6-羟基多巴的细胞毒作用与谷氨酸转运的关系

目的探讨6-羟基多巴(6-OHDA)导致细胞毒性与谷氨酸(glutamate,Glu)递质水平和谷氨酸转运体的相关性。方法大鼠脑黑质内定位注射6-OHDA,制备帕金森病(Parkinson's disease,PD)动物模型;用在体微透析技术收集大鼠纹状体细胞外液;用高效液相色谱法测定PD大鼠纹状体和PC12细胞的细胞外液中Glu的水平;用流式细胞仪和酶标仪检测细胞凋亡率和细胞活性;通过测定L-［³H］-Glu的摄取能力确定谷氨酸转运体的功能。结果6-OHDA诱导PC12细胞和大鼠损毁侧纹状体释放Glu增加,使PC12细胞凋亡和活性降低,而PC12细胞和突触体上的谷氨酸转运体功能显著下降。结论6-OHDA引起的神经毒性与其增加Glu释放和降低谷氨酸转运体功能有关。     

Ⅱ、Ⅲ组亲代型谷氨酸受体激动剂对6-羟基多巴诱导的PC12细胞毒性无保护作用

阐明Ⅱ、Ⅲ组亲代谢型谷氨酸受体(metabotropic glutamate receptors,mGluRs)激动剂对6—羟基多巴(6-hydroxydopamine,6-OHDA)诱导的PC12细胞毒性是否具有保护作用。方法：应用高效液相色谱仪联用荧光检测技术测定谷氨酸浓度，应用四甲基偶氮唑盐(MTT)比色法测定PC12细胞活性。结果：6—OHDA剂量依赖性地诱导PC12细胞释放谷氨酸、减低细胞活性，Ⅱ组mGluRs激动剂DCG—IV和Ⅲ组mGluRs激动剂L-AP4对6—0HDA诱导的PC12细胞释放谷氨酸和细胞活性的降低均无显影响。结论：6—OHDA对多巴胺神经元的损伤作用与其诱导谷氨酸过度释放及其继发的兴奋性神经毒性有关，Ⅱ、Ⅲ组亲代谢型谷氨酸受体激动剂对6—OHDA诱导的PC12细胞毒性无保护作用。     

迷迭香酸对谷氨酸诱导的PC12细胞损伤的效应

目的探讨迷迭香酸(rosmarinicacid,RosA)对谷氨酸(glutamate,Glu)诱导PC12细胞损伤的作用和机制。方法以谷氨酸损伤PC12细胞为模型,用甲氮甲唑蓝(MTT)法检测细胞存活状况,碘化丙啶(propidiumiodide,PI)染色流式细胞术检测细胞凋亡,RTPCR检测bclxl和bax基因的表达。结果用不同剂量谷氨酸(1、5、10、12.5、15、20mmol·L-1)孵育细胞24h后,细胞活性随药物浓度的增加依次下降,RosA(100μmol·L-1)预处理1h后可以改善PC12细胞的存活率,存活率由55.65%±5.07%增加到63.74%±2.04%;使PC12细胞的凋亡率由21.11%降至3.24%,并且使bclxl基因表达上调和bax基因表达下调。结论迷迭香酸有抗谷氨酸诱导PC12细胞凋亡的作用,其机制可能与调节bclxl和bax基因的表达有关。     

兴奋性氨基酸对海马神经干细胞损伤作用的研究

目的:通过不同浓度谷氨酸对海马神经干细胞的致伤作用及其相关机制的研究,揭示兴奋氨基酸对神经发生的作用,为多种神经缺失性病变的修复提供可靠的实验依据.方法:取孕16d胎鼠神经干细胞培养,分为正常对照组、Glu高浓度组和Glu低浓度组.台盼蓝检测细胞死亡率,全细胞膜片钳记录.结果:100μmol/L Glu干预24h后有30％神经干细胞死亡,300μmol/L Glu干预24h后有70％的神经干细胞死亡.300μmol/L Glu干预24h后可诱导(1000.25±104.67)pA内向电流与正常对照组和100μmol/L Glu干预24h后相比有显著差异(P＜0.01).结论:随着谷氨酸浓度的增加,神经干细胞死亡率增加,同时细胞内向电流增大,可能是其死亡率增加的原因之一.     

