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。     

百草枯诱导小鼠α-突触核蛋白表达升高并聚集的实验研究

目的观察除草剂百草枯诱导小鼠黑质细胞α-突触核蛋白(α—synuclein，α-syn)表达及聚集，探讨环境因素在帕金森病(Parkinsondisease，PD)发病中的作用机制。方法C57BL小鼠按体重10mg／kg经腹腔注射百草枯，应用原位杂交、RT—PCR分析α—syn mRNA表达．免疫组化、免疫荧光双标染色观察黑质区α—syn显色．并进一步确定表达rsyn的神经元表型及α—syn聚集。结果注射百草枯组小鼠黑质区α—syn mRNA表达量升高，rsyn阳性细胞数相对增加；rsyn与硫磺素、酩氨酸羟化酶(tyroxine hydroxylase，TH)及硫磺素复合染色的阳性细胞数均升高。结论百草枯诱导小鼠黑质细胞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。     

pVAX1-IL4/SYN-B核酸疫苗对鱼藤酮慢性帕金森病小鼠的治疗作用

目的探讨优化人α-突触核蛋白(humanα-synuclein,hα-syn)核酸疫苗pVAX1-IL4/SYN-B对鱼藤酮慢性帕金森病小鼠的治疗效果。方法采用鱼藤酮1 mg/kg给予背部皮下注射,1次/d,连续注射40 d,建立慢性帕金森病小鼠模型。建模后小鼠随机分为3组:核酸疫苗组、空质粒组、PBS组(n=8)。于小鼠双侧后肢胫前肌部位,分别注射pVAX1-IL4/SYN-B核酸疫苗,空质粒pVAX1,PBS各100μL,共免疫3次,每次间隔3周。末次免疫后2周,观察小鼠行为学变化;免疫组化方法检测小鼠脑黑质致密部α-syn表达和酪氨酸羟化酶阳性细胞数目变化;RT-PCR检测α-syn mRNA表达情况。结果行为学观察各组小鼠自由活动实验显示,核酸疫苗组与空质粒组及PBS组小鼠移动格子数和下肢站立次数均有明显改善(P<0.05)。免疫组化检测发现核酸疫苗组小鼠与空质粒组、PBS组相比,TH阳性细胞数增加51.43%、59.00%(P<0.05),α-syn表达减少45.64%、43.28%,(P<0.05)。RT-PCR检测发现核酸疫苗组α-syn mRNA表达水平(0.37±0.17)较空质粒组(0.80±0.01)及PBS组(0.74±0.05)明显减少(P<0.05)。结论 hα-syn核酸疫苗有较强改善帕金森病小鼠行为学的作用;能有效改善鱼藤酮神经毒素对黑质多巴胺能神经元的损害,能对帕金森病小鼠产生较好的免疫治疗作用。     

P2X4R过表达对帕金森病模型鼠脑黑质中白介素-1β、α突触核蛋白及多巴胺能神经元的影响

目的探讨使用慢病毒过表达P2X4R嘌呤受体(P2X4R)对帕金森病(PD)模型大鼠脑黑质中白介素-1β(IL-1β)和α突触核蛋白的表达及多巴胺能神经元数量的影响。方法 Wistar雄性大鼠,体质量200～250 g,随机分为6组(均n=20)。经立体定向定位左侧黑质,对照组:注入含0. 02%维生素C的生理盐水; PD组:注入6-羟基多巴胺(6-OHDA);目的基因阴性对照组:注入携带过表达P2X4R的慢病毒;空载病毒阴性对照组:注入空载病毒;目的基因阴性对照+PD组:注入携带过表达P2X4R的慢病毒1周后再注射6-OHDA;空载病毒阴性对照+PD组:注入空载病毒1周后再注射6-OHDA。模型判定成功后处死大鼠取左侧黑质,Western blot法检测各组黑质P2X4R、IL-1β、α突触核蛋白表达水平;免疫荧光染色法检测各组黑质酪氨酸羟化酶(TH)阳性多巴胺能神经细胞数的变化。结果①与PD组和空载病毒阴性对照+PD组比较,目的基因阴性对照+PD组P2X4R(P 0. 001)、IL-1β(P 0. 001)和α突触核蛋白(P 0. 01)相对表达量增加;②与PD组和空载病毒阴性对照+PD组比较,目的基因阴性对照+PD组TH阳性多巴胺能神经元数量明显减少(P 0. 001)。结论慢病毒介导P2X4R过表达可上调PD模型大鼠黑质中IL-1β和α-突触核蛋白表达水平、减少TH阳性多巴胺能神经细胞数;小胶质细胞的炎症反应增强,α-突触核蛋白沉积增加,对多巴胺能神经元有一定的损伤作用。     

