别孕烯醇酮对帕金森病模型小鼠黑质多巴胺能神经元的影响及可能的分子机制

目的 探讨别孕烯醇酮（APα）对帕金森病（PD）小鼠黑质-纹状体多巴胺能系统及行为学的影响及可能的分子机制。方法 90只3月龄体重为20~25 g雄性C57BL/6小鼠1侧纹状体被注射6-羟多巴胺（6-OHDA）复制小鼠PD模型,再给予APα及γ-氨基丁酸A受体（GABAAR）拮抗剂荷包牡丹碱（Bic）。采用ELISA检测血清及大脑皮质APα含量和纹状体多巴胺水平,免疫组织化学法检测黑质多巴胺能神经元及其纹状体纤维投射数量的变化,Western blotting检测中脑胞膜GABAAR、胞质及胞核各蛋白水平的变化,并通过免疫共沉淀验证它们之间的相互作用,观察小鼠行为学的变化。结果 PD小鼠大脑皮质内源性APα水平显著降低,黑质多巴胺能阳性神经元及其纹状体纤维投射含量下降,胞膜、胞质和胞核各蛋白的水平也明显下降,小鼠的运动功能发生障碍。在给予外源性APα处理后,上述情况均有所改善。但在应用Bic后,上述调控GABAAR/钙离子-钙调蛋白依赖性蛋白激酶Ⅱδ3/脑源性神经营养因子信号呈现相反的变化,免疫共沉淀结果显示,蛋白之间存在相互作用。结论 外源性的APα通过增加其内源性水平调控GABAAR/钙离子-钙调蛋白依赖性蛋白激酶Ⅱδ3/脑源性神经营养因子信号通路促进PD模型小鼠黑质-纹状体多巴胺能神经系统和小鼠行为学的改善。     

多巴胺受体在大鼠嗅球的表达及其在帕金森病大鼠嗅觉障碍中的作用

目的 观察多巴胺受体在大鼠嗅球（OB）的表达与分布,探讨左旋多巴（L-DOPA）治疗对帕金森病（PD）大鼠嗅觉的影响。 方法 采用免疫印迹、免疫荧光等方法观察多巴胺受体在大鼠OB中的表达;6-羟多巴胺（6-OHDA）双侧注射建立PD大鼠模型,检测L-DOPA治疗对PD大鼠嗅觉功能及谷氨酸脱羧酶（GAD）和脑源性神经营养因子（BNDF）表达的影响。 结果 嗅球内D1和D2两种多巴胺受体亚型表达含量高。D1和D2在颗粒细胞层（GCL）内GAD阳性的γ-氨基丁酸（GABA）能神经元上大量表达,被酪氨酸羟化酶（TH）阳性神经纤维终末包绕。PD大鼠OB内GCL层TH蛋白表达明显下降（0.05±0.01 vs 0.01±0.00,P<0.001）。L-DOPA治疗后,PD大鼠找寻食物小球时间显著降低［（624.4±113.4）s vs(312.4±79.35)s,P<0.05］,OB内BDNF表达显著升高（0.02±0.01 vs 0.07±0.01,P<0.01）。 结论 D1和D2在GCL层GABA能神经元大量表达。L-DOPA治疗可缓解PD大鼠嗅觉障碍,可能与激活OB内GABA能神经元上的D1和D2复合体,进而改善BDNF表达有关。     