天麻素通过抑制细胞凋亡保护谷氨酸诱导的PC12细胞损伤

目的：研究天麻素（Gastrodin）对谷氨酸诱导的大鼠肾上腺嗜铬细胞瘤PC12细胞损伤的影响及可能机制。方法：以谷氨酸建立体外培养PC12细胞损伤模型并采用MTT比色法测定细胞存活率;AO/EB双染法经荧光显微镜观察细胞凋亡形态;采用流式细胞术检测细胞内活性氧含量以及Annexin V/PI染色后的细胞凋亡率;Western blot法检测细胞内Caspase-3蛋白表达。结果：天麻素可明显抑制谷氨酸诱导的PC12细胞凋亡,在0.1～10μmol/L剂量呈一定的量效关系;同时,天麻素可明显抑制谷氨酸引起的活性氧（ROS）的累积,降低谷氨酸诱导的活性Caspase-3蛋白的表达,降低PC12细胞的凋亡率,在0.1～10μmol/L剂量呈量效相关性。结论：在一定剂量范围内,天麻素对谷氨酸损伤的PC12细胞具有保护作用,其机制可能与减少ROS的生成,阻止氧化损伤的发生,抑制Caspase-3途径依赖的细胞凋亡相关。     

藁本内酯对谷氨酸诱导的PC12细胞凋亡的保护作用

研究藁本内酯对谷氨酸诱导PC12细胞凋亡的保护作用。采用MTT比色法检测细胞存活率;Annexin V-FITC/propidium iodide(PI)双染法流式细胞术(flow cytometry,FCM)检测细胞凋亡率;Fluo-3/AM荧光染色法检测钙离子含量;Western blot法检测线粒体和胞浆中细胞色素C(cytochrome C,Cyt C)及凋亡相关蛋白Caspase-3、Bcl-2、Bax的表达。结果显示,谷氨酸具有细胞毒性,其半数抑制浓度(IC50)为15 mmol·L-1;不同浓度藁本内酯(1、5、15μmol·L-1)预处理可显著提高细胞存活率。与正常对照组相比,谷氨酸单独给药组的细胞凋亡率为13.39%;藁本内酯给药组(1、5、15μmol·L-1)使细胞的凋亡率分别减少到9.06%、6.48%和3.82%。并且藁本内酯可以显著减少谷氨酸所致的钙离子内流,Western blot结果显示,藁本内酯可能通过减少线粒体Cyt C的释放,抑制Caspase-3活性,同时升高Bcl-2/Bax比值来保护谷氨酸诱导的PC12细胞凋亡。结果表明,藁本内酯对谷氨酸诱导PC12细胞的凋亡具有保护作用。该保护作用可能与抑制细胞内钙离子内流及阻断Cyt C从线粒体释放入胞浆有关。     

类叶升麻苷对谷氨酸损伤PC12细胞的保护作用

目的研究类叶升麻苷对谷氨酸诱导的PC12细胞损伤的影响。方法将PC12细胞分为正常对照组、模型对照组、阳性药组和类叶升麻苷给药组。除正常对照组外,其余各组均以1.5 mmol·L-1谷氨酸处理24 h,再分别以10μmol·L-1维生素E和15.625,31.25,62.5,125,250μmol·L-1类叶升麻苷作用。通过倒置显微镜观察细胞形态,采用四甲基偶氮唑盐(MTT)比色法检测细胞存活率,酶标法试剂盒测定乳酸脱氢酶(LDH)活性,硫代巴比妥酸(TBA)法试剂盒测定丙二醛(MDA)含量,WST[2-(4-碘苯基)-3-(4-硝基苯基)-5-(2,4-二磺酸苯基)-2氢-四唑盐,二钠盐]法试剂盒测定超氧化物歧化酶(SOD)活性,酶联免疫吸附法(ELISA)检测胞内活性氧(ROS)含量。结果与模型对照组比较,除类叶升麻苷Ⅰ组(15.625μmol·L-1AS)以外,其余各类叶升麻苷给药组均可明显改善PC12细胞形态,提高细胞存活率和SOD酶活性(P<0.01),抑制LDH活性及MDA和ROS生成(P<0.01或P<0.01)。结论类叶升麻苷对谷氨酸诱导的PC12细胞损伤具有保护作用。     