沉默信息调节因子1/p53信号通路参与MPTP诱导的帕金森病小鼠多巴胺能神经元丢失

目的研究沉默信息调节因子1(SIRT1)和p53在MPTP诱导的帕金森病(PD)小鼠模型多巴胺能神经元凋亡中的可能作用。方法将健康雄性C57BL/6小鼠随机分为对照组、MPTP组,采用行为学方法检测行为学改变,高效液相色谱(HPLC)检测多巴胺(DA)、二羟基苯乙酸(DOPAC)和高香草酸(HVA)的含量变化,免疫荧光染色法观察两组小鼠黑质酪氨酸羟化酶(TH)阳性神经元数目的变化及SIRT1表达情况,TUNEL法观察黑质细胞凋亡情况,Western blot法检测TH、SIRT1、p53、乙酰化p53 (ac-p53)、B淋巴细胞瘤-2基因(Bcl-2)和Bax的表达情况。结果行为学结果显示MPTP组小鼠爬杆转向时间及爬杆总时间均较对照组小鼠显著延长(P 0. 01)。HPLC结果提示MPTP组的DA、DOPAC及HVA含量较对照组显著下降(P 0. 01)。免疫荧光结果显示MPTP小鼠黑质区TH阳性神经元数目及SIRT1表达较对照组均显著减少。TUNEL检测结果显示,与对照组相比,MPTP组凋亡阳性细胞数明显增多。Western blot结果显示,与对照组相比,MPTP组的TH、SIRT1、Bcl-2蛋白表达显著下降(P 0. 01),p53、ac-p53、Bax蛋白表达显著升高(P 0. 01)。结论MPTP模型小鼠行为学异常、TH阳性神经元减少、DA及其代谢产物下降提示成功复制PD动物模型,同时MPTP模型小鼠的SIRT1、p53及凋亡相关蛋白表达异常,提示该信号通路可能参与了PD的疾病过程。     

