MPP+重新启动多巴胺能神经元细胞周期的作用及机制

目的研究1-甲基-4-苯基吡啶离子(MPP )重新启动多巴胺能神经元细胞周期的作用及机制。方法使用MPP 处理神经元样分化的PC12细胞,采用四甲基偶氮唑盐(MTT)法检测细胞活力,流式细胞仪检测早期凋亡细胞和细胞周期分布,免疫细胞化学检测ERK/MAPK通路活化水平。结果经MPP 处理后,细胞活力呈浓度依赖性下降,经25、50、75、100、150 mmol/L MPP 处理24 h后细胞存活率分别下降至对照组的(97.32±2.41)%(、67.69±3.03)%、(56.00±3.12)%、(47.23±2.55)%、(40.00±2.46)%,与对照组相比差异均有统计学意义(P<0.01)。经75 mmol/L MPP 处理后出现早期凋亡细胞,随处理时间延长,细胞凋亡率逐渐增加,其处理4、8、16和24 h后细胞凋亡率分别为(7.26±3.43)%、(8.34±3.55)%(、20.04±2.64)%和(28.46±2.35)%(P<0.01)。同时细胞周期中G0/G1期细胞减少,S期和G2/M期细胞增多(P<0.01),细胞内ERK1/2通路活化。结论MPP 可通过活化ERK1/2通路重新启动多巴胺神经元的细胞周期,并诱导多巴胺能神经元凋亡。     

美满霉素对帕金森病细胞凋亡模型保护作用的研究

目的探讨美满霉素(MC)对1甲基4苯基吡啶离子(MPP+)诱导的帕金森病细胞凋亡模型保护作用的机制。方法将不同浓度(10、50、250、500μmol/L)MPP+加入培养的PC12细胞中,选择最适当浓度的MPP+建立多巴胺神经元凋亡模型(MPP+组);通过四甲基偶氮唑盐法(MTT法)检测经不同浓度(0、10、50、100、200μmol/L)MC预处理后多巴胺神经元凋亡模型的活性,以此筛选出具有最佳保护作用MC浓度建立MC+MPP+组;用电泳法、流式细胞术和逆转录聚合酶链式反应分别检测MPP+组、MC+MPP+组细胞的凋亡率,以及此2组细胞caspase3mRNA的表达,并与空白对照组比较。结果(1)在MPP+为10μmol/L时可见细胞凋亡最典型的梯状DNA条带,以此浓度建立多巴胺神经元凋亡模型(MPP+组);用100μmol/LMC预处理的MPP+组细胞活性最高(P<0.05),以此作为此后实验用MC浓度。(2)MC+MPP+组细胞凋亡率及caspase3mRNA的灰度比值分别为(22.83±2.10)%及68.08±1.14,极显著低于MPP+组的(45.89±2.28)%及86.50±1.43(均P<0.01),但仍明显高于空白对照组的(11.05±1.02)%及53.75±1.23(均P<0.05)。结论MC可能通过下调caspase3mRNA表达保护MPP+诱导的PC12细胞凋亡。     

蛋白酶体抑制剂诱导多巴胺能神经元重启细胞周期的作用及机制

目的研究蛋白酶体抑制剂诱导多巴胺能神经元重启细胞周期的作用及机制。方法用蛋白酶体抑制剂lactacystin处理神经元样分化的PC12细胞,四甲基偶氮唑盐(MTT)法检测细胞活力,流式细胞仪检测早期凋亡细胞和细胞周期分布情况,RT-PCR检测细胞周期调控因子表达水平。结果经lactacys-tin处理后细胞活力呈剂量依赖性下降,出现早期凋亡细胞,随着处理时间的延长,细胞凋亡率逐渐增加;细胞周期中G0/G1期细胞减少,S期和G2/M期细胞增多;CyclinA和CyclinD1mRNA表达水平逐渐升高而Cy-clinB1mRNA表达水平无明显改变。结论蛋白酶体功能障碍通过上调细胞周期调控因子的过度表达而重新启动多巴胺能神经元的细胞周期,并诱发多巴胺能神经元细胞凋亡,产生神经元变性损伤。     