山栀苷对6-羟基多巴胺损伤的SH-SY5Y细胞的保护作用及其机制

目的：观察山栀苷对6-羟基多巴胺（6-OHDA）诱导的SH-SY5Y细胞氧化损伤的作用,并探讨其作用的分子机制。方法：以6-OHDA诱导的SH-SY5Y细胞为帕金森病体外细胞模型,分别以5、50、100和200μmol/L山栀苷作用于受损细胞,另设空白组及50μmol/L栀子苷阳性对照组。CCK-8法检测细胞活力;倒置显微镜下观察细胞形态学改变;流式细胞术检测细胞内活性氧（ROS）的荧光强度;分子对接技术评价山栀苷、栀子苷与Kelch样ECH相关蛋白1(Keap1)的结合情况;Western blot检测Keap1、核因子E2相关因子2(Nrf2)和血红素加氧酶1(HO-1)蛋白表达水平;RT-qPCR检测HO-1的mRNA水平。结果：（1）与空白组比较,模型组细胞活力降低,细胞数量减少,形态改变明显,ROS水平显著升高,Nrf2和HO-1蛋白表达均显著下降,HO-1的mRNA水平显著降低（P<0.05）;(2)与模型组比较,山栀苷预处理2 h可提高6-OHDA损伤SH-SY5Y细胞的活力,其中100μmol/L山栀苷组的细胞活力最高（P<0.05）,还可显著降低ROS水平...     

胶质细胞系源性神经营养因子促进大鼠中脑多巴胺能神经元存活与分化的机制

目的探讨胶质细胞系源性神经营养因子（GDNF）促进中脑多巴胺（DA）能神经元存活和分化过程中,磷脂酰肌醇3激酶（P13K）信号通路和丝裂原活化蛋白激酶（MAPK）信号通路的可能作用.方法生后大鼠中脑脑片培养,并依培养基内加入的不同物质分为空白对照组、GDNF组、PI3K通路阻断组、MAPK通路阻断组.培养6 d后,进行酪氨酸羟化酶（TH）免疫组织化学染色,光镜观察,计算机辅助图像分析,统计学处理;同时用Western blotting方法检测脑片中TH的表达.结果GDNF组TH表达阳性神经元的形状更趋向成熟,其TH表达阳性神经元的密度、胞体大小和TH的表达水平均显著高于空白对照组;P13K通路阻断组TH表达阳性神经元几乎消失,其TH表达水平显著低于GDNF组而与空白对照组无显著差别;MAPK通路阻断组TH表达阳性神经元的密度及TH表达水平与GDNF组无显著区别,但TH表达阳性神经元胞体显著小于GDNF组.结论P13K通路参与介导GDNF对DA能神经元的促存活作用,而MAPK通路参与介导其促形态学分化作用.     

抑制miR-181a对鱼藤酮诱导的SH-SY5Y多巴胺能细胞损伤的保护作用

目的:通过抑制mi R-181a表达研究其对鱼藤酮诱导SH-SY5Y的细胞损伤、内质网应激以及未折叠蛋白反应(unfolded protein response,UPR)的影响,为mi R-181a在帕金森病治疗方面提供初步的实验依据。方法:不同浓度的鱼藤酮诱导SH-SY5Y作用12、24、48、72 h;mi R-181a类似物和mi R-181a抑制剂及0.4μmol/L鱼藤酮诱导SH-SY5Y作用24 h;采用CCK-8法检测细胞存活率;Annexin V/PI双染检测细胞凋亡;双荧光素酶报告基因检测mi R-181a与葡萄糖调节蛋白78(glucose regulated protein 78 k D,GRP78)的靶标关系;q RT-PCR检测mi R-181a和GRP78 m RNA表达水平;Western Blot检测GRP78、肌醇需酶1α(inositol-requiring enzyme 1,IRE1α)、X-盒结合蛋白1(X box-binding protein 1,XBP1)和CCAAT/增强子结合蛋白同源蛋白(CCAAT/enhancer-binding protein-homologous protein,CHOP)的蛋白表达水平。结果:(1)CCK-8结果显示:随着鱼藤酮浓度(0.1μmol/L)增加,SH-SY5Y存活率降低,并存在浓度和时间依赖性;其中0.4μmol/L作用24 h后存活率已降为0.6(P0.05),加入mi R-181a抑制剂后细胞存活率升高达0.8(P0.05);(2)Annexin V/PI双染结果显示:抑制mi R-181a表达,细胞的凋亡降低至0.23(P0.05);(3)双荧光素酶报告基因检测显示:mi R-181a与GRP78存在直接的靶标关系;(4)q RT-PCR结果显示:0.4μmol/L鱼藤酮作用24 h后细胞mi R-181a呈高表达(P0.05),抑制mi R-181a表达可上调GRP78 m RNA水平(P0.05);(5)Western Blot结果显示:抑制mi R-181a表达可上调GRP78和下调p IRE1α、XBP1和CHOP的蛋白表达(P0.05)。结论:抑制mi R-181a表达可减轻鱼藤酮诱导的SH-SY5Y细胞损伤,其机制可能通过上调GRP78进而调节内质网应激以及抑制UPR相关信号通路,从而发挥对神经元细胞的保护作用。     

