MiRNA-132上调脑源性神经营养因子表达抑制β-淀粉样蛋白诱导的神经元损伤研究

研究背景脑源性神经营养因子(BDNF)在阿尔茨海默病(AD)发病机制中发挥重要作用,微小RNA-132(mi RNA-132)在神经元呈高表达,可以通过调控靶基因表达参与BDNF介导的神经发育过程。本研究旨在探讨阿尔茨海默病神经元模型中mi RNA-132与BDNF的调控关系和神经保护作用。方法体外培养海马神经元72 h后慢病毒转染mi RNA-132,并于体外培养第7天以β-淀粉样蛋白(Aβ)处理制备阿尔茨海默病神经元模型;实时荧光定量聚合酶链反应观察对照组与AD组mi RNA-132表达差异以及不同处理组BDNF m RNA表达变化,噻唑蓝法观察不同处理方式对细胞活性的影响。结果 (1)AD组海马神经元mi RNA-132(t=13.888,P=0.000)和BDNF m RNA(t=-12.274,P=0.000)表达水平均低于对照组。(2)原代培养的海马神经元经慢病毒转染后倒置相差荧光显微镜可见绿色荧光蛋白,对照组(t=16.135,P=0.000)和AD组(t=8.656,P=0.000)转染过表达mi RNA-132后均能上调BDNFm RNA表达。(3)AD组海马神经元活性降低(t=-6.023,P=0.000),AD组转染mi RNA-132后神经元活性增强(t=3.385,P=0.007),予以外源性BDNF共培养后神经元活性明显改善(t=3.672,P=0.004)。结论阿尔茨海默病神经元模型mi RNA-132和BDNF表达水平均下降,mi RNA-132可上调BDNF表达,提示mi RNA-132和BDNF对阿尔茨海默病神经元模型具有神经保护作用,有望为阿尔茨海默病诊断与治疗提供新的视角。     

C型Niemann-Pick病小鼠P27kipl表达异常与神经元变性和星形胶质细胞增生

目的探讨细胞周期蛋白抑制物P27kipl在NPC小鼠模型中神经元变性、死亡及星形胶质细胞增生中的作用.方法利用免疫组化和免疫荧光技术检测NPC-1小鼠脑部P27kipl表达及胶质细胞增殖的情况.结果 P27pipl在野生型小鼠大脑皮质、海马、基底节、脑干广泛的神经元及小脑Purkinje细胞均有较强的表达, 而且在部分胶质细胞也存在免疫反应性, 而在NPC小鼠的基底节、脑干神经元及小脑Purkinje细胞中P27kipl的表达明显弱于野生型小鼠.GFAP阳性星形胶质细胞出现P27kipl表达上调, 其细胞数在NPC小鼠大脑皮质、海马及脑干(尤其在桥脑处)显著增多, 提示星形胶质细胞异常增生.结论在NPC小鼠中枢神经元发生病变的同时, 星形胶质细胞也发生了明显的病理性增生, 细胞周期蛋白酶抑制物P27kipl失调参与了这一病理过程.     

PINK1介导缺氧损伤时星形胶质细胞对神经元的保护作用

目的探究星形胶质细胞内PTEN诱导假定激酶1(PINK1)缺失对缺血时神经保护作用的影响及其作用机制。方法离体培养原代星形胶质细胞,使用小干扰RNA(si RNA)沉默PINK1表达,氧糖剥夺(OGD)建立细胞缺氧模型,分为4组:PINK1沉默组(si RNA+转染剂)、空质粒组(空质粒+转染剂)、转染剂组(只加转染剂)和对照组(星形胶质细胞),各组均与神经元共培养;另设立神经元单独培养组。免疫荧光染色观察神经元凋亡情况。定量PCR及ELISA检测星形胶质细胞促红细胞生成素(EPO)及血管内皮生长因子(VEGF)表达量;Western blot检测星形胶质细胞内缺血诱导因子(HIF)及核因子κB(NF-κB)通路相关蛋白水平。结果 OGD损伤后神经元凋亡率较高,与星形胶质细胞共培养后神经元凋亡率显著降低(P0.05)。PINK1基因沉默后共培养神经元凋亡增加,星形胶质细胞EPO及VEGF分泌量减少、胞内EPO及VEGF转录水平降低(P0.05);HIF-1、HIF-2与NF-κB通路活化水平均显著降低(P0.05)。结论星形胶质细胞对OGD损伤神经元有保护作用,其作用通过EPO及VEGF实现;PINK1基因沉默后星形胶质细胞对缺血神经元保护作用减弱,可能与NF-κB通路活化水平降低、HIF激活受损进而下调EPO和VEGF表达量有关。     