雌激素对MPP+诱导的PC12细胞损伤的防护作用

目的　探讨在离体的细胞培养物中 ,雌激素 (estrogen ,E)对 1 甲基 4 苯基吡啶离子(MPP+ )诱导的帕金森模型是否具有保护作用。方法　以PC12细胞为多巴胺能神经元的细胞模型 ,将MPP+ 或E加入培养的PC12细胞 ,四甲基偶氮唑盐 (MTT)法检测细胞活性及代谢状态 ,SABC法检测酪氨酸羟化酶 (TH)的含量 ,流式细胞术检测细胞凋亡率 ,比较各组的差异。结果　随MPP+ 浓度增加 ,细胞活性下降 ,MPP+ 浓度为 2 5 0 μmol/L时 ,吸光度A570 值为 0 30± 0 0 7,符合帕金森病细胞模型 ;随E浓度增加 ,细胞活性升高 ,呈量效依赖关系 ;当雌激素浓度 >10nmol/L ,细胞活性无明显增加。单纯用E组A570 值为 0 6 1± 0 17,比空白对照组 (0 4 9± 0 11)、MPP+ 组 (0 30± 0 0 7)、E +MPP+ 组 (0 5 6± 0 16 )细胞活性高 (P <0 0 5 ) ;TH阳性细胞平均吸光度E组 (0 4 6± 0 0 6 )比空白对照组 (0 2 2± 0 0 7)、MPP+ 组 (0 10± 0 0 3)、E +MPP+ 组 (0 2 4± 0 0 4 )高 (P <0 0 5 ) ;凋亡率E组(11 5 % )比对照组 (31 3% )、MPP+ 组 (6 3 5 % )、E +MPP+ 组 (33 6 % )低 (P <0 0 5 ) ,每组细胞数为 2× 10 5个 /ml。E +MPP+ 组比MPP+ 组细胞活性高 ,TH含量高 ,凋亡率低 (P <0 0 5 )。结论　雌激素对PC12细胞可     

99mTc-Annexin V检测早期凋亡多巴胺能神经元的实验研究

目的 研究放射性核素标记的膜联蛋白V(Annexin V)与凋亡的多巴胺能神经元的结合特性,探讨使用凋亡显像剂99mTc-Annexin V早期活体显像诊断帕金森病的可行性.方法 采用不同浓度的1-甲基-4-苯基吡啶离子(1-methyl-4-phenylpyridinium, MPP+)处理大鼠肾上腺嗜铬细胞瘤细胞(PC12)和人神经母细胞瘤细胞(SH-SY5Y)以诱导其凋亡(PC12 0～200 μm/L, SH-SY5Y 0～500 μm/L),FITC -Annexin V及碘化吡啶(propidiumiodide, PI)双染进行流式细胞仪凋亡检测.以99mTc-Annexin V与凋亡的细胞进行饱和结合实验及细胞摄取实验,研究凋亡细胞与Annexin V的亲和力及其摄取99mTc-Annexin V的动力学.结果 MPP+可诱导PC12细胞及SH-SY5Y细胞发生凋亡,并有明显的量效关系.凋亡细胞可特异性与99mTc-Annexin V结合,亲和力可达(7.16±1.78)nmol/L,每个凋亡的多巴胺能神经元表面的结合位点可达到(179±33)fmol/106cells (PC12)及(220±26)fmol/106cells (SH-SY5Y),且神经元的凋亡水平与其膜结合的99mTc-Annexin V放射性强度有相关性(P＜0.001).结论 凋亡的多巴胺能神经元与99mTc-Annexin V有高度亲和力,其所结合的99mTc-Annexin V放射性强度与细胞的凋亡水平相关,99mTc-Annexin V可用于检测多巴胺能神经元的早期凋亡.     