硫化氢抑制葡萄糖调节蛋白78减轻6-OHDA诱导的PC12细胞损伤

目的：探讨硫化氢（H2S）是否通过改变葡萄糖调节蛋白78（GRP78）的表达参与其对抗6-羟基多巴胺（6-OHDA）诱导PC12细胞损伤的保护作用。方法应用具有神经毒性的6-OHDA损伤PC12细胞为帕金森病细胞模型,以硫氢化钠（NaHS）作为H2S的供体;应用CCK-8比色法检测细胞存活率;DFCH-DA染色检测细胞内活性氧（ROS）的水平;Rh123染色检测细胞线粒体膜电位（MMP）;Western blot检测GRP78的表达。结果200μmol/L的6-OHDA引起PC12细胞的存活率显著降低,ROS生成增加及MMP降低,且诱导了GRP78的高表达。应用25~400μmol/L的NaHS预处理30 min,呈浓度依赖性抑制6-OHDA引起的细胞存活率降低,其中400μmol/L的NaHS作用最明显,此浓度也可以显著减少6-OHDA引起的ROS增多,提高MMP,同时明显抑制6-OHDA诱导的GRP78高表达。结论 H2S具有抗6-OHDA氧化应激损伤的PC12细胞保护作用,抑制内质网应激分子GRP78的表达可能是其机制之一。     

IL-1β在溴氰菊酯诱发谷氨酸释放中的作用

目的 探讨IL-1β与Glu在溴氰菊酯(DM)神经毒性中的关系.方法 分离雄性SD大鼠皮层、海马和下丘脑,消化成单细胞悬液置37℃培养,3个脑区的细胞均分为对照组:给予体积分数为0.1%DMSO;DM组:给予2 × 10-6mol/L DM;DM1组:给予2×10-6 mol/L DM同时加10 μmol/L IL-1β转化酶抑制剂Ac-YVAD-CHO;DM2组:给予2×106 mol/L DM后15 min加10 μmol/L Ac-YVAD-CHO;DM3组:给予2×10-6 mol/L DM 同时加15 μmol/L Ac-YVAD-CHO;DM4组:给予2×10-6 mol/L DM后15 min加15 μmol/L Ac-YVAD-CHO,每组3个平行样,DM作用1 h后收集培养上清,高效液相色谱(HPLC)法测上清中Glu释放量.结果 DM可显著促进皮层和海马神经细胞的Glu释放,但抑制下丘脑细胞Glu释放;皮层和海马各抑制剂组Glu的释放均显著低于DM组但仍高于对照组,DM作用后15 min给予10 μmol/L,Ac-YVAD-CHO对皮层细胞的Glu释放的抑制作用较先给予同等剂量的抑制剂作用强(P<0.01);对海马神经细胞,15 μmol/L抑制剂对DM诱导Glu释放的抑制作用较10 μmol/L抑制剂作用强,DM作用后15 min再给予15 μmol/L较先给予15 μmol/L抑制剂的抑制作用强;而Ac-YVAD-CHO对DM诱导下丘脑细胞谷氨酸(Glu)释放的抑制作用各抑制组间无差别.结论 IL-1β促进了DM对皮层和海马神经细胞Glu的诱导作用.     

3＇-大豆苷元磺酸钠抗谷氨酸引起的PC12细胞损伤的研究

目的探讨3＇-大豆苷元磺酸钠抗谷氨酸引起的PC12细胞损伤的影响。方法采用谷氨酸诱导PC12细胞损伤模型,分别给予3.0、10.0μmol/ml的3＇-大豆苷元磺酸钠干预,采用MTT法检测PC12细胞活力;同时测定培养液中乳酸脱氢酶活性、超氧化物歧化酶活性和丙二醛的含量。结果3.0、10.0μmol/ml的3＇-大豆苷元磺酸钠能提高谷氨酸引起的PC12细胞的存活率;3.0、10.0μmol/ml的3＇-大豆苷元磺酸钠能抑制由谷氨酸引起的乳酸脱氢酶活性;3.0、10.0μmol/ml的3＇-大豆苷元磺酸钠能提高超氧化物歧化酶活性和降低丙二醛含量。结论3＇-大豆苷元磺酸钠对谷氨酸引起的PC12细胞损伤具有明显的保护作用,其保护作用可能与抑制由谷氨酸引起的乳酸脱氢酶活性,提高超氧化物歧化酶活性和降低丙二醛含量有关。     