成年大鼠神经元和星形胶质细胞细胞周期蛋白依赖性激酶抑制因子表达的差异研究

目的比较研究成年大鼠细胞周期蛋白依赖性激酶抑制因子在神经元和星形胶质细胞的表达差异。方法应用免疫荧光和激光扫描共聚焦显微镜观察成年大鼠生理状态下大脑皮层或海马CA1、CA3、DG区神经元和星形胶质细胞细胞周期蛋白依赖性激酶抑制因子(CDKI)p15Ink4b、p21cipl的表达。结果成年大鼠海马区和大脑皮层的神经元有p15Ink4b和p21cipl的表达,细胞核和细胞浆均有表达,且以胞核为主;星形胶质细胞也有上述细胞周期调控蛋白的表达,便细胞数目较少,并且表达这些指标的星形胶质细胞多聚集在海马区。结论成年大鼠大脑皮层和海马区的神经元和星形胶质细胞均表达p15Ink4b和p21cipl,而其在神经元的表达较星形胶质细胞更为普遍。     

盐酸小檗碱对颅脑创伤模型小鼠双侧丘脑继发性损伤的神经保护作用

目的探讨盐酸小檗碱对颅脑创伤(TBI)模型小鼠双侧丘脑继发性损伤(炎症反应、氧化损伤和神经元缺失)的神经保护作用。方法采用自由落体撞击法制备颅脑创伤模型,盐酸小檗碱组小鼠予以盐酸小檗碱50 mg/(kg·d)灌胃21 d,TBI组予等量生理盐水灌胃21 d,对照组不予自由落体撞击。免疫组织化学染色计数双侧丘脑诱导型一氧化氮合酶(i NOS)、环氧合酶-2(COX-2)、8-羟基脱氧鸟苷(8-OHd G)和神经元核抗原(Neu N)阳性神经元或胶质细胞数目,免疫荧光染色计数双侧丘脑胶质纤维酸性蛋白(GFAP)阳性星形胶质细胞和离子钙结合蛋白1(Iba1)阳性小胶质细胞数目。结果 3组小鼠颅脑创伤同侧丘脑i NOS(P=0.015)、COX-2(P=0.022)、8-OHd G(P=0.000)和Neu N(P=0.000)阳性神经元或胶质细胞数目以及GFAP阳性星形胶质细胞数目(P=0.024)和Iba1阳性小胶质细胞数目(P=0.000)差异均有统计学意义,其中,TBI组i NOS(P=0.005)、COX-2(P=0.011)和8-OHd G(P=0.000)阳性神经元或胶质细胞数目以及GFAP阳性星形胶质细胞数目(P=0.011)和Iba1阳性小胶质细胞数目(P=0.000)均高于对照组,而Neu N阳性神经元数目低于对照组(P=0.000);盐酸小檗碱组i NOS(P=0.031)、COX-2(P=0.024)和8-OHd G(P=0.008)阳性神经元或胶质细胞数目以及GFAP阳性星形胶质细胞数目(P=0.031)和Iba1阳性小胶质细胞数目(P=0.012)均低于TBI组,仅8-OHd G阳性神经元数目(P=0.014)和Iba1阳性小胶质细胞数目(P=0.024)仍高于对照组,而Neu N阳性神经元数目高于TBI组(P=0.016)、仍低于对照组(P=0.027)。3组小鼠颅脑创伤对侧丘脑仅COX-2(P=0.029)和8-OHd G(P=0.000)阳性神经元或胶质细胞数目差异有统计学意义,其中,TBI组COX-2(P=0.011)和8-OHd G(P=0.000)阳性神经元或胶质细胞数目高于对照组,盐酸小檗碱组COX-2(P=0.047)和8-OHd G(P=0.010)阳性神经元或胶质细胞数目低于TBI组,仅8-OHd G阳性神经元数目仍高于对照组(P=0.004)。结论颅脑创伤可以引起双侧丘脑继发性损伤,尤以同侧丘脑显著,对侧丘脑仅出现炎症反应和氧化损伤;盐酸小檗碱通过抑制颅脑创伤后双侧丘脑炎症反应和氧化损伤而发挥神经保护作用。     