精氨酸加压素对大鼠视前区GABA_A受体亚单位磷酸化的影响

目的:研究精氨酸加压素(AVP)对大鼠视前区γ-氨基丁酸(GABA)A型受体(GABA_A受体)亚单位(α、β和γ2)表达和磷酸化的影响。方法:实验分为对照组、AVP组、V1a受体抑制剂+AVP组和V1a受体抑制剂组(均n=10);腹腔注射AVP或V1a受体抑制剂0.5 h后,采用RT-qPCR和Western blot法检测视前区GABA_A受体亚单位(α、β和γ2)表达及磷酸化的变化。结果:与对照组相比,AVP或V1a受体抑制剂组大鼠视前区GABA_A受体亚单位表达均无显著变化;AVP能显著上调视前区GABA_A受体γ2亚单位的磷酸化水平(P0.05);AVP显著增加蛋白激酶C(PKC)和钙/钙调蛋白依赖性蛋白激酶Ⅱ(CaMKⅡ)表达和磷酸化(P0.01)。结论:外源性AVP不影响GABA_A受体亚单位(α、β和γ2)表达,但主要通过V1a受体激活PKC和CaMKⅡ,影响γ2亚单位磷酸化水平,从而调制视前区GABA_A受体介导的抑制性突触传递。     

激活mTORC2/Akt信号通路对6-羟基多巴胺模型小鼠多巴胺能神经元和行为学的影响

目的 探讨激活哺乳动物雷帕霉素靶蛋白复合物2(mTORC2)/Akt信号通路对6-羟基多巴胺(6-OHDA)模型小鼠多巴胺能神经元和行为学的影响及可能的机制。方法 将36只体重20～25 g 3月龄Nestin-CreER^TM::ROSA26-LacZ雄性C57BL/6J小鼠分为NS+玉米油组、6-OHDA+玉米油组、6-OHDA+PP242组、6-OHDA+A-443654组,并在小鼠右侧纹状体注射6-OHDA制备帕金森病(PD)小鼠模型以及每日腹腔注射mTORC2/Akt信号通路激动剂A-443654或抑制剂PP242。通过ELISA测定血清肿瘤坏死因子α(TNF-α)和白细胞介素1β(IL-1β)的水平;免疫组织化学和免疫荧光染色考察黑质(SN)-纹状体小胶质细胞、脑室周围神经前体细胞(NPCs)和多巴胺能神经元数目,Western blotting检测中脑水管mTORC2/Akt信号通路各相关蛋白Rictor, p-Akt和DNA损伤反应调节1(REDD1)的表达并通过免疫共沉淀验证它们之间的相互作用,最后观察各组小鼠行为学的变化。结果 6-OHDA模型小...     