枸杞多糖对帕金森病小鼠的抗氧化作用和神经保护效应

目的研究枸杞多糖(Lycium barum polysaccharide,LBP)对帕金森病(Parkinson disease,PD)小鼠黑质多巴胺(dopamine,DA)能神经元的影响。方法采用MPTP制备PD小鼠模型,经左旋多巴(Levodopa,LDOPA)和LBP处理后,用爬杆实验评价各组小鼠的行为表现,通过酪氨酸羟化酶(tyrosine hydroxylase,TH)免疫组织化学染色观察黑质致密部DA能神经元存活情况,并用生化技术对中脑组织超氧化物歧化酶(super oxidase dismutase,SOD)、谷胱甘肽过氧化物酶(glutathione peroxidase,GSH-Px)和过氧化氢酶(catalase, CAT)活力及丙二醛(malonaldehyde, MDA)含量进行检测。结果 MPTP制备的PD模型小鼠爬杆实验得分远低于对照组(3.53±1.32 vs. 7.61±1.53,P0.01),黑质致密部TH阳性神经元数量较对照组有大幅减少(340±31 vs. 1204±112,P0.01),中脑组织SOD、GSH-Px和CAT酶活力也显著低于对照组,而MDA含量则显著高于对照组(P0.01)。经过L-DOPA处理的小鼠爬杆实验得分较MPTP组有大幅改善(6.87±1.51 vs. 3.53±1.32,P0.01),但TH阳性神经元数量仍较对照组有显著下降(295±63 vs. 1204±112,P0.01),中脑SOD、GSH-Px和CAT酶活力甚至低于MPTP组小鼠,而MDA含量则高于MPTP组(P0.05)。经过50 mg/kg和100 mg/kg LBP处理的小鼠爬杆实验得分均高于MPTP组(5.07±1.28 vs. 3.53±1.32;5.20±1.37 vs. 3.53±1.32,P0.01),而低于对照组和L-DOPA组(P0.05);TH阳性神经元数量也较MPTP组(655±78 vs. 340±31;704±38 vs. 340±31,P0.01)或L-DOPA组(655±78 vs. 295±63;704±38 vs. 295±63,P0.01)明显增多,但仍少于对照组(P0.01);SOD、GSH-Px和CAT酶活力均较MPTP组或L-DOPA组有显著升高,MDA含量则较上述两组有显著下降(P0.01)。结论 LBP能有效降低PD小鼠中脑氧化应激损伤,对黑质致密部DA能神经元起到保护作用。     

“抗帕颗粒”对帕金森病模型鼠α-syn异常聚集的影响

目的探讨"抗帕颗粒"对1-甲基-4-苯基-1,2,3,6-四氢吡啶(MPTP)帕金森病(PD)模型小鼠黑质纹状体区α-突触共核蛋白(α-syn)异常聚集的影响。方法 90只健康雄性C57BL/6小鼠,鼠龄8~12w。随机分为3组,正常对照组30只、PD模型对照组30只、PD模型干预组30只。MPTP腹腔注射40mg·Kg-1·d-1×7制备小鼠PD模型;正常对照组及PD模型对照组予生理盐水1ml·d-1灌胃;PD模型干预组给予"抗帕颗粒"40mg·kg-1·d-1灌胃,连续喂养4个月。比较分析各组4月时黑质纹状体区α-syn聚集情况。结果 (1)正常对照组30只(30/30只)最终均存活,PD模型对照组4个月时存活27只(27/30只),PD模型干预组4个月时存活28只(28/30只);(2)PD模型对照组、PD模型干预组小鼠每次注射MPTP后,先有短暂兴奋(持续7.61±2.17min),表现为四处窜跳;随即出现全身中重度震颤,皮毛及尾巴时有竖立,活动减少,持续24.23±3.89min后震颤消失;随后出现活动减少;(3)黑质纹状体区α-syn免疫荧光双染检测;(3)PD模型对照组较正常对照组明显增多,PD模型干预组较PD模型对照组有所减少,但仍较正常对照组增多;(4)Western blotting检测α-syn蛋白量的表达,正常对照组与PD模型对照组比较,P0.001;与PD模型干预组比较,P0.001;PD模型对照组与PD模型干预组比较,P0.05。结论 "抗帕颗粒"对PD小鼠黑质纹状体区α-syn异常聚集具有一定程度的抑制作用,阻断氧化应激反应可能是这种保护作用的关键机制,有望改善PD治疗现状并在临床进一步推广应用。     

帕金森病大鼠胃肠功能障碍的机制

目的 探讨6-羟基多巴胺(6-OHDA)诱导的SD大鼠帕金森病(PD)模型胃肠功能障碍的发生机制.方法 60只SD大鼠随机分为6-OHDA组和对照组;以6-OHDA诱导制备PD大鼠模型.4周后收集大鼠1h粪便排出量,计算粪便含水量,测定餐后2 h大鼠胃内固体食物残留率.采用免疫组化法检测黑质酪氨酸羟化酶(TH)、胃肠神经丛α-突触核蛋白(α-syn)、神经元型一氧化氮合酶(nNOS)的表达;应用逆转录(RT)-PCR方法检测胃、结肠组织nNOS mRNA的表达.结果 与对照组相比,6-OHDA组大鼠1 h粪便排出量及含水量明显降低,胃内固体食物残留率明显增加(均P<0.01);损伤侧黑质TH阳性细胞明显减少(P<0.01);胃肠肌间神经丛α-syn表达明显升高,nNOS表达明显降低(均P<0.01);胃肠组织nNOS mRNA表达明显降低(均P<0.01).结论 PD大鼠胃肠功能障碍可能与胃肠神经系统nNOS水平降低有关.     