ADDLs对原代培养小鼠皮层神经元及星形胶质细胞混合培养体系Notch-1信号转导及HIF-1α表达的影响

目的探讨Aβ寡聚体(ADDLs)对原代培养小鼠皮层神经元及星形胶质细胞混合培养体系Notch-1信号转导及HIF-1α蛋白表达的影响。方法在原代培养小鼠皮层神经元及星形胶质细胞混合培养体系的基础之上应用CCK-8法观察Aβ寡聚体对混合培养体系细胞活力的影响,并应用免疫印迹的方法检测Aβ寡聚体对混合培养体系的NICD及HIF-1α水平的影响。另外,应用qPCR的方法检测凋亡相关caspase-3mRNA水平。结果 Aβ寡聚体干预浓度在高于2μM的情况下可使混合培养体系细胞活力水平明显降低,并呈现浓度依赖。10μM的ADDLs明显升高了原代混合培养体系的NICD及HIF-1α蛋白表达水平,且均呈现出相对的时间依赖性,同时这两种蛋白表达水平的变化表现出基本一致的趋势。同时,10μM的ADDLs明显上调了混合体系的caspase-3 mRNA水平。结论 Aβ寡聚对原代培养小鼠皮层神经元及星形胶质细胞混合培养体系的毒性作用与上调NICD及HIF-1α表达水平密切相关。     

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。     

大鼠海马发育过程中神经元和星形胶质细胞p21Cip1的表达

目的研究大鼠海马发育过程中细胞周期蛋白依赖性激酶抑制因子p21Cip1在神经元和星形胶质细胞中的表达。方法应用免疫双标技术和流式细胞术检测p21Cip1在生后1d(P1),生后11d(P11),成年和老年大鼠的海马神经元和星形胶质细胞中的表达。结果 (1)p21Cip1在各个年龄组大鼠的海马神经元和星形胶质细胞中均有表达;(2)大鼠海马神经元和星形胶质细胞中p21Cip1在不同年龄组的表达趋势类似,均在P1表达水平最高;而从P11到老年组p21Cip1的表达则逐渐增高,且各组间p21Cip1的表达有显著性差异(P0.05)。结论 p21Cip1在大鼠海马神经元和胶质细胞中的表达随着大鼠的发育而变化,这提示p21Cip1可能在大鼠海马的发育过程中起重要作用。     

P2Y1受体介导星形胶质细胞的激活在急性一氧化碳中毒迟发性脑病中的作用

目的 探讨P2Y1受体和星形胶质细胞在急性一氧化碳(CO)中毒迟发性脑病(DEACMP)中的作用以及DEACMP可能的发病机制。方法 经水迷宫实验筛选认知功能合格的雄性SD大鼠，随机分为两组：对照组、CO中毒组，CO中毒组制作DEACMP模型，分别于造模后第7天、第14天、第21天、第28天对比两组行为学改变，神经元变化以及海马组织中P2Y1受体和星型胶质细胞的表达。结果 通过水迷宫发现与对照组相比，造模后第21天、第28天CO中毒组大鼠逃避潜伏期均明显延长(P<0.05);HE染色发现造模后第14天、第21天、第28天模型组大鼠海马锥体细胞及神经元坏死明显，结合水迷宫可表明大鼠在21 d时出现DEACMP;与对照组相比，Western blot法检测提示各时间点CO中毒组海马区P2Y1及GFAP蛋白表达均增多(P<0.05),呈先升高后降低的趋势；免疫荧光表明海马区P2Y1和GFAP存在共表达，相对于对照组，中毒后各时间点海马CA₁区P2Y1和GFAP都有表达上调(P<0.05)。结论 P2Y1受体对星形胶质细胞的激活可能是DEACMP的发病机...     