MPP+对培养中脑多巴胺能神经元的影响

目的通过观察MPP+对体外培养的中脑多巴胺能神经元多巴胺及胆碱摄取能力、多巴胺含量变化及细胞形态的改变等,研究MPP+对中脑多巴胺能神经元功能的影响,探讨利用MPP+建立体外PD细胞模型的可能性及实际意义.方法用孕14天Wistar大鼠,氯胺酮麻醉后取胚胎,按本室常规方法分离培养中脑多巴胺能神经元,培养至第7天后将不同浓度的MPP+加入培养有神经元的培养基中,使其终浓度分别为0.1μM,1μM,10μM.分别测定不同时相点[3H]多巴胺和[3H]胆碱摄取能力及细胞内多巴胺含量变化,并进行TH免疫细胞化学染色.结果MPP+浓度为0.1μM、1μM和10μM时,其[3H]多巴胺摄取力分别是为6.2±0.7、5.9±0.5、5.4±04,较之对照组100±1.7的结果看,MPP+对中脑多巴胺能神经元多巴胺摄取力有明显抑制作用(P＜0.05);而[3H]胆碱摄取力其值为98±3.1,较之对照组100±2.4,差异不显著,说明MPP+对多巴胺能神经元胆碱摄取力无抑制作用(P＞0.05).另一个有趣的结果是胶质细胞的存在对MPP+的作用有明显影响,未抑制胶质细胞组其作用明显强于抑制胶质细胞组(P＜0.05);同时MPP+使中脑多巴胺能神经元细胞内多巴胺含量明显减少(P＜0.05);TH阳性细胞明显减少(P＜0.05).结论MPP+对体外培养的中脑多巴胺能神经元多巴胺摄取力有明显的抑制作用,不仅使多巴胺的摄取降低,而且细胞内的多巴胺含量也显著减少,TH免疫组化染色结果也支持这一结果.MPP+对多巴胺能神经元胆碱摄取能力无明显抑制作用.     

鱼藤酮诱导细胞内泛素化α-synuclein聚集选择性损伤多巴胺神经元

目的探讨鱼藤酮对多巴胺能神经元内泛素化-αsynuclein聚集的影响及其细胞损伤作用。方法应用鱼藤酮处理经NGF诱导的神经元样分化的PC12细胞株(多巴胺能神经元)与N2a细胞株(非多巴胺能神经元)4、8、16、24 h以及用利血平预处理PC12细胞4 h再加入鱼藤酮处理16 h;采用免疫荧光双标记方法在共聚焦显微镜下观察细胞内泛素化-αsynuclein聚集,以MTT法和流式细胞术分别检测PC12细胞活力及凋亡率。结果单用鱼藤酮处理16 h后,PC12细胞株与N2a细胞株相比较,免疫荧光双标记显示PC12细胞内泛素化-αsynu-clein发生明显聚集,并且鱼藤酮对PC12细胞株的作用具有时间依赖性,而N2a细胞内泛素化-αsynuclein聚集不明显。利血平耗竭PC12细胞内多巴胺后再经鱼藤酮处理,PC12细胞内泛素化-αsynuclein聚集不明显;经不同浓度鱼藤酮处理后,细胞活力呈剂量依赖性下降;与对照组相比,经20 nmol/L鱼藤酮处理4、16、24 h后细胞存活率分别为(81.6±12.3)%、(59.8±6.7)%和(52.2±7.4)%(P<0.01)。鱼藤酮处理后出现早期凋亡细胞,随着处理时间的延长细胞凋亡率逐渐上升(P<0.01)。结论鱼藤酮选择性作用于多巴胺能神经元,使细胞内泛素化-αsynuclein发生聚集,而且这种变化具有时间依赖性,最终导致细胞发生凋亡,然而鱼藤酮对非多巴胺能神经元作用不明显。同时,鱼藤酮诱导泛素化-αsynuclein发生聚集的作用与神经元的特性存在密切关系。     

钙蛋白酶在MPP~+诱导的多巴胺能神经元损伤中的作用

目的观察钙蛋白酶在MPP+诱导的多巴胺能神经元损伤中的作用,探讨帕金森病的发病机制。方法使用神经生长因子诱导PC12细胞神经元样分化,然后使用MPP+处理神经元样分化的PC12细胞,制作帕金森病细胞模型。使用免疫印迹法检测细胞内总钙蛋白酶和活化的钙蛋白酶的表达水平,使用钙蛋白酶活性检测试剂盒观察钙蛋白酶活化水平,使用钙蛋白酶抑制剂ALLN和MDL28170抑制钙蛋白酶活性后采用MTT法检测其对细胞活性的影响,用流式细胞术观察细胞凋亡变化。结果神经元样分化的PC12细胞经MPP+处理后总的钙蛋白酶水平保持稳定,但活化的钙蛋白酶表达水平逐渐增高,钙蛋白酶活性也逐渐增高,MPP+处理12 h后达到高峰。ALLN和MDL28170能够显著抑制钙蛋白酶活性,并减轻MPP+诱导的PC12细胞损伤。钙蛋白酶抑制剂也能够明显抑制MPP+诱导的细胞凋亡。结论钙蛋白酶参与MPP+诱导的多巴胺能神经元损伤,可能是帕金森病新的治疗靶点。     

