冈田酸诱导大鼠脑tau蛋白磷酸化和神经细胞退化

采用免疫组织化学、荧光双标记技术及大鼠额叶皮质定位注射OA的方法,观察和研究蛋白磷酸酶抑制剂冈田酸(okadaic acid,OA)对大鼠脑tau蛋白高度磷酸化和神经细胞退化的影响,结果表明:①AT8免疫组织化学染色观察到在20 ng OA作用下神经细胞突起远端tau蛋白首先磷酸化,出现AT8即PHF-tau免疫阳性反应,并逐渐向胞体发展,形成营养不良的神经细胞突起和神经纤维缠结样神经细胞;②细胞计数表明额叶皮质注射20ng OA后12 h AT8免疫阳性神经细胞数显著增多(P＜0.01),1 d时达峰值(P＜0.01),3d后减少;注射OA 20,50,100 ng 1 d时均大量表达AT8阳性细胞(P＜0.05),但其各组间无显著差异;③免疫荧光双标记结果显示磷酸化tau蛋白在神经元和星形胶质细胞均存在,部分tau蛋白高度磷酸化的神经细胞TUNEL染色阳性,并伴有核浓缩断裂现象.这提示OA能有效诱导大鼠脑星形胶质细胞和神经元微管相关蛋白tau高度磷酸化,从而导致神经细胞DNA损伤;后者可能参与了OA诱导的神经细胞退化过程,其机制则有待阐明.     

Aβ25-35注射诱导大鼠海马神经元tau蛋白异常磷酸化

目的　观察大鼠海马背侧注射凝聚态Aβ2 5 3 5后 ,神经元ser199/ser2 0 2、ser396、thr2 31等位点tau蛋白磷酸化的水平以及糖原合成激酶 3β(GSK 3β)的活性变化 ,探讨Aβ2 5 3 5与tau蛋白异常磷酸化的关系及机制。方法　应用脑立体定向技术给成年大鼠海马背侧注射凝聚态Aβ2 5 3 55nmol,术后 14d ,采用镀银染色方法观察海马组织神经元病理改变 ,免疫组织化学染色方法和免疫蛋白印迹技术观察大鼠海马tau [pS3 96]、tau [pSpS199/ 2 0 2 ]、tau [pT2 3 1]的表达水平 ,免疫蛋白印迹技术检测海马GSK 3β和磷酸化GSK 3β的水平变化。 结果　凝聚态Aβ2 5 3 5组神经元纤维走行紊乱、增粗、肿胀 ,密集成宽带状 ,轴突深染。海马神经元tau [pS3 96]、tau [pSpS199/ 2 0 2 ]、tau [pT2 3 1]的阳性表达数 (分别为 38 2± 5 9,10 7 6± 8 4 ,78 4± 3 7)明显高于正常组和生理盐水组 (P <0 0 1) ,GSK 3β和磷酸化GSK 3β的水平亦明显高于正常组和生理盐水组。 结论　海马背侧注射Aβ2 5 3 5可通过激活GSK 3β诱导tau蛋白发生异常磷酸化。     

GFAP和Fos蛋白在戊四氮致痫大鼠前脑中的表达变化

目的 研究大鼠在戊四氮导致癫痫发作时前脑内星形胶质细胞和神经元的形态学反应及其相互关系。方法 应用免疫组织化学单标记法分别显示前脑内GFAP和Fos蛋白表达的时间规律，并用免疫组织化学双重标记显示GFAP和Fos蛋白表达的相互关系。结果 在戊四氮导致大鼠癫痫发作早期，前脑的星形胶质细胞被激活，细胞体积增大，突起粗大，GFAP表达阳性，随着存活时间的变化，星形胶质细胞的反应经历先逐渐升高后降低的过程。被激活的星形胶质细胞和神经元表达Fos蛋白阳性，也呈现逐渐升高又降低的变化；另外，GFAP阳性星形胶质细胞和Fos阳性神经元在前脑主要分布在大脑皮层、海马、杏仁核等部位，二者的分布特征基本一致。结论 星形胶质细胞可能和神经元一起参与了戊四氮所致癫痫发作的变化。     

脑缺血对阿尔茨海默病模型大鼠认知功能的影响及其机制探讨

目的 探讨脑缺血对阿尔茨海默病(AD)病程进展的影响及其机制.方法 采用大鼠海马注射凝聚态β-淀粉样蛋白(Aβ)1-40建立AD模型,再于海马内注射ET-1建立脑缺血条件,观察脑缺血后AD样大鼠认知功能以及海马内Aβ沉积、神经元丢失和异常磷酸化tau表达的变化;采用免疫组化、原位杂交和RT-PCR法检测海马内星形胶质细胞数量和IL-1、TNF-α表达的变化.结果 脑缺血后AD样大鼠的认知功能明显下降,海马内Aβ沉积增加,神经元丢失增加,异常磷酸化tau表达增加.星形胶质细胞的数量以及IL-1和TNF-α的表达显著增加(均P＜0.01).结论 脑缺血加重了AD样大鼠的认知功能障碍和海马病理损伤,显著增加的星形胶质细胞及IL-1和TNF-α的表达参与了这一过程.防治脑缺血和抗炎治疗可能成为减缓AD进展的新途径.     