星形胶质细胞条件培养液体外诱导胎鼠室管膜前下区神经干细胞向多巴胺能神经元的分化

背景：在神经干细胞移植治疗神经系统退行性变及修复神经系统功能损伤过程中,有效的神经干细胞体外增殖与多巴胺能神经元的定向诱导分化尤为关键。 目的：以星形胶质细胞条件培养液为诱导剂,观察胎鼠室管膜前下区神经干细胞体外向多巴胺能神经元的分化。 设计、时间及地点：细胞学体外对照观察,于2006-12/2007-08在解放军第三军医大学新桥医院实验中心完成。 材料：清洁级新生2 d龄KM小鼠15只,孕16 d Wistar大鼠40只,均由解放军第三军医大学实验动物中心提供。 方法：采用差速黏附法和振荡分离法纯化培养KM小鼠星形胶质细胞,收集传至第3代、培养5 d的星形胶质细胞条件培养液,-20 ℃冻存待用。体外分离Wistar胎鼠室管膜前下区神经干细胞,加入含B27和碱性成纤维细胞生长因子的DMEM/F12无血清培养基进行原代培养,传至第3代后按0.5×108 L-1密度接种,设立2组：对照组单纯加入含体积分数0.1为胎牛血清的DMEM/F12培养基予以自然分化,实验组加入已制备的星形胶质细胞条件培养液进行诱导分化。 主要观察指标：免疫细胞化学染色鉴定胎鼠室管膜前下区神经干细胞,流式细胞仪检测胎鼠室管膜前下区神经干细胞向多巴胺能神经元分化的阳性率。 结果：培养的神经球细胞表达巢蛋白,可分化为神经元特异性烯醇化酶、胶质纤维酸性蛋白阳性细胞。诱导分化7 d后,实验组可见酪氨酸羟化酶阳性细胞,胞体呈圆形或椭圆形,酪氨酸羟化酶位于胞质及突起中;对照组酪氨酸羟化酶阳性细胞在数量、细胞成熟形态上均未达到实验组水平。实验组酪氨酸羟化酶阳性细胞分化率明显高于对照组（t=35.296,P < 0.01）。 结论：在体外星形胶质细胞条件培养液可显著促进胎鼠室管膜前下区神经干细胞向多巴胺能神经元分化。     

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 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.     

Treatment Considerations in Anticonvulsant Monotherapy

Summary: The long-standing practice of polypharmacy in treating epilepsy is giving way to use of monotherapy. Monotherapy can improve seizure control as well as reduce the risk of serious idiosyncratic reactions, dose-related side effects, and complex drug interactions. Monotherapy also offers improved compliance and cost-effectiveness. The basis of monotherapy is accurate diagnosis and assessment of the patient's seizure type(s), followed by selection of a single appropriate anticonvulsant drug. Many patients currently treated with multiple anticonvulsants can be successfully converted to monotherapy with a carefully monitored program in which troublesome and redundant drugs are gradually withdrawn from the therapeutic regimen.     

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.     

Anticonvulsant Drugs and Cognitive Function: A Review of the Literature

Summary: Alterations of cognitive function are separate from disturbances of behavior seen in association with epilepsy. The nature of the cognitive disability may to a certain extent depend on the seizure type. Partial seizures, mainly derived from a temporal lobe focus, impair memory tasks, while generalized seizures seem to have more effect on attentional abilities. A number of studies, reviewed in this paper, suggest that anticonvulsant drugs further impair cognitive function. Maximal impairments are seen in patients receiving polytherapy: rationalization of polytherapy improves cognitive abilities. Studies in children and adults have allowed differentiation of the effects of various commonly used antiepileptic agents. Maximal cognitive deficits are seen with. phenytoin, while phenobarbital and sodium valproate induce moderate disturbances, and carbamazepine seems relatively free from such toxicity. Further research is needed on the interrelationship between types of seizure disorders, types of anticonvulsant medications, and cognitive function.     

Dextromethorphan: Cellular Effects Reducing Neuronal Hyperactivity

Summary: Dextromethorphan is a dextrorotary morphinan without affinity for opioid receptors, commonly used as an antitussive medication. During the past 5 years, interest in the compound and its demethylated derivative, dextrorphan, has been revived because additional neuroprotective and an-tiepileptic properties were found in in vitro studies, animal experiments, and a few clinical cases. Both morphinans are able to inhibit N -methyl-D-aspartate (NMDA) receptor channels and voltage-operated calcium and sodium channels with different potencies. The inhibition of the NMDA receptor is believed to be the predominant mechanism of action responsible for the anticonvulsant and neuroprotective properties of the compounds.