蛋白酶体抑制剂诱导多巴胺能神经元变性伴包涵体形成

目的 观察蛋白酶体抑制剂诱导黑质多巴胺(DA)能神经元变性伴胞浆内包涵体形成，探讨蛋白酶体功能在帕金森病发病机制中的作用。方法将蛋白酶体抑制剂Lactacystin立体定向注射至大鼠黑质部位。免疫荧光观察黑质区DA神经元变性缺失及胶质细胞变化。免疫荧光双标法观察DA能神经元内蛋白聚集的包涵体及其主要成分α-共核蛋白(α-synuclein)、Parkin和泛素(ubiquitin)的表达。同时观察。DA能神经元发生细胞凋亡。结果注射Lactacystin第7天大鼠开始出现自发性活动减少，阿扑吗啡可诱导出旋转行为；3周后黑质部位酪氨酸羟化酶(TH)阳性细胞减少，呈剂量依赖性；小胶质细胞增生明显。TH与硫磺素、硫磺素与α-synuclein、硫磺素与Parkin、以及硫磺素与ubiquitin复合染色呈阳性；TH与TUNEL双染亦呈阳性。结论Lactacystin对多巴胺能神经元具有毒性作用，且导致蛋白聚集，包涵体形成。蛋白酶体功能异常可能在帕金森发病机制中起重要作用。     

蛋白酶体抑制剂诱导大鼠运动行为改变的研究

目的 观察蛋白酶体抑制剂诱导大鼠黑质变性及大鼠运动行为改变,探讨蛋白酶体功能下降在帕金森病发病机制中的作用.方法 将蛋白酶体抑制剂立体定向注射入大鼠左侧黑质致密部,对照组注射等体积的生理盐水.观察大鼠自主行为和阿朴吗啡诱导的旋转行为的改变.开野实验观察大鼠自发运动行为改变.免疫组织化学法观察黑质致密部及纹状体内酪氨酸羟化酶的表达.结果 Lactacystin组大鼠给药一周后出现自发性活动减少,动作缓慢,震颤、对外界刺激不自主竖毛,且症状逐步加重;阿朴吗啡可诱导出向健侧的旋转运动.开野实验中,Lactacystin组大鼠自发运动行为出现改变.三周后黑质部位酪氨酸羟化酶免疫阳性细胞及纹状体内酪氨酸羟化酶免疫阳性神经纤维减少.结论 蛋白酶体抑制剂Lactacystin单侧黑质致密部微量注射可以诱导大鼠黑质变性并出现运动行为改变,蛋白酶体抑制剂在帕金森病动物模型制备上有潜在价值,蛋白酶体功能下降可能在帕金森病发病机制中起重要作用.     

蛋白酶体功能与帕金森病相关性实验研究

目的 观察蛋白酶体抑制剂诱导大鼠黑质多巴胺能神经元α-突触核蛋白（α-synuclein，α-Syn）的表达及聚集．探讨蛋白酶体功能在帕金森病（PD）发病中的作用机制。方法采用立体定向将蛋白酶体抑制剂Lactacystin注射至大鼠黑质部位。以免疫荧光法观察黑质区多巴胺能神经元变性缺失，并应用免疫荧光双标法观察多巴胺能神经元内蛋白聚集的包涵体及其主要成分α-Syn的表达．然后通过原位杂交分析α-Syn mRNA表达及Western印迹法检测黑质α-Syn表达量改变。结果注射Lactacystin第7天大鼠开始出现自发性活动减少．阿扑吗啡尚可诱导出旋转行为；3周后患侧黑质部位酪氨酸羟化酶（TH）阳性细胞明显减少。TH与硫磺素、硫磺素与α-Syn复合染色呈阳性。α-Syn mRNA表达量升高，蛋白表达水平增加。结论Lactacystin诱导大鼠黑质细胞α-Syn表达升高并出现蛋白聚集可能是导致PD发病的机制之一。     