核受体相关因子1基因转染骨髓源性神经干细胞体外诱导向多巴胺能神经元的分化

背景：核受体相关因子1基因修饰是否促进骨髓源性神经干细胞向多巴胺能神经元分化少见报道。 目的：观察核受体相关因子1基因修饰骨髓源性神经干细胞在体外诱导分化为多巴胺能神经元的作用。 方法：体外培养和纯化大鼠骨髓源性神经干细胞,将骨髓源性神经干细胞分为4组,将未转染的骨髓源性神经干细胞随机分为对照组,脑源性神经营养因子组;将筛选出的重组质粒转染阳性的神经干细胞分为核受体相关因子1组和核受体相关因子1+脑源性神经营养因子组。 结果与结论：RT-PCR显示转染的骨髓源性神经干细胞4 d后核受体相关因子1高表达,分化结果显示：核受体相关因子1+脑源性神经营养因子组细胞内酪氨酸羟化酶在mRNA水平上的表达量最高,神经干细胞贴壁分化后各组酪氨酸羟化酶阳性细胞比例均明显高于对照组,其中以核受体相关因子1+脑源性神经营养因子组分化比例最高,为(52.44±15.9)%。提示核受体相关因子1基因修饰可促进骨髓源性神经干细胞向多巴胺能神经元分化,并通过脑源性神经营养因子的诱导作用,在体外可获得大量的多巴胺能神经元。     

多巴胺对出血性脑卒中大鼠胶质纤维酸性蛋白和脑源性神经营养因子表达的影响及保护机制

目的：探讨多巴胺（DA）对出血性脑卒中大鼠的胶质纤维酸性蛋白（GFAP）和脑源性神经营养因子（BDNF） 表达的影响及保护机制。方法：建立出血性脑卒中大鼠模型,将大鼠随机分为假手术组、脑出血模型组（ICH 组）和DA 组（ 脑出血模型给予DA 组）。分别比较3 组大鼠的神经功能障碍评分、神经元形态、脑水肿、细胞凋 亡和脑组织形态变化;免疫组织化学染色法检测脑组织中GFAP 和BDNF 蛋白的表达。结果：与假手术组相比较, ICH 组神经功能障碍评分显著降低;与ICH 组相比,DA 组神经功能障碍评分显著升高。与假手术组比较,ICH 组尼氏小体数量显著减少;与ICH 组相比,DA 组尼氏小体数量明显增加;ICH 组脑组织含水量和细胞凋亡数量 显著高于假手术组;与ICH 组相比,DA 组脑组织含水量和细胞凋亡数量均显著降低。ICH 组脑组织出现了不同 程度的水肿,其中一部分神经细胞出现了明显肿胀,间质之间明显增宽,神经元结构受到了严重破坏,严重的 神经元出现坏死,且有大量的炎性细胞浸润;DA 组大鼠的脑组织形态得到明显的改善。与假手术组相比,ICH 组脑组织中GFAP 蛋白阳性表达显著增加,BDNF 蛋白阳性表达显著降低;与ICH 组大鼠相比,DA 组脑组织中 GFAP 阳性表达明显减少,BDNF 蛋白阳性表达明显增多。结论：DA 能抑制脑组织中GFAP 表达,促进BDNF 的 表达,改善脑出血的神经功能障碍,进而对出血性脑卒中受损脑组织起到保护作用。     

脑源性神经营养因子经由环磷酸腺苷反应元件结合蛋白磷酸化对缺氧大鼠胚脑皮质神经元细胞的保护作用

转录因子环磷酸腺苷反应元件结合蛋白(Cyclic AMP response element-binding protein,CREB)是胚脑皮质神经元细胞内脑源性神经营养因子(Brain-derived neurotrophic factor,BDNF)诱导基因表达的重要调节因子.我们前期的研究表明BDNF对缺氧性神经元损伤具有保护作用,为了阐明BDNF对缺氧性神经元损伤的保护作用是否经过了核蛋白CREB的磷酸化,本研究采用蛋白质免疫印迹法检测单纯缺氧组和BDNF干预组胚脑皮质神经元细胞内CREB及Ser133磷酸化CREB在不同时间点表达水平的变化.结果显示缺氧及BDNF均能刺激胚脑皮质神经元细胞内Ser133磷酸化CREB表达增加,在不同缺氧时间点BDNF干预组Ser133磷酸化CREB表达水平较单纯缺氧组明显增强 (P＜0.01), BDNF干预组1 h后Ser133磷酸化CREB表达至高峰,以后持续表达维持6 h以上,维持时间较单纯缺氧组明显延长;在缺氧0～3 h, BDNF干预组细胞内总CREB表达水平与单纯缺氧组基本一致;随着缺氧时间的延长,单纯缺氧组细胞内CREB表达明显减少,以第5～6 h最明显.结果表明,BDNF对缺氧性神经元损伤的保护作用经过了核蛋白CREB的磷酸化.     