重组人促红细胞生成素预处理对黑质多巴胺能神经元凋亡的影响

目的研究重组人促红细胞生成素(rhEPO)对离体帕金森病模型中黑质多巴胺神经元凋亡的影响。方法以6-羟基多巴胺(6-OHDA)为毁损剂建立大鼠离体帕金森病(PD)模型。用6u/mlrhEPO预处理黑质多巴胺神经元,然后用免疫组化方法观察黑质中酪氨酸羟化酶(TH)免疫反应阳性细胞数和半胱天冬酶-3(Caspase-3)免疫反应阳性细胞数的变化,TUNEL法观察黑质中多巴胺神经元的凋亡情况。结果与6-OHDA组(44.2±5.0)相比,rhEPO预处理组TH免疫反应阳性细胞(63.8±6.2,P<0.01)增多;与6-OHDA组(22.3±2.8)相比,rhEPO预处理组多巴胺神经元中Caspase-3表达减少,Caspase-3免疫反应阳性细胞染色较淡,数量减少(13.7±1.8,P<0.01);与6-OHDA组(20.3±3.1)相比,rhEPO预处理组TUNEL阳性细胞染色较淡,数量减少(10.7±1.5,P<0.01)。结论rhEPO预处理可以减轻6-OHDA对离体帕金森病模型中多巴胺神经元的损伤,其机制可能与rhEPO抑制黑质多巴胺神经元凋亡有关。     

黄连碱上调miR-146a-5p后通过PI3K/AKT通路减轻由MPP+诱导的帕金森病细胞模型损伤

目的探讨黄连碱对1-甲基-4-苯基吡啶离子(MPP+)诱导的帕金森病(PD)细胞损伤的影响及其机制。方法用0.3 mmol/L的MPP+处理SK-N-SH细胞作为PD细胞模型,记为MPP+组,以正常培养的细胞作为空白对照组。用浓度分别为10μmol/L、20μmol/L、40μmol/L的黄连碱预处理4h后再用0.3 mmol/L的MPP+处理作为不同浓度黄连碱处理组。将miR-con、miR-146a-5p转染至SK-N-SH细胞后再用0.3 mmol/L的MPP+处理记为MPP++miR-con组、MPP++miR-146a-5p组;将anti-miR-con、anti-miR-146a-5p转染至SK-N-SH细胞后用20μmol/L的黄连碱预处理4h及0.3 mmol/L的MPP+处理记为MPP++Cop+anti-miR-con组、MPP++Cop+anti-miR-146a-5p组。四甲基偶氮唑盐比色法(MTT)检测细胞存活率;Western blotting实验检测活化的半胱氨酸天冬氨酸蛋白酶-3(caspase-3)、细胞周期蛋白D1(Cyclin D1)、磷酸化蛋白激酶B(p-AKT)、磷酸化磷脂酰肌醇3激酶(p-PI3K)蛋白表达水平;流式细胞术检测细胞凋亡;实时荧光定量PCR(RT-qPCR)检测miR-146a-5p表达水平。结果与空白对照组比较,MPP+处理后SK-N-SH细胞存活率显著降低,活化caspase-3表达水平显著升高,细胞凋亡率显著升高,CyclinD1、miR-146a-5p表达水平显著降低,差异均有统计学意义(P<0.05)。黄连碱处理及miR-146a-5p过表达后MPP+诱导的SK-N-SH细胞中细胞存活率显著升高,活化caspase-3表达水平显著降低,细胞凋亡率显著降低,CyclinD1、miR-146a-5p表达水平显著升高,差异均有统计学意义(P<0.05)。低表达miR-146a-5p逆转了黄连碱对SK-N-SH细胞增殖促进和凋亡抑制的作用。黄连碱处理后MPP+诱导的SK-N-SH细胞中p-AKT、p-PI3K表达水平显著升高,低表达miR-146a-5p逆转了黄连碱对p-AKT、p-PI3K表达水平的促进作用。结论黄连碱可促进细胞存活,抑制MPP+诱导的细胞凋亡,其机制可能与miR-146a-5p及PI3K/AKT信号通路有关。     