大鼠海马注射溶血磷脂酸诱导tau蛋白高度磷酸化和凋亡研究

目的研究溶血磷脂酸(LPA)在大鼠体内对海马神经细胞tau蛋白磷酸化水平的影响和诱导神经细胞凋亡的细胞毒性作用.方法将72只SD大鼠分为实验组(n=32)、实验对照组(n=32)和对照组(n=8),利用脑立体定位技术在大鼠双侧海马微量注射溶血磷脂酸、溶剂,于注射后12、24、48和72 h各不同时间点采用免疫组化方法测定该区域神经细胞中ser202位点磷酸化tau蛋白(PS202-tau)的表达,TUNEL技术检测细胞凋亡.结果实验组LPA注射后24 h海马CA4区神经细胞中PS202-tau阳性表达到达高峰,阳性表达高于对照组和实验对照组(P＜0.05).LPA注射后48 h TUNEL阳性细胞数达高峰,每个视野中阳性细胞数多于对照组和实验对照组(P＜0.05).结论LPA在动物整体水平可诱导大鼠海马神经细胞tau蛋白高度磷酸化,并导致神经细胞发生凋亡.     

睫状神经营养因子对坐骨神经切断吻合后大鼠脊髓前角胶质纤维酸性蛋白

背景：睫状神经营养因子具有多种生物活性,在神经系统发育、分化和损伤修复中具有重要意义。 目的：观察睫状神经营养因子对坐骨神经切断吻合后大鼠相应脊髓节段前角星形胶质细胞的特异标记物胶质纤维酸性蛋白表达的影响。 方法：将SD大鼠随机分为对照组、模型组、生理盐水组及药物组。除对照组外,对所有大鼠实施双侧坐骨神经切断吻合术,药物组手术区局部注射睫状神经营养因子100 ng/kg,1次/d,生理盐水组局部注射等量生理盐水。术后1,3,7,14,21,28 d取相应脊髓节段,免疫组织化学染色观察胶质纤维酸性蛋白的表达,苏木精-伊红染色、TUNEL染色对脊髓前角神经元进行计数。 结果与结论：大鼠坐骨神经切断吻合后相应脊髓节段星形胶质细胞胞体大,突起分枝多且粗大,神经元数目逐渐减少,凋亡神经元增多,胶质纤维酸性蛋白表达增高。与模型组和生理盐水组比较,药物组神经元存活数目增多,凋亡减少,胶质纤维酸性蛋白表达明显增加(P < 0.05或P < 0.01)。同时,药物组大鼠的运动功能障碍较轻,恢复较快。说明睫状神经营养因子可以通过促进大鼠脊髓前角胶质纤维酸性蛋白的表达起到神经保护作用。 关键词：胶质纤维酸性蛋白;睫状神经营养因子;星形胶质细胞;神经元凋亡;周围神经损伤     

海马注射β-淀粉样蛋白建立阿尔茨海默病大鼠模型的实验研究

目的：海马注射β-淀粉样蛋白（Aβ）建立阿尔茨海默病（AD）大鼠模型，并进行初步评价。方法：应用凝聚态Aβ1-40进行大鼠右侧海马齿状回（DG）背侧细胞带微量注射，2周后从学州记忆、海马组织病理和异常磷酸化tau蛋白表达的变化3个方面评价大鼠模型。结果：Aβ1-40注射后大鼠Morris水迷宫学习记忆能力明显受损（P〈0．01）；注射区内DG背侧细胞带神经元丢失（P〈0．01）；注射侧海乌内Aβ沉积；海马神经元内异常磷酸化tau蛋白的表达显著增加（P〈0．01）。结论：凝聚态Aβ1-40海马注射具有明确的在体神经毒性作用，可导致大鼠认知功能下降以及海马内Aβ沉积、神经元丢失和神经元内异常磷酸化tau蛋白的表达，可成功建立AD大鼠模型。     