Curcumin I protects the dopaminergic cell line SH-SY5Y from 6-hydroxydopamine-induced neurotoxicity through attenuation of p53-mediated apoptosis

Mesolimbic brain-derived neurotrophic factor (BDNF) is implicated in sustained behavioral changes following chronic social stress, and its depletion may reduce susceptibility to such behavioral alterations. Enhanced mesolimbic BDNF is proposed as pro-depressive and anhedonic, while depleting ventral tegmetal area (VTA) BDNF increases weight by enhancing hedonic eating. Here, we questioned whether depletion of VTA BDNF would alleviate social defeat stress-induced deficits in weight regulation, or affect social behavior in the presence or absence of social stress. Male Sprague-Dawley rats received bilateral intra-VTA infusions of adeno-associated virus (AAV) vectors containing shRNA against BDNF or a control virus. Three weeks later, rats underwent 4 episodes of social defeat stress involving exposure to an aggressive Long-Evans resident rat, or control handling every third day. Depleted VTA BDNF conferred resistance to the deficient weight regulation normally observed during intermittent social defeat stress, and enhanced long-term weight gain regardless of stress history. In addition, social approach and avoidance behavior towards a novel social target were measured 7 weeks after stress. Social defeat stress chronically reduced social behavior, whereas depletion of VTA BDNF chronically increased social behavior. Our results reveal that depletion of VTA BDNF alleviates some consequences of intermittent social defeat stress, enhances social behavior, and may contribute to weight gain. These data implicate VTA BDNF in protracted behavioral responses to stress, social stimuli, and weight regulation.     

Neuroprotective effects of tenuigenin in a SH-SY5Y cell model with 6-OHDA-induced injury

Tenuigenin, an active component of Polygala tenuifolia root extracts, has been shown to provide antioxidative and anti-aging effects in Alzheimer's disease, as well as to promote proliferation and differentiation of neural progenitor cells. However, the effects of tenuigenin on Parkinson's disease remain unclear. In the present study, SH-SY5Y cells were utilized to determine the effects of tenuigenin on 6-hydroxydopamine (6-OHDA)-induced injury. Results showed that 1.0 × 10⁻¹–10 μM tenuigenin significantly promoted cell viability and reduced cell death. In addition, tenuigenin protected mitochondrial membrane potential (MMP) against 6-OHDA damage and significantly increased glutathione and superoxide dismutase expression. At the mRNA level, tenuigenin resulted in down-regulation of caspase-3, but up-regulation of tyrosine hydroxylase expression in 6-OHDA damaged cells. These results suggested that tenuigenin provides neuroprotection to dopaminergic neurons from 6-OHDA-induced damage. The neuroprotective mechanisms might involve antioxidative effects, maintenance of mitochondrial function, and regulation of caspase-3 and tyrosine hydroxylase expression and activity. Tenuigenin could provide a novel antioxidative strategy for Parkinson's disease.     

Curcumin I protects the dopaminergic cell line SH-SY5Y from 6-hydroxydopamine-induced neurotoxicity through attenuation of p53-mediated apoptosis

Oxidative stress (OS) plays a pivotal role in the pathogenesis of Parkinson's disease (PD). 6-Hydroxydopamine (6-OHDA) is a neurotoxin used to induce oxidative cell death of dopaminergic neurons in experimental models of PD. Curcumin I, or diferuloylmethane is a pure compound isolated from Curcuma longa Linn. that has been reported to have neuroprotective properties. The precise mechanism, however, remains unclear. This study aims to elucidate the mechanisms by which curcumin I exerts its effects, using 6-OHDA-induced neurotoxicity in the human dopaminergic cell line SH-SY5Y. In our experiments, pretreatment with curcumin I improved cell viability, and significantly reduced reactive oxygen species (ROS). Further investigations revealed a reduction of p53 phosphorylation and decrease of the Bax/Bcl-2 ratio, as measured by mRNA expression and protein level. Taken together, these findings indicate that curcumin I protects dopaminergic neurons from 6-OHDA-induced toxicity via the reduction of ROS production, and subsequent attenuation of p53 phosphorylation and reduction of the Bax/Bcl-2 ratio.     