Epilepsy and anomalies of neuronal migration: MRI and clinical aspects

Neuronal migration disorders are the result of disturbed brain development. In such disorders, neurons are abnormally located. In diagnosing these conditions, magnetic resonance imaging is superior to any other imaging technique. This enables us to improve our knowledge of the clinical correlates of neuronal migration. With reference to migrational disorder, a retrospective study of all 303 patients with epileptic seizures referred for magnetic resonance imaging during a 3-year period was performed, 13 patients (aged 12-41, mean age 27) were identified. They represent 4.3% of the entire study group. Of the patients with known epilepsy, 6.7% and of the mentally retarded, 13.7% had migrational disorders. Four patients had schizencephaly as the dominant finding, one was classified as hemimegalencephaly, 2 had isolated heterotopias, and 6 had localized pachy- and/or poly-microgyria. The clinical pictures are complex. Ectopias of grey matter are recognised foci of epilepsy, but from an epileptological and a clinical viewpoint little attention has been given to these disorders. The present study shows that malmigration is not rare in epilepsy patients, especially not in the mentally retarded.     

Classification of methods in transcranial Electrical Stimulation (tES) and evolving strategy from historical approaches to contemporary innovations

Transcranial Electrical Stimulation (tES) encompasses all methods of non-invasive current application to the brain used in research and clinical practice. We present the first comprehensive and technical review, explaining the evolution of tES in both terminology and dosage over the past 100 years of research to present day. Current transcranial Pulsed Current Stimulation (tPCS) approaches such as Cranial Electrotherapy Stimulation (CES) descended from Electrosleep (ES) through Cranial Electro-stimulation Therapy (CET), Transcerebral Electrotherapy (TCET), and NeuroElectric Therapy (NET) while others like Transcutaneous Cranial Electrical Stimulation (TCES) descended from Electroanesthesia (EA) through Limoge, and Interferential Stimulation. Prior to a contemporary resurgence in interest, variations of transcranial Direct Current Stimulation were explored intermittently, including Polarizing current, Galvanic Vestibular Stimulation (GVS), and Transcranial Micropolarization. The development of these approaches alongside Electroconvulsive Therapy (ECT) and pharmacological developments are considered. Both the roots and unique features of contemporary approaches such as transcranial Alternating Current Stimulation (tACS) and transcranial Random Noise Stimulation (tRNS) are discussed. Trends and incremental developments in electrode montage and waveform spanning decades are presented leading to the present day. Commercial devices, seminal conferences, and regulatory decisions are noted. We conclude with six rules on how increasing medical and technological sophistication may now be leveraged for broader success and adoption of tES.     

Hepatic Considerations in the Use of Antiepileptic Drugs

Summary: Virtually all of the major antiepileptic drugs (AEDs) can cause hepatotoxicity, although fatal hepatic reactions are rare. The mechanisms, incidences, and risk profiles for such reactions differ from drug to drug. With carbamazepine and phenytoin, hepatotoxicity may be due to drug hypersensitivity. Although the profiles of patients at risk have not been well-defined for these two antiepileptic drugs, it would appear from reports in the literature that older adolescents and adults are at higher risk than children of developing serious or fatal hepatotoxicity. Once hepatotoxicity develops, mortality rates are 10–38% with phenytoin and 25% for carbamazepine. The risk profile for valproate fatal hepatotoxicity has been more clearly defined. Those at primary risk of fatal hepatic dysfunction are children under the age of 2 years who are receiving multiple anticonvulsants and also have significant medical problems in addition to severe epilepsy. The risk is considerably lower for patients over the age of 2 years on valproate monotherapy. In contrast to the risk profile with other AEDs, adults receiving valproate as monotherapy have the lowest risk of hepatotoxicity. Fatal hepatic dysfunction coincident with valproate may be the result of aberrant drug metabolism. Concomitant use of AEDs that induce microsomal P450 enzymes (e.g., phenytoin and phenobarbital) may enhance the production of a toxic metabolite, and hence the greater risk of hepatotoxicity with polypharmacy.     

