and its actions might involve activation of IGF-IR and ER signaling pathway. These results provide experimental evidence for the clinical application of ginsenoside Rg1 for prevention and treatment of PD.更多还原