TauN368和磷酸化α-synuclein在3种帕金森病动物模型脑区的表达

目的探讨3种不同帕金森病(Parkinson disease,PD)动物模型黑质、纹状体和海马中磷酸化α-synuclein(S129)[以下简称为p-α-syn(S129)]和天冬酰胺内切酶(asparagine endopeptidase,AEP)特异性切割产生的tauN368片段的表达水平。方法建立慢性1-甲基-4-苯基-1,2,3,6-四羟吡啶(MPTP)诱导的PD小鼠模型(n=10)、鱼藤酮诱导的小鼠PD模型(n=10)以及鱼藤酮诱导的大鼠PD模型(n=10)共3种模型,每种模型均设立对照组(n=10)。采用酪氨酸羟化酶(tyrosine hydroxylase,TH)免疫染色评估不同PD动物模型黑质多巴胺能神经元损伤情况,采用Western blot方法检测各组动物中脑黑质、纹状体、海马p-α-syn(S129)和tauN368的表达。结果 3种PD动物模型中脑黑质致密部TH阳性神经元数目均较对照组明显减少,提示造模成功。Western blot检测结果显示,MPTP诱导的小鼠PD模型黑质、纹状体及海马tauN368表达均较对照组升高(P0.05),黑质和海马p-α-syn(S129)表达无统计学差异(P0.05);鱼藤酮诱导的小鼠PD模型黑质及纹状体p-α-syn(S129)和tauN368表达均较对照组增加(P0.05),而海马p-α-syn(S129)和tauN368表达与对照组比较均未见统计学变化(P0.05);鱼藤酮诱导的大鼠PD模型黑质、纹状体及海马p-α-syn (S129)表达较对照组增加(P0.05),而黑质和海马tauN368的表达无统计学差异(P0.05)。结论鱼藤酮诱导的小鼠PD模型黑质和纹状体同时存在tauN368和p-α-syn(S129)的差异性表达,提示该模型可能是研究PD发病中tauN368和α-synuclein相互作用机制的理想动物模型。     

丁基苯酞对帕金森模型小鼠中脑黑质多巴胺能神经元数及TH、TNF-α蛋白表达的影响

目的研究丁基苯酞(dl-3n-butylphthalide,NBP)对由MPTP诱导的C57BL/6小鼠帕金森模型中脑黑质多巴胺能神经元数及TH、TNF-α蛋白表达的影响,进一步探讨其保护机制。方法 24只C57BL/6小鼠,随机分成3组:正常对照组,MPTP组,NBP治疗组。MPTP腹腔注射法制备帕金森模型,免疫组织化学法观察中脑黑质TH阳性神经元细胞数,蛋白质印迹法观察中脑黑质TH、TNF-α蛋白含量的变化。结果 (1)与正常对照组比较,MPTP组可见帕金森病小鼠中脑黑质TH阳性神经元明显减少(P0.01);与MPTP组比较,NBP治疗组帕金森病小鼠中脑黑质TH阳性神经元数目明显增加(P0.01);(2)与正常对照组比较,MPTP组帕金森病模型小鼠中脑黑质TH蛋白表达减少(P0.01),而TNF-α蛋白表达增加(P0.05);(3)与MPTP组比较,NBP治疗组帕金森病模型小鼠中脑黑质TH蛋白表达明显增加(P0.01),而TNF-α蛋白表达减少(P0.05)。结论丁基苯酞可能通过提高中脑黑质中TH的含量及减少TNF-α炎性介质表达发挥对MPTP所致C57BL/6小鼠帕金森模型的神经元保护作用。     