Vascular Malformations and Epilepsy: Clinical Considerations and Basic Mechanisms

Summary: Vascular malformations (VMs) are associated with epilepsy. The natural history of the various VMs, clinical presentation, and tendency to provoke epilepsy determine treatment strategies. Investigations have probed the mechanisms of epileptogenesis associated with these lesions. Electrophysiologic changes are associated with epileptogenic cortex adjacent to VMs. Putative pathophysiologic mechanisms of epileptogenesis include neuronal cell loss, glial proliferation and abnormal glial physiology, altered neurotransmitter levels, free radical formation, and aberrant second messenger physiology.     

Neonatal Seizures: Problems in Diagnosis and Classification

Summary: The clinical identification of neonatal seizures is critical for the recognition of brain dysfunction; however, diagnosis is often difficult because of the poorly organized and varied nature of these behaviors. Current classification systems are limited in their ability to communicate motor, autonomic, and electroencephalo-graphic features of seizures precisely and to provide a basis for uniform effective diagnosis, therapy, and determination of prognosis. Recent investigations of neonates, utilizing bedside electroencephalographic/polygraphic/ video monitoring techniques, have provided the basis for improved diagnosis and classification of seizures in the newborn. These studies have demonstrated that not all clinical phenomena currently considered to be seizures require electrocortical epileptiform activity for their initiation or elaboration. In addition, the specific clinical character of the phenomena considered to be seizures, the clinical state of the infant, and the character of the EEG indicate the probable pathophysiological mechanisms involved and suggest probable etiologies, prognosis, and therapy. Similarities between animal models that demonstrate reflex physiology and neonates with motor automatisms and tonic posturing suggest that these clinical behaviors may not be epileptic in origin but, rather, primitive movements of progression and posture mediated by brainstem mechanisms. Although not all clinical behaviors currently considered to be neonatal seizures may have similar pathophysiological mechanisms, they are clinically significant because they all indicate brain dysfunction.     

Valproate Monotherapy in the Management of Generalized and Partial Seizures

Summary: For decades, therapeutic tradition has promoted the concept of polypharmacy in the management of epilepsy. In recent years, however, studies have shown that, for most patients, monotherapy can provide comparable or better seizure control than administration of multiple anticonvulsants, while diminishing the potential for adverse reactions, drug interactions, and poor compliance. Valproate is an important monotherapeutic agent that is highly effective in the control of idiopathic primary and secondarily generalized epilepsies, and partial seizures that do not generalize. Comparative studies have found that valproate is at least as effective as phenytoin and carbamazepine in the treatment of generalized and partial seizures. Given the similar efficacy, other factors such as pharmacokinetics and side effects may therefore determine anticonvulsant selection for monotherapy.     

Un nouveau cadre conceptuel de travail pour la psychiatrie

In an attempt to place psychiatric thinking and the training of future psychiatrists more centrally into the context of modern biology, the author outlines the beginnings of a new intellectual framework for psychiatry that derives from current biological thinking about the relationship of mind to brain. The purpose of this framework is twofold. First, it is designed to emphasize that the professional requirements for future psychiatrists will demand a greater knowledge of the structure and functioning of the brain than is currently available in most training programs. Second, it is designed to illustrate that the unique domain which psychiatry occupies within academic medicine, the analysis of the interaction between social and biological determinants of behavior, can best be studied by also having a full understanding of the biological components of behavior.     

Carbamazepine Efficacy and Utilization in Children

Summary: Carbamazepine is effective for preventing partial and generalized tonic-clonic seizures in children. Although absence epilepsies are more common in children than adults, an estimated 80% of children with epilepsy have seizure types or epilepsies that are potentially responsive to carbamazepine. The differential diagnosis of ictal staring is an especially important issue in children because absence and atypical absence seizures are more prevalent in children than adults. Age-related pharmacokinetic differences and drug interactions are major considerations in children. On average, children have higher clearance rates of carbamazepine, shorter half-lives, and higher ratios of carbamazepine-10, 11-epoxide to carbamazepine than adults. In addition, children with severe epilepsy are more likely to require multiple-drug therapy, which can lead to complex drug interactions. When carbamazepine is administered along with valproate, drug protein binding interactions can cause intermittent side effects.