蛋白酶体抑制剂诱导帕金森病大鼠模型行为学退行性改变的研究

目的观察蛋白酶体抑制剂诱导的帕金森病(PD)行为学退行性变化,探索其发病机制。方法将32只大鼠随机分成实验组和对照组,每组16只,将蛋白酶体抑制剂Lactacystin立体定向注射到实验组大鼠左侧黑质致密部,对照组注射等体积生理盐水。术后1、3、5、7、9、11、14、18和21d,追踪观察大鼠自主行为和阿扑吗啡诱导的旋转行为变化;开野实验观察大鼠自发运动行为改变。结果实验组给药后,随着时间推移大鼠开始出现渐进性自发性活动减少、动作缓慢、对外界刺激不自主竖毛、震颤;阿扑吗啡诱导的向健侧旋转运动逐渐增多。开野实验结果显示:实验组大鼠自发运动行为出现渐进性异常改变。结论蛋白酶体抑制剂Lactacystin单侧黑质致密部微量注射诱导的大鼠行为学呈渐进性发展,符合PD发病过程,说明蛋白酶体功能下降可能在PD发病机制起重要作用。     

Lactacystin诱导的帕金森病大鼠模型病理退行性改变的研究

目的 观察Lactacystin诱导的帕金森病(PD)模型大鼠的病理退行性改变,探索其发病机制.方法 取成年健康SD大鼠32只,采用随机数字表法分为实验组(16只)和对照组(16只),实验组左侧黑质致密部(SNc)注射蛋白酶体抑制剂Lactacystin,对照组以等体积生理盐水代替.分别存注射后1、3、5、7、9、11、14和21 d,观察两组大鼠的行为学变化;应用HE染色观察小胶质细胞并计数,免疫组化检测黑质及纹状体组织罗暗算酪氨酸羟化酶(TH)神经元变化和RT-PCR检测黑质部TH和α-synuclein mRNA的表达.结果 与对照组相比,实验组大鼠逐渐出现行为学改变:HE染色显示小胶质细胞在注射Lactacystin后第1天为(3501.92±57.32)个,第7天为(4895.50±52.67)个,第21天为(5340.18±52.87)个,与对照组(3271.23±63.76)个相比增高,差异具有统计学意义(P＜0.05):免疫组化检测显示黑质中多巴胺(DA)神经元在注射Lactacystin后逐渐变性死亡,第7天神经元数为(568.57±36.39)个,第21天为(119.67±21.06)个,与对照组(679.76±30.24)个相比,差异具有统计学意义(P＜0.05);免疫组化检测纹状体TH免疫阳性纤维显示其在注射Lactacystin后逐渐稀疏,强度逐渐变弱,实验组TH免疫阳性纤维平均光密度第7天为(0.1953±0.0076),与对照组(0.2412±0.0067)相比,差异无统计学意义(P＞0.05),第21天为(0.0781±0.0013)个,与对照组(0.2412±0.0067)个相比降低,差异具有统计学意义(P＜0.05).同时,实验组mRNA检测显示,THmRNA表达越来越少,而α-synuclein mRNA在残存TH神经元中逐渐增多.结论 Lactacystin诱导的PD模型大鼠的病理呈退行性改变.符合PD发病的隐匿性、缓慢进展性特征.     

蛋白酶体抑制剂诱导多巴胺能神经元变性及诱导型一氧化氮合酶变化

目的探讨蛋白酶体（proteasome）功能下降在帕金森病（PD）发病机制中的作用，以及模型大鼠脑内黑质部位诱导型一氧化氮合酶（iNOS）是否参与蛋白酶体抑制剂Lactacystin诱导的多巴胺能神经元变性。方法将30只健康雄性SD大鼠分为5组（生理盐水对照组，1d组、3d组、1周组、3周组），每组6只。将蛋白酶体抑制剂Lactacystin立体定向注射至大鼠黑质部位，记录大鼠在不同时间点的行为学改变，并用免疫组化方法观察生理盐水对照组及不同时间点组（1d、3d，1周、3周）大鼠黑质区多巴胺能神经元变性及iNOS变化。结果Lactacystin注射1周后大鼠开始出现自发性活动减少，阿朴吗啡可诱导出旋转行为；3周后，30min旋转次数为258．90±11．56；实验3周组黑质部位TH阳性细胞减少。1d后iNOS阳性细胞明显增多，3d时达高峰，1周后开始下降，3周时基本消失。结论蛋白酶体功能下降可能是多巴胺能神经元变性的始动因素，而iNOS上调可能是多巴胺能神经元变性的重要过程。     