Authentically phosphorylated α-synuclein at Ser129 accelerates neurodegeneration in a rat model of familial Parkinson's disease

Parkinson's disease (PD) is characterized by the loss of dopaminergic neurons in the substantia nigra (SN) and the appearance of fibrillar aggregates of insoluble α-synuclein (α-syn) called Lewy bodies (LBs). Approximately 90% of α-syn deposited in LBs is phosphorylated at serine 129 (Ser129). In contrast, only 4% of total α-syn is phosphorylated in normal brain, suggesting that accumulation of Ser129-phosphorylated α-syn is involved in the pathogenesis of PD. However, the role of Ser129 phosphorylation in α-syn neurotoxicity remains unclear. In this study, we coexpressed familial PD-linked A53T α-syn and G-protein-coupled receptor kinase 6 (GRK6) in the rat SN pars compacta using recombinant adeno-associated virus 2. Coexpression of these proteins yielded abundant Ser129-phosphorylated α-syn and significantly exacerbated degeneration of dopaminergic neurons when compared with coexpression of A53T α-syn and GFP. Immunohistochemical analysis revealed that Ser129-phosphorylated α-syn was preferentially distributed to swollen neurites. However, biochemical analysis showed that the increased expression of Ser129-phosphorylated α-syn did not promote accumulation of detergent-insoluble α-syn. Coexpression of catalytically inactive K215R mutant GRK6 failed to accelerate A53T α-syn-induced degeneration. Furthermore, introducing a phosphorylation-incompetent mutation, S129A, into A53T α-syn did not alter the pace of degeneration, even when GRK6 was coexpressed. Our study demonstrates that authentically Ser129-phosphorylated α-syn accelerates A53T α-syn neurotoxicity without the formation of detergent-insoluble α-syn, and suggests that the degenerative process could be constrained by inhibiting the kinase that phosphorylates α-syn at Ser129.     

Paradoxical sleep deprivation modulates tyrosine hydroxylase expression in the nigrostriatal pathway and attenuates motor deficits induced by dopaminergic depletion

The nigrostriatal pathway is very likely involved in sleep regulation, considering the occurrence and high prevalence of sleep-related disorders in patients with Parkinson's disease. Indeed, dopaminergic neurons in the ventral tegmental area were recently shown to fire in bursts during paradoxical sleep (PS), but little is known about the activity of the nigrostriatal dopamine (DA) cells in relation to PS. In view of that we hypothesized that paradoxical sleep deprivation (PSD) may play a relevant role in nigrostriatal tyrosine hydroxylase (TH) expression and, subsequently, in sleep rebound. The present study was designed to determine the effects of PSD in the nigrostriatal pathway in mice by means of neurochemical and behavioral approaches. Intraperitoneal reserpine (1 mg/kg) associated to α-methyl-p-tyrosine (αMT) (250 mg/kg) to produce catecholamine depletion, or rotenone (10 mg/kg) to increase striatal DA turnover were injected 30 min before the 24 h of PSD. Catalepsy and open-field tests indicated that motor deficits induced by reserpine-αMT were counteracted by PSD, which, in contrast, potentiated the motor impairment induced by rotenone. Besides, PSD produced down-regulation on TH expression within the substantia nigra pars compacta and striatum, without affecting the number or the optical density of dopaminergic neurons present in the respective areas. Interestingly, PSD potentiated the downregulation of TH expression in the substantia nigra pars compacta and striatum induced by the co-administration of reserpine-αMT. These results reinforce the notion of a strong participation of DA in PS, as a consequence of the modulation of TH protein expression in the nigrostriatal pathway.     