IGF-1对6-OHDA诱导神经元氧化损伤的保护作用

目的 探讨胰岛素样生长因子-1（IGF-1）对6-羟基多巴胺（6-OHDA）诱导的PC12细胞氧化损伤的保护作用。方法 以25、50、100、150、200 μmol/L 的6-OHDA 处理PC12细胞,在12、24、48 h用MTT 法检测6-OHDA 对PC12细胞活性的影响,筛选最佳的实验浓度和观察时间。实验分为3组：对照组、6-OHDA组（150 μmol/L处理24 h）和IGF-1+6-OHDA组（IGF-1 100 nmol/L预处理2 h,后加入150 μmol/L 6-OHDA处理24 h）,MTT法检测各组细胞活性;免疫荧光染色法检测细胞活性氧（ROS）水平;Hoechst33342/PI双染法检测细胞凋亡。结果 随6-OHDA浓度的增加和作用时间的延长,PC12细胞的活性呈梯度降低,150 μmol/L 6-OHDA浓度和处理后24 h作为本研究的最佳的实验浓度和观察时间。与6-OHDA组比较,IGF-1+6-OHDA组PC12细胞活力增强、ROS水平下降、细胞凋亡减少。结论 IGF-1预处理能减少6-OHDA引起的PC12细胞氧化损伤及凋亡,增加细胞活性,为防治帕金森病提供了潜在的治疗策略。     

Parkin represses 6-hydroxydopamine-induced apoptosis via stabilizing scaffold protein p62 in PC12 cells

Aim:

Parkin has been shown to exert protective effects against 6-hydroxydopamine (6-OHDA)-induced neurotoxicity in different models of Parkinson disease. In the present study we investigated the molecular mechanisms underlying the neuroprotective action of parkin in vitro.

Methods:

HEK293, HeLa and PC12 cells were transfected with parkin, parkin mutants, p62 or si-p62. Protein expression and ubiquitination were assessed using immunoblot analysis. Immunoprecipitation assay was performed to identify the interaction between parkin and scaffold protein p62. PC12 and SH-SY5Y cells were treated with 6-OHDA (200 μmol/L), and cell apoptosis was detected using PI and Hoechst staining.

Results:

In HEK293 cells co-transfected with parkin and p62, parkin was co-immunoprecipitated with p62, and parkin overexpression increased p62 protein levels. In parkin-deficient HeLa cells, transfection with wild-type pakin, but not with ligase activity-deficient pakin mutants, significantly increased p62 levels, suggesting that parkin stabilized p62 through its E3 ligase activity. Transfection with parkin or p62 significantly repressed ERK1/2 phosphorylation in HeLa cells, but transfection with parkin did not repress ERK1/2 phosphorylation in p62-knockdown HeLa cells, suggesting that p62 was involved in parkin-induced inhibition on ERK1/2 phosphorylation. Overexpression of parkin or p62 significantly repressed 6-OHDA-induced ERK1/2 phosphorylation in PC12 cells, and parkin overexpression inhibited 6-OHDA-induced apoptosis in PC12 and SH-SY5Y cells.

Conclusion:

Parkin protects PC12 cells against 6-OHDA-induced apoptosis via ubiquitinating and stabilizing scaffold protein p62, and repressing ERK1/2 activation.     

芍药苷对6羟基多巴胺致PC12细胞损伤的保护作用

目的:探讨芍药苷对6羟基多巴胺(6-OHDA)致大鼠肾上腺嗜铬细胞瘤细胞(PC12)的细胞损伤保护作用及其可能机制.方法:体外培养PC12细胞,用6-OHDA建立细胞损伤模型.MTT和乳酸脱氢酶(LDH)活性测定存活率;RT-PCR检测Bcl-2、Bax的mRNA表达,Hochest33342/PI双染检测细胞凋亡率.结果:25、50、100 μmol·L-1芍药苷可显著减少6-OHDA诱导的PC12细胞凋亡,降低LDH漏出率,增加Bcl-2 mRNA和减少Bax mRNA表达.结论:芍药苷可显著减少6-OHDA诱导的PC12细胞凋亡,其作用机制可能与调节Bax、Bcl-2表达有关.     