应用蛋白酶体抑制剂Lactacystin建立有Lewy体的帕金森病大鼠模型

目的建立符合帕金森病(PD)病理特征———黑质细胞有Lewy体的PD大鼠模型。方法分别在大鼠一侧黑质致密部注射蛋白酶体抑制剂Lactacystin8mg(Lactacystin组)、等体积生理盐水(NS组)和6-羟基多巴胺(6-OHDA组)12mg;观察大鼠自主行为和阿朴吗啡诱导的旋转行为;光镜下观察中脑组织学改变;应用免疫组化染色观察黑质细胞α-synuclein表达和酪氨酸羟化酶(TH)阳性细胞数;测定纹状体区多巴胺和高香草酸含量。结果NS组大鼠未见行为异常;Lactacystin组大鼠出现进行性的运动迟缓、少动、震颤、头向健侧倾斜,注射阿朴吗啡后出现向健侧旋转运动;给药后3周黑质部TH阳性细胞数较NS组减少了83.29%(P<0.01),部分黑质细胞内出现α-synuclein免疫反应呈强阳性的Lewy体;纹状体多巴胺和高香草酸含量(154.82±37.17,98.66±18.81)较NS组明显减少(822.87±131.25,617.77±95.74)(均P<0.01);6-OHDA组大鼠出现与Lactacystin组类似的行为变化,黑质细胞亦显著减少,但未见Lewy体。结论利用蛋白酶体抑制剂Lactacystin阻碍α-synuclein的降解可以建立有Lewy体的PD大鼠模型。     

蛋白酶体抑制剂诱导帕金森病大鼠模型海马区HSP70表达

目的观察蛋白酶体抑制剂Lactacystin诱导帕金森病大鼠模型海马区HSP70表达。方法将Lactacystin 10μg（2μl）经立体定向仪注射到大鼠（Lactacystin组,n=36）左侧黑质致密部,对照组（n=36）以等体积生理盐水代替;分别在药物注射后24h、3d、5d、7d、9d、11d、14d、18d和21d提取海马标本,通过免疫组化和RT-PCR观察HSP70的表达。结果Lactacystin组大鼠海马区HSP70表达较对照组高,表现为注药24h后表达开始增高,5d达高峰,11d开始减少;且海马区表达分布呈CA3〉CA2〉CA1。结论Lactacystin诱导帕金森病大鼠海马区HSP70表达增高,且呈明显区域性和时间依从性;增加的热休克蛋白可能参与拮抗蛋白酶体抑制毒性而起到神经细胞保护作用。     

6-羟基多巴定向注射建立帕金森病大鼠模型的实验研究

目的探讨立体定向间隔注射6-羟基多巴(6-OHDA)毁损黑质致密部(SNc)和中脑腹侧被盖(VTA)建立类似于人类帕金森病(PD)中晚期的PD大鼠模型方法。方法近交系Wistar大鼠50只,脑立体定向将6-OHDA注入大鼠右侧VTA及SNc,间隔两周,对阿朴吗啡(Apo)诱发旋转后旋转不明显或无稳定左侧旋转模型再次制模,并观察大鼠行为学改变,免疫组化检测黑质多巴胺(DA)能神经元的数量以及高效液相-荧光法检测黑质纹状体中DA含量的变化。结果(1)50只大鼠中有41只经APO诱导表现为恒定左侧旋转且结果稳定,旋转圈数>210r/30min,视为成功PD大鼠模型,部分大鼠伴有震颤、活动迟缓、嗅探、觅食、竖尾等异常行为改变,并且可持续存在16周;(2)免疫组化结果:PD大鼠模型毁损侧黑质区多巴胺能神经元较对侧及对照组减少大于90%;(3)PD大鼠右侧黑质纹状体中DA含量较左侧及对照组减少90%以上。结论6-OHDA毁损SNc及VTA间隔注射法可有效建立模拟人类PD中晚期的大鼠PD模型。     