Dose-related biphasic effect of the Parkinson’s disease neurotoxin MPTP,on the spread,accumulation, and toxicity of α-synuclein

BackgroundParkinson’s disease (PD), the second most common progressive neurodegenerative disorder, is characterized by the abnormal accumulation of intraneuronal inclusions enriched in aggregated α-synuclein (α-syn), known as Lewy bodies (LBs) and Lewy neurites (LNs), and significant loss of dopaminergic (DA) neurons in the substantia nigra pars compacta (SNpc) of the brain. Recent evidence suggests that the intrastriatal inoculation of α-syn preformed fibrils (PFF) in mice brain triggers endogenous α-syn in interconnected brain regions. 1-methyl, 4-phenyl, 1,2,3,6 tetrahydropyridine (MPTP), a mitochondrial neurotoxin, has been used previously to generate a PD mouse model. However, the common methods of MPTP exposure do not induce LB or α-syn aggregation in mice. In the present study, we evaluated the effect of different doses of MPTP (10 mg/kg.b.wt and/or 25 mg/kg.b.wt) on the spread, accumulation, and toxicity of endogenous α-syn in mice administered an intrastriatal injection of human α-syn PFF.MethodsWe inoculated human WT α-syn PFF in mouse striatum. At 6 weeks post PFF injection, we challenged the animal with two different doses of MPTP (10 mg/kg.b.wt and 25 mg/kg.b.wt) once daily for five consecutive days. At 2 weeks from the start of the MPTP regimen, we collected the mice brain and performed immunohistochemical analysis, and Rotarod test to assess motor coordination and muscle strength before and after MPTP injection.ResultsA single injection of human WT α-syn PFF in the mice striatum induced the propagation of α-syn, occurring as phosphorylated α-synuclein (pS129), towards the SNpc, within a very short time. Injection of a low dose of MPTP (10 mg/kg.b.wt) at 6 weeks post α-syn PFF inoculation further enhanced the spread, whereas a high dose of MPTP (25 mg/kg.b.wt.) reduced the spread. Majority of the accumulated α-syn were proteinase K resistant, as recognized using a conformation-specific α-syn antibody. Injection of α-syn PFF alone caused 12 % reduction in the number of tyrosine hydroxylase positive neurons while α-syn PFF + a low dose of MPTP caused 33 % reduction (loss), compared to the control mice injected with saline. This combination also reduced the motor coordination. Interestingly, a low dose of MPTP alone did not cause any significant reduction in the number of tyrosine hydroxylase positive neurons compared to saline treatment. Animals that received α-syn PFF and a high dose of MPTP showed massive activation of glial cells and decreased spread of α-syn, majority of which were detected in the nucleus.ConclusionOur results suggest that a combination of human WT α-syn PFF and a low dose of MPTP increases the pathological conversion and propagation of endogenous α-syn, and neurodegeneration, within a very short time. Our model can be used to study the mechanisms of α-syn propagation and screen for potential drugs against PD.     

姜黄素对帕金森病小鼠模型黑质多巴胺能神经元损伤的保护作用

目的研究姜黄素对由MPTP诱发的帕金森病小鼠模型的脑保护作用及其可能机制。方法应用免疫组织化学染色法和蛋白质印迹法(Western blotting)分别观察姜黄素干预前后帕金森病小鼠中脑黑质-纹状体系统中酪氨酸羟化酶、胶质纤维酸性蛋白阳性神经元数目的变化,以及酪氨酸羟化酶、诱导型一氧化氮合酶和胶质纤维酸性蛋白表达水平的变化。结果MPTP组小鼠中脑黑质酪氨酸羟化酶和胶质纤维酸性蛋白阳性神经元数目明显减少,与正常对照组及治疗组相比差异有统计学意义(均P<0.05)。经不同剂量(5mg/kg、50mg/kg和150mg/kg)的姜黄素干预治疗后,小鼠中脑纹状体中的酪氨酸羟化酶蛋白表达水平(相对灰度值)明显升高,而黑质中诱导型一氧化氮合酶和胶质纤维酸性蛋白表达水平明显降低,与MPTP组比较差异均有统计学意义(P<0.05);MPTP组与溶剂对照组(MPTP DMSO)之间差异无统计学意义(P>0.05)。结论姜黄素可以有效地拮抗MPTP诱导的帕金森病小鼠模型黑质多巴胺能神经元的丢失,其机制可能与姜黄素降低黑质多巴胺能神经元活性氧含量以及抑制炎症反应等作用有关。     