TrkB inhibition as a therapeutic target for CNS-related disorders

The interaction of brain-derived neurotrophic factor (BDNF) with its tropomyosin-related kinase receptor B (TrkB) is involved in fundamental cellular processes including neuronal proliferation, differentiation and survival as well as neurotransmitter release and synaptic plasticity. TrkB signaling has been widely associated with beneficial, trophic effects and many commonly used psychotropic drugs aim to increase BDNF levels in the brain. However, it is likely that a prolonged increased TrkB activation is observed in many pathological conditions, which may underlie the development and course of clinical symptoms. Interestingly, genetic and pharmacological studies aiming at decreasing TrkB activation in rodent models mimicking human pathology have demonstrated a promising therapeutic landscape for TrkB inhibitors in the treatment of various diseases, e.g. central nervous system (CNS) disorders and several types of cancer. Up to date, only a few selective and potent TrkB inhibitors have been developed. As such, the use of crystallography and in silico approaches to model BDNF-TrkB interaction and to generate relevant pharmacophores represent powerful tools to develop novel compounds targeting the TrkB receptor.     

Insulin signaling in the central nervous system: learning to survive

Insulin is best known for its role in peripheral glucose homeostasis. Less studied, but not less important, is its role in the central nervous system. Insulin and its receptor are located in the central nervous system and are both implicated in neuronal survival and synaptic plasticity. Interestingly, over the past few years it has become evident that the effects of insulin, on neuronal survival and synaptic plasticity, are mediated by a common signal transduction cascade, which has been identified as "the PI3K route". This route has turned out to be a major integrator of insulin signaling in the brain. A pronounced feature of this insulin-activated route is that it promotes survival by directly inactivating the pro-apoptotic machinery. Interestingly, it is this same route that is required for the induction of long-term potentiation and depression, basic processes underlying learning and memory. This leads to the hypothesis that the PI3K route forms a direct link between learning and memory and neuronal survival. The implications of this hypothesis are far reaching, since it provides an explanation why insulin has beneficial effects on learning and memory and how synaptic activity can prevent cellular degeneration. Applying this knowledge may provide novel therapeutic approaches in the treatment of neurodegenerative diseases such as Alzheimer's disease.     

Revisiting the astrocyte-oligodendrocyte relationship in the adult CNS

The lineages of both astrocytes and oligodendrocytes have been popular areas of research in the last decade. The source of these cells in the mature CNS is relevant to the study of the cellular response to CNS injury. A significant amount of evidence exists to suggest that resident precursor cells proliferate and differentiate into mature glial cells that facilitate tissue repair and recovery. Additionally, the re-entry of mature astrocytes into the cell cycle can also contribute to the pool of new astrocytes that are observed following CNS injury. In order to better understand the glial response to injury in the adult CNS we must revisit the astrocyte-oligodendrocyte relationship. Specifically, we argue that there is a common glial precursor cell from which astrocytes and oligodendrocytes differentiate and that the microenvironment surrounding the injury determines the fate of the stimulated precursor cell. Ideally, better understanding the origin of new glial cells in the injured CNS will facilitate the development of therapeutics targeted to alter the glial response in a beneficial way.     

The putative neurodegenerative links between depression and Alzheimer's disease

Alzheimer's disease (AD) is the leading neurodegenerative cause of dementia in the elderly. Thus far, there is no curative treatment for this devastating condition, thereby creating significant social and medical burdens. AD is characterized by progressive cognitive decline along with various neuropsychiatric symptoms, including depression and psychosis.