帕金森病模型鼠黑质α-突触核蛋白表达升高并集聚

目的观察低剂量1-甲基-4-苯基-1,2,3,6-四氢吡啶(MPTP)对小鼠黑质多巴胺能神经元α-突触核蛋白表达的影响。方法C57BL小鼠腹腔注射MPTP20mg/kg体重,每周注射1次连续3周,观察小鼠行为改变,应用逆转录-聚合酶链反应(RT-PCR)、Western印迹法、免疫组化染色检测α-突触核蛋白表达,荧光双标染色观察多巴胺能神经元内α-突触核蛋白聚集。结果与注射生理盐水组相比,注射MPTP组小鼠出现暂时性躯干震颤、竖毛、动作减少等;α-突触核蛋白基因表达百分比(79·5%±0·8%,生理盐水组为19·2%±3·3%,P<0·05)及蛋白表达百分比(82·2%±4·1%,生理盐水组为18·5%±1·0%,P<0·05)均明显增加;黑质部酪氨酸羟化酶(TH)阳性细胞数减少,α-突触核蛋白阳性细胞数增加;α-突触核蛋白与硫磺素S、TH与硫磺素S复合定位染色的阳性细胞数均升高。结论低剂量MPTP可诱导小鼠行为改变,黑质多巴胺能神经元α-突触核蛋白表达升高,并出现蛋白聚集。     

Proteasome inhibition causes nigral degeneration with inclusion bodies in rats

Structural and functional defects in 26/20S proteasomes occur in the substantia nigra pars compacta and may underlie protein accumulation, Lewy body formation and dopaminergic neuronal death in Parkinson's disease. We therefore determined the pathogenicity of proteasomal impairment following stereotaxic unilateral infusion of lactacystin, a selective proteasome inhibitor, into the substantia nigra pars compacta of rats. These animals became progressively bradykinetic, adopted a stooped posture and displayed contralateral head tilting. Administration of apomorphine to lactacystin-treated rats reversed behavioral abnormalities and induced contralateral rotations. Lactacystin caused dose-dependent degeneration of dopaminergic cell bodies and processes with the cytoplasmic accumulation and aggregation of alpha-synuclein to form inclusion bodies. These findings support the notion that failure of the ubiquitin-proteasome system to degrade and clear unwanted proteins is an important etiopathogenic factor in Parkinson's disease.     

c-Jun N-terminal kinase mediates lactacystin-induced dopamine neuron degeneration

Parkinson disease is characterized by the progressive loss of dopaminergic neurons in the substantia nigra pars compacta. It has been proposed that dysfunction of the ubiquitin proteasome system plays an important role in the pathogenesis of Parkinson disease, but the mechanisms underlying ubiquitin proteasome system-related neuron degeneration are unknown. Here, we demonstrate that the proteasome inhibitor lactacystin induces phosphorylation of c-Jun N-terminal kinase (JNK) and c-Jun, the release of cytochrome c, activation of both caspase-9 and caspase-3, and sequential apoptosis of dopaminergic neurons in vitro. Most of these effects can be attenuated by the JNK inhibitor SP600125. Furthermore, infusion of lactacystin in rats in vivo also leads to phosphorylation of JNK before nigral neuron loss; chronic administration of SP600125 also blocks this loss. These results indicate that JNK is involved in proteasome inhibition-induced dopaminergic neuron degeneration through caspase-3-mediated apoptotic pathways, suggesting that this kinase may be a therapeutic target for the prevention of substantia nigra pars compacta degeneration in Parkinson disease patients.     