Rasagiline is neuroprotective in a transgenic model of multiple system atrophy

Rasagiline is a novel selective irreversible monoamine oxidase-B (MAO-B) inhibitor recently introduced for the symptomatic treatment of Parkinson disease. Like other propargylamines rasagiline has also shown neuroprotective effects independent of MAO-B-inhibition in various in vitro and in vivo models. The present study was performed to test the potential of rasagiline as a disease-modifying agent in multiple system atrophy (MSA) using a transgenic mouse model previously described by our group. (PLP)-alpha-synuclein transgenic mice featuring glial cytoplasmic inclusion pathology underwent 3-nitropropionic acid intoxication to model full-blown MSA-like neurodegeneration. Two doses of rasagiline were used (0.8 and 2.5 mg/kg) for a treatment period of 4 weeks. Rasagiline-treated animals were compared to placebo saline-treated mice by evaluation of motor behaviour and neuropathology. Motor behavioural tests including pole test, stride length test and general motor score evaluation showed improvements in motor deficits associated with 2.5 mg/kg rasagiline therapy. Immunohistochemistry and histology showed significant reduction of 3-NP-induced neuronal loss in striatum, substantia nigra pars compacta, cerebellar cortex, pontine nuclei and inferior olives of MSA mice receiving 2.5 mg/kg rasagiline. The results of the study indicate that rasagiline confers neuroprotection in a transgenic mouse model of MSA and may therefore be considered a promising disease-modifying candidate for human MSA.     

Allopregnanolone increases the number of dopaminergic neurons in substantia nigra of a triple transgenic mouse model of Alzheimer's disease

More than a third of Alzheimer's disease (AD) patients show nigrostriatal pathway disturbances, resulting in akinesia (inability to initiate movement) and bradykinesia (slowness of movement). The high prevalence of this dysfunction of dopaminergic neuron in the nigrostriatal pathway in AD suggests that the risk factors for AD appear also significant risk factors for substantia nigra pars compacta (SNpc) lesions. Previously, we have demonstrated that allopregnanolone (APα) promotes neurogenesis and improves the cognitive function in a triple transgenic mouse model of AD (3xTgAD). In this study, we sought to exam 1) the SNpc lesions in 3xTgAD mice and 2) the impact of APα on promoting the regeneration of new dopaminergic neurons in SNpc of the 3xTgAD mice. The number of Nissl-stained total neurons, tyrosine hydroxylase (TH) positive neurons, and BrdU/TH double positive newly formed neurons were analyzed with unbiased stereology. In the SNpc of 3xTgAD mice, TH positive neurons was 47+- 18 % (p = 0.007), total neurons was 62 +-11.6 % (p = 0.016), of those in the SNpc of non-Tg mice, respectively. APα treatment increased the TH positive neurons in the SNpc of 3xTgAD mice to 93.2 +- 18.5 (p = 0.021 vs. 3xTgAD vehicle) and the total neurons to 84.9+- 6.6 (p = 0.046 vs. 3xTgAD vehicle) of non-Tg mice. These findings indicate that there is a loss of neurons, specifically the TH positive neurons in SNpc of 3xTgAD mice, and that APα reverses the lesion in SNpc of 3xTgAD by increasing the formation of new TH neurons.     

Hypoxic stress accelerates the propagation of pathological alpha-synuclein and degeneration of dopaminergic neurons

Aims

The etiology of Parkinson's disease (PD) is complex and the mechanism is unclear. It has become a top priority to find common factors that induce and affect PD pathology. We explored the key role of hypoxia in promoting the pathological propagation of α-synuclein (α-syn) and the progression of PD.