海马内注射纤丝状Aβ42诱导tau异常磷酸化的研究

目的　观察海马内注射纤丝状Aβ42 后神经元Ser 2 0 2位点磷酸化的tau蛋白 (PS2 0 2 tau)的表达 ,探讨Aβ42 与tau蛋白超磷酸化的关系。方法　应用立体定向技术对老年大鼠进行海马内注射纤丝状Aβ42 ,采用免疫组织化学染色方法 ,显示PS2 0 2 tau的表达情况 ,并进行图像分析。结果　纤丝状Aβ42 注射组双侧海马PS2 0 2 tau的表达明显高于正常组和双蒸水注射组 ,两侧海马PS2 0 2 tau的表达没有明显差异。结论　纤丝状Aβ42 能使PS2 0 2 tau的表达增加 ,提示它具有诱导tau蛋白超磷酸化的效应。     

再程序化星形胶质细胞的制备及体外定向分化为神经元的研究

目的探讨再程序化星形胶质细胞制备并在体外诱导其分化为神经元。方法在体外培养大鼠脑皮质来源星形胶质细胞(astrocyte),随后将提纯、鉴定过的第三代星形胶质细胞接种于12孔培养皿中,并分为A、B、C 3组。其中A组为带有绿色荧光蛋白(GFP)的慢病毒载体介导neurogenin2(Ngn2)基因转染的星形胶质细胞,制备再程序化星形胶质细胞;B组为带有GFP基因的空载体病毒转染的星形胶质细胞;C组为未进行慢病毒介导基因转染的星形胶质细胞;转基因1周后加入含细胞生长因子诱导培养基诱导分化15 d,光镜下观察各组细胞形态变化以及定向神经元分化的差异。结果 A组星形胶质细胞转基因后再诱导15 d,很大部分细胞形态呈神经元样改变,胞体呈梭形或椭圆形,有多个突起伸出且突起较长,表达神经元核蛋白(Neu N)、神经丝蛋白(NF)及神经元特异性烯醇化酶(NSE)的比例大大提高,相比B组及C组,差异有统计学意义(均P0.05);而B组与C组神经元分化比例的差异无统计学意义(P0.05)。结论慢病毒介导Ngn2基因体外转染星形胶质细胞可制备出再程序化星形胶质细胞,诱导后具有更强的向神经元定向分化能力。     

水通道蛋白4抗体对体外培养大鼠皮层神经细胞的毒性作用

目的 观察水通道蛋白4(AQP4)抗体对体外培养的大鼠皮层神经细胞的毒性作用,探讨其在视神经脊髓炎发病机制中的作用.方法 选取孕16～19 d Wistar大鼠胚胎皮层神经细胞培养3d,采用随机数字表法分为2组:对照组、AQP4抗体阳性患者血清组(抗体组).对照组以10％的比例加入正常人血清,抗体组加入等量AQP4抗体阳性患者血清培养.2h、4h、6h后使用免疫组织化学荧光染色观察星形胶质细胞、神经元和小胶质细胞形态及数量的变化.结果 对照组不同时间点3种神经细胞形态和数目无任何变化:抗体组2h后就出现星形胶质细胞肿胀、小胶质细胞体积增大以及神经元轴突断裂等形态学的改变,但3种细胞数量无明显变化:4h后星形胶质细胞和神经元比例分别为(24.73+5.27)％和(35.49+8.43)％,明显少于对照组[(30.34±4.53)％和(48.60±1 0.99)％],差异有统计学意义(p＜0.05);小胶质细胞比例较对照组明显增多[分别为(27.35±13.17)％和(16.44±2.70)％],差异有统计学意义(P＜0.05);6 h后3种细胞数量变化更为明显(P＜0.05).结论 AQP4抗体能导致体外培养的大鼠皮层星形胶质细胞和神经元死亡以及小胶质细胞的活化,推测其在视神经脊髓炎的发病机制中发挥一定作用.     

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.     

Diagnostic Difficulties and Treatment Implications

Summary: Differentiation between types of epileptic seizures has been aided in recent years by the introduction of intensive neurodiagnostic techniques and the development of increasingly detailed classification systems. Paradoxically, these developments have not simplified the task of matching the appropriate antiepileptic drug to a particular seizure type. It is reasonable to assume that anticonvulsant drugs will have different effects on different types of seizures, but faulty, circular reasoning can enter the picture if one also assumes that responses of seizures to different drugs signify different seizure types. There are several examples of differential diagnoses that can fall prey to this problem, including the diagnosis between partial seizures with secondary generalization and generalized tonic-clonic seizures, and the diagnosis between complex partial seizures and absence seizures with automatisms, among others. Considerations of etiology in future classification systems can further complicate the problem: should one then choose an anticonvulsant drug on the basis of individual seizure type or on the basis of the type of epilepsy? Ramifications of this issue extend even to the drug approval process. Official sanction is not given for use of a drug for a seizure type not included in the original efficacy studies, even if later scientific evidence shows that seizure type to be related to a type that is included. New trials must be undertaken. These problems arise from how we choose to classify seizures.     