Anchanling reduces pathology in a lactacystin-induced Parkinson’s disease model

A rat model of Parkinson’s disease was induced by injecting lactacystin stereotaxically into the left mesencephalic ventral tegmental area and substantia nigra pars compacta. After rats were intragastrically perfused with Anchanling, a Chinese medicine, mainly composed of magnolol, for 5 weeks, when compared with Parkinson’s disease model rats, tyrosine hydroxylase expression was increased, α-synuclein and ubiquitin expression was decreased, substantia nigra cell apoptosis was reduced, and apomorphine-induced rotational behavior was improved. Results suggested that Anchanling can ameliorate Parkinson’s disease pathology possibly by enhancing degradation activity of the ubiquitin-proteasome system.     

Demonstration of the nigrostriatal projection by silver staining after nigral injections of 6-hydroxydopamine

Lesions of the substantia nigra of rats were made by local injections of 6-hydroxydopamine. The degenerative changes in the brain were studied by means of the Fink-Heimer technique. Survival times of 2 or 3 days were optimal for the demonstration of degeneration. Extensive necrotic changes were observed in neurons of the substantia nigra pars compacta following 6-hydroxydopamine injections; control injections did not produce necrosis. Dense fields of terminal degeneration were observed in the caudate of the 6-hydroxydopamine treated rats but not in the caudates of the control animals. A comparison was made on the amount of degeneration present in the ventral nucleus of the thalamus after three types of lesions: (a) nigral injection of 6-hydroxydopamine; (b) nigral injection of carrier solution (control); and (c) electrolytic lesion of the substantia nigra. Lesions (a) and (b) produced only small amounts of thalamic degeneration, while lesion (c) produced extensive terminal degeneration in the ventral thalamic nucleus. The toxic effects of nigral injections of 6-hydroxydopamine were confined to the dopaminergic neurons of the substantia nigra pars compacta; nondopaminergic neurons of the substantia nigra pars reticulata, and their thalamic projection field, appeared normal in silver stains.     

Substance P synaptic interactions with GABAergic and dopaminergic neurons in rat substantia nigra: An ultrastructural doublelabeling immunocytochemical study

The distribution of substance P (SP), tyrosine hydroxylase (TH), and glutamic acid decarboxylase (GAD) immunoreactivity in the substantia nigra of the rat was studied by means of an ultrastructural double-labeling immunocytochemical method. Direct synaptic contact between SP-immunoreactive terminals and GAD-positive nigral neurons was more often observed in the pars lateralis than the pars reticularis and was rarely observed in the pars compacta. Substance P-positive terminals also formed synapses with cell bodies and dendrites of TH-positive, dopaminergic neurons in the pars compacta and pars reticulata. Multiple SP-immunoreactive terminals were often observed with symmetrical and, less frequently, asymmetrical synapses on individual TH-containing dendrites. Evidence of SP-containing terminals contacting both GABAergic and dopaminergic neurons in the substantia nigra suggests a direct excitatory action upon nigral projection neurons.     

Caspase inhibition protects nigral neurons against 6-OHDA-induced retrograde degeneration

6-Hydroxydopamine (6-OHDA) administered intrastriatally to adult rats in a single injection causes neurodegeneration of the nigrostriatal pathway and loss of > 50% of dopamine neurons in substantia nigra pars compacta 30 days after administration. The death of nigral neurons occurs, at least partially, by a caspase-mediated mechanism. The nigral loss of dopaminergic neurons could be prevented by stereotaxical administration of zVAD.fmk, a caspase inhibitor, into the substantia nigra, indicating that 6-OHDA-induced nigrostriatal degeneration involves caspase activation. These results suggest that caspases are probably involved in neurodegenerative chronic processes such as Parkinson's disease and might be considered as possible targets in the treatment of such neurological disorders.