木豆素A对皮质酮诱导的PC12细胞损伤的保护作用

利用皮质酮诱导PC12细胞损伤模型,研究木豆素A对皮质酮诱导的PC12细胞的保护作用并探讨相应的保护途径。采用100μmol.L1皮质酮与PC12细胞作用48 h,诱导PC12细胞损伤,然后与不同浓度的木豆素A孵育24 h。检测细胞存活率、LDH渗漏量、细胞内Ca2+浓度及caspase-3活性。结果显示,PC12细胞与皮质酮孵育48 h后细胞存活率明显降低,而LDH漏出量、细胞内Ca2+浓度及caspase-3活性均显著升高;木豆素A(4.0、8.0及16.0μmol.L1)具有改善作用,但量效关系不明显。研究表明,木豆素A对皮质酮诱导的PC12细胞损伤具有明显的保护作用,其保护作用可能是通过降低Ca2+浓度及caspase-3活性来实现的。     

Effects of 6-hydroxydopamine on mitochondrial function and glutathione status in SH-SY5Y human neuroblastoma cells.

SH-SY5Y human neuroblastoma cells were incubated with 6-hydroxydopamine (6-OHDA) for 4 and 24 h to examine the mechanism of cell death and to determine the time-dependent effects of 6-OHDA on cellular glutathione status. After 4 h, 6-OHDA significantly depleted cellular ATP and GSH concentrations with only slight increases in cell death. GSH:GSSG ratios and mitochondrial membrane potential (Deltapsim) were significantly decreased during 4 h incubations with 6-OHDA. High concentrations of 6-OHDA (100 microM) induced oxidative stress and mitochondrial dysfunction in SH-SY5Y cells within 4 h leading to cell death. In 24 h incubations, 25 and 50 microM 6-OHDA significantly decreased ATP concentrations; however, significant increases in cell death were only observed with 50 microM 6-OHDA. 6-OHDA induced a concentration-dependent increase in GSH and total glutathione concentrations after 24 h. After exposure to 50 microM 6-OHDA, GSH concentrations were increased up to 12-fold after 24 h with no change in the GSH:GSSG ratio. Gene analysis suggests that the increase in GSH concentration was due to increased expression of the GSH synthesis genes glutamate cysteine ligase modifier and catalytic subunits. Our results suggest that 6-OHDA induces oxidative stress in SH-SY5Y cells resulting in an adaptive increase in cellular GSH concentrations.     

Group I metabotropic glutamate receptors reduce excitotoxic injury and may facilitate neurogenesis

Group I metabotropic glutamate receptor (mGluR) agonist DHPG reduced nerve cell death caused by their exposure to NMDA ("neuroprotective effect") and attenuated NMDA receptor-mediated currents [Blaabjerg, M., Baskys, A., Zimmer, J., Vawter, M. P., 2003b. Changes in hippocampal gene expression after neuroprotective activation of group I metabotropic glutamate receptors. Brain Research, Molecular Brain Research 117, 196-205.]. In the present study, we used organotypic hippocampal culture preparation to examine specific phospholipase C (PLC) inhibitor U73122 effects on DHPG-induced neuroprotection, changes in excitatory synaptic transmission associated with the neuroprotective DHPG treatment and a role of group I mGluR ligands in neurogenesis. Results show that short (10 min) DHPG treatment did not result in neuroprotection but significantly depressed field synaptic potentials (fEPSP) in the Schaffer collateral-CA1 pathway. The fEPSP depression was not affected by the PLC inhibitor U73122. In contrast, prolonged (2-h) treatment of cultures with DHPG induced a significant protective effect that was blocked by a PLC inhibitor U73122 but not by its inactive analog U73343. Voltage-clamp measurements of spontaneous miniature excitatory post-synaptic currents (EPSCs) recorded in CA1 neurons from cultures treated with DHPG (10 microM, 2 h) showed a significant reduction of the EPSC amplitude in DHPG-treated but not control (untreated) cultures. This reduction was completely abolished by U73122, suggesting a PLC involvement. Since activation of PLC is thought to be associated with cell proliferation, we investigated whether group I mGluR agonist DHPG or subtype antagonists LY367385 and MPEP have an effect on dentate granule cells expressing immature neuronal marker TOAD-64. DHPG (100 microM, 72 h) slightly but not significantly increased the number of TOAD-64 positive cells. The mGluR1 antagonists LY367385 (10 microM, 72 h) markedly decreased the number of TOAD-64 positive cells and mGluR5 antagonist MPEP (1 microM, 72 h) had no effect. These data suggest that (1) prolonged activation of group I mGluRs reduces nerve cell susceptibility to excitotoxic injury in a PLC-dependent manner; (2) this reduction is associated with a PLC-dependent depression of excitatory synaptic transmission; and (3) mGluR1 activation may facilitate neurogenesis.