Cognitive Dysfunction Associated with Antiepileptic Drug Therapy

Summary: Epilepsy is frequently associated with cognitive dysfunction. However, the reasons for this correlation are unclear. Possible influential factors include patient age; duration, frequency, etiology, and type of seizures; hereditary factors; psychosocial issues; and antiepileptic drug (AED) therapy. Whereas many of these factors are beyond the physician's control, AED therapy is one element that can be addressed in treatment decisions by recognizing the potential cognitive effects of particular AEDs. For example, phenobarbital impairs memory and concentration; phenytoin affects attention, problem solving ability, and performance of visuomotor tasks. In contrast, carbamazepine may affect concentration, while valproate would appear to have minimal effects on cognition. Moreover, cognitive effects of AEDs are amplified with coadministration of multiple anticonvulsants (polytherapy). A review of studies on the cognitive effects of monotherapy with AEDs, as opposed to those of polytherapy, provides evidence that drug-related cognitive dysfunction can be reversed if patients are switched to a simpler therapeutic regimen. Future research should be directed toward developing reliable measures for assessing and monitoring cognition, and understanding the particular cognitive side effects of each AED. Physicians also need to revise their opinions about which side effects are "tolerable" for epileptic patients.     

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.     

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.     

Carbamazepine Efficacy in Adults With Partial and Generalized Tonic-Clonic Seizures

Summary: Carbamazepine and phenytoin are drugs of choice in initial monotherapy for adult partial and secondarily generalized tonic-clonic seizures. These designations reflect the results of the Veterans Administration Epilepsy Cooperative Study Group of 1985. An earlier comparative study of carbamazepine and phenytoin by Ramsay and associates found both drugs equally effective in controlling new-onset seizures. Among the advantages of carbamazepine is that it causes relatively few cognitive and dysmorphic side effects. Its disadvantages are its unavailability in parenteral formulation and its metabolic autoinduction. The latter must be compensated for by planned dosage increases to maintain therapeutic plasma steady-state levels during the first 2 or 3 months of treatment. Carbamazepine is judged a drug of choice in the treatment of these secondarily generalized tonic-clonic seizures, and the drug of choice in children, adolescents, and women susceptible to the dysmorphic side effects associated with other anticonvulsant agents.     

Etiologic and Preventive Aspects of Epilepsy in the Child–Bridging the Gap Between Laboratory and Clinic

Summary: Four broad categories of basic phenomena are pertinent to developing ways to prevent epilepsy. These include mechanisms of epileptogenesis, ictal initiation and temporary entrainment by the seizure discharge of normally functioning brain, seizure propagation, and control mechanisms that function both to restrain the cascade of epileptic events culminating in a seizure and to arrest the epileptic event and restore the interictal state. In newborns and children, hypoxia-ischemia is a major factor leading to epileptogenesis, and several schemes are proposed to classify, quantify, and prevent hypoxic-ischemic encephalopathy. Control mechanisms must be better understood in order to develop prophylactic recommendations for epilepsy, and an experimental model of "kindling antagonism" may increase our understanding of these. Programs of prevention of seizures in children will evolve only if basic researchers and clinicians work productively together to develop an adequate understanding of factors important in epileptogenesis and antiepileptogenic control mechanisms.     

Predisposing and Causative Factors in Childhood Epilepsy

Summary: We review information from large studies of defined populations, examining the role of known factors and especially of prenatal and perinatal factors in contributing to nonfebrile seizure disorders of early childhood. We depend especially, but not exclusively, on the recently completed analyses from the Collaborative Perinatal Project of the National Institute of Neurological and Communicative Disorders and Stroke, the NCPP. About 4% of children in the NCPP who had at least one non-febrile nonsymptomatic seizure by the age of 7 years had a previous seizure during acute neurologic illness, such as meningitis or during the acute illness after trauma. Many such seizures should potentially be preventable. Of children with seizures, 10% had had a neonatal seizure and 13% had had a febrile seizure. Among the hundreds of prenatal and perinatal factors explored as predictors of childhood seizure disorders, the principal predictors identified were congenital malformations of the fetus, cerebral and noncerebral; family history of certain neurologic disorders; and neonatal seizures. In agreement with the British National Child Development Study, labor and delivery factors in the NCPP appeared to contribute very little to childhood seizure disorders. Maldevelopment, rather than damage at birth to an initially intact nervous system, appeared to be the more common mechanism. Most seizure disorders of early childhood remained unexplained by the large set of prenatal and perinatal characteristics examined.     

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.