Methods

We performed PD modeling by conducting intracranial stereotaxic surgery in the unilateral striatum of mice. We then measured protein aggregation in vitro. The rotarod and pole tests were employed next to measure the damage of the phenotype. Pathological deposition and autophagy were also observed by immunofluorescence staining and protein levels measured by western blotting.

Results

We demonstrated that short-term hypoxia activated phosphorylated (p)-α-syn in mice. We confirmed that p-α-syn was more readily formed aggregates than α-syn in vitro. Furthermore, we found that hypoxia promoted the activation and propagation of endogenous α-syn, contributing to the earlier degeneration of dopaminergic neurons in the substantia nigra and the deposition of p-α-syn in our animal model. Finally, autophagy inhibition contributed to the above pathologies.

Conclusion

Hypoxia was shown to accelerate the pathological progression and damage phenotype in PD model mice. The results provided a promising research target for determining common interventions for PD in the future.     

Downregulation of tyrosine hydroxylase phenotype after AAV injection above substantia nigra: Caution in experimental models of Parkinson’s disease

Adeno-associated virus (AAV) vector-mediated delivery of human α-synuclein (α-syn) gene in rat substantia nigra (SN) results in increased expression of α-syn protein in the SN and striatum which can progressively degenerate dopaminergic neurons. Therefore, this model is thought to recapitulate the neurodegeneration in Parkinson's disease. Here, using AAV to deliver α-syn above the SN in male and female rats resulted in clear expression of human α-syn in the SN and striatum. The protein was associated with moderate behavioral deficits and some loss of tyrosine hydroxylase (TH) in the nigrostriatal areas. However, the immunohistochemistry results were highly variable and showed little to no correlation with behavior and the amount of α-syn present. Expression of green fluorescent protein (GFP) was used as a control to monitor gene delivery and expression efficacy. AAV-GFP resulted in a similar or greater TH loss compared to AAV-α-syn and therefore an additional vector that does not express a protein was tested. Vectors with double-floxed inverse open reading frame (DIO ORF) encoding fluorescent proteins that generate RNA that is not translated also resulted in TH downregulation in the SN but showed no significant behavioral deficits. These results demonstrate that although expression of wild-type human α-syn can cause neurodegeneration, the variability and lack of correlation with outcome measures are drawbacks with the model. Furthermore, design and control selection should be considered carefully because of conflicting conclusions due to AAV downregulation of TH, and we recommend caution with having highly regulated TH as the only marker for the dopamine system.     

漆黄素对帕金森病小鼠模型的保护作用及机制研究

目的 探讨漆黄素对帕金森病的神经保护作用及具体机制。方法 采用MPTP腹腔注射复制亚急性PD小鼠模型，漆黄素灌胃给药，实验分为3组：control组、MPTP组、漆黄素+MPTP组。通过旷场实验、爬杆实验、悬挂实验等行为学指标评估小鼠的运动行为。采用Western blotting和免疫荧光技术检测纹状体中TH水平和黑质中TH阳性神经元数量。采用尼氏染色检测黑质区神经元的损伤状况。通过检测纹状体区GSH、SOD、T-AOC、MDA含量，评估脑组织中氧化应激水平。结果 与MPTP组相比，漆黄素+MPTP组，小鼠的运动总距离及运动速度提高（P<0.05）；爬杆总时间及转头时间缩短（P<0.05）。悬挂实验评分提高（P<0.05）。尼氏染色结果发现，漆黄素可缓解MPTP小鼠黑质区神经元损伤（P<0.05）。TH免疫印迹及免疫荧光实验发现漆黄素可改善MPTP诱导的小鼠TH表达量水平下降及阳性神经元丢失（P<0.05）。同时，漆黄素处理后，提高了MPTP小鼠GSH、SOD、T-AOC水平，降低了MPTP小鼠MDA的含量（P<0.05）。结论 漆黄素能有效改善帕金森病模型小鼠的运动功能，缓解黑质－纹状体多巴胺能神经元损伤，其机制可能与漆黄素的抗氧化作用有关。