谷氨酸的神经毒性与精神分裂症的发生发展

一直占统治地位的多巴胺功能亢盛假说对于精神分裂症发生、发展的全部过程已难以作出解释，因此，不少学者便寻求多方面的证据对其修正和发展。其中有两个主要内涵，其一，精神分裂症的异质性与多巴胺功能的关系，其二，多巴胺与其他神经介质的相互作用，也包括与其他精神活性物质，如某些氨基酸或神经肽之间的相互作用。     

谷氨酸的兴奋性神经毒性作用与中枢神经系统损伤

谷氨酸(Glu)具有兴奋性神经毒性,其毒性作用与促进Na~+、Cl~-、水内流、Ca~(++)超载、自由基及一氧化氮的介导有关,参与多种急慢性脑损伤的发生。本文重点综述了Glu的神经毒性作用和机制及其在各种急慢性中枢神经系统损伤中的可能作用。     

谷氨酸受体脱敏机制及神经保护作用

谷氨酸受体在脊椎动物中枢神经系统中介导大多数的兴奋性传递，但是，谷氨酸受体的过度兴奋会引起导致神经元死亡的兴奋毒性过程。受体的脱敏可以阻断这一过度兴奋的过程。本文根据近年来的文献报道，对谷氨酸受体的脱敏机制以及受体脱敏所具有的神经保护作用作一简要论述。     

脑室内神经干细胞移植修复谷氨酸导致的成年小鼠神经损伤

目的探讨脑室内神经干细胞移植修复成年小鼠谷氨酸神经毒性损伤的可能性。方法从15日小鼠胚胎脑组织分离神经干细胞,采用免疫细胞化学技术检测细胞Nestin抗原表达;通过免疫荧光染色观察所移植神经干细胞在体内的存活及定位。除对照组外,所有小鼠均以谷氨酸单钠（每天4.0 g/kg）灌胃,连续10天。灌胃后第1 天和10 天,谷氨酸加神经干细胞移植组行神经干细胞脑室内移植（1× 105细胞 /鼠）,对照组和谷氨酸组注射DMEM 液。末次移植后第 11天进行Y迷宫试验,试验结束后进行小鼠脑病理检查,以分析谷氨酸引起的脑功能和形态学上的改变。结果所分离细胞呈Nestin阳性表达;移植10天后所移植神经干细胞在小鼠脑中呈区域特异性存活;脑室内移植神经干细胞能明显促进成年小鼠脑谷氨酸兴奋性毒性损伤的修复。结论脑室内移植神经干细胞可用于疾病或损伤脑组织的修复。     

脑室内神经干细胞移植修复谷氨酸导致的成年小鼠神经损伤(英文)

目的探讨脑室内神经干细胞移植修复成年小鼠谷氨酸神经毒性损伤的可能性。方法从15日小鼠胚胎脑组织分离神经干细胞,采用免疫细胞化学技术检测细胞Nestin抗原表达;通过免疫荧光染色观察所移植神经干细胞在体内的存活及定位。除对照组外,所有小鼠均以谷氨酸单钠(每天4.0 g/kg)灌胃,连续10天。灌胃后第1 天和10 天,谷氨酸加神经干细胞移植组行神经干细胞脑室内移植(1× 105细胞 /鼠),对照组和谷氨酸组注射DMEM 液。末次移植后第 11天进行Y迷宫试验,试验结束后进行小鼠脑病理检查,以分析谷氨酸引起的脑功能和形态学上的改变。结果所分离细胞呈Nestin阳性表达;移植10天后所移植神经干细胞在小鼠脑中呈区域特异性存活;脑室内移植神经干细胞能明显促进成年小鼠脑谷氨酸兴奋性毒性损伤的修复。结论脑室内移植神经干细胞可用于疾病或损伤脑组织的修复。     

谷氨酸受体脱敏机制及神经保护作用

谷氨酸受体在脊椎动物中枢神经系统中介导大多数的兴奋性传递,但是,谷氨酸受体的过度兴奋会引起导致神经元死亡的兴奋毒性过程.受体的脱敏可以阻断这一过度兴奋的过程.本文根据近年来的文献报道,对谷氨酸受体的脱敏机制以及受体脱敏所具有的神经保护作用作一简要论述.     

阿魏酸钠对慢性脑缺血大鼠的神经保护作用机制研究

目的探讨阿魏酸钠对慢性脑缺血大鼠的神经保护作用及其机制。方法以双侧颈总动脉结扎(2-VO)法制备慢性脑缺血模型,于术后6周分别给予阿魏酸钠和PBS干预,分为阿魏酸钠干预组和模型对照组。另设假手术组(仅分离双侧颈总动脉,但不结扎)作为空白对照。术后8周行Morris水迷宫实验,评价大鼠的空间学习记忆功能,同时观察双侧颞叶内侧缺血区脑组织血管密度、激光共聚焦法检测毛细血管内径、缺血边界地区的毛细血管分支点数目和微血管总面积等指标、海马细胞增殖情况(免疫组化法)和血浆血管内皮生长因子(VEGF)水平(ELISA法检测),以探讨其可能的机制。结果 Morris水迷宫结果显示,阿魏酸钠干预组第2、3、4、5天逃避潜伏期[分别为(43.55±6.34)s、(38.11±1.20)s、(34.75±5.30)s、(24.39±3.93)s]明显短于模型对照组[分别为(50.89±6.31)s、(43.72±8.21)s、(50.79±9.36)s、(44.39±3.93)s,均P0.01];阿魏酸钠干预组第一象限游泳时间明显长于模型对照组[分别为(27.36±3.89)s、(14.68±2.36)s,P=0.002]。阿魏酸钠干预组毛细血管内径与模型对照组比较变短[分别为(3.02±0.21)μm、(3.35±0.18)μm,P=0.003],阿魏酸钠干预组缺血边界地区的毛细血管分支点数目与模型对照组同源组织区比较显著增加(分别为205.80±12.70、158.42±10.92,P=0.001),0.002mm3体积内阿魏酸钠干预组微血管总面积与模型对照组比较明显增加[分别(83389±4026)μm2、(73349±3986)μm2,P=0.004]。阿魏酸钠干预组缺血脑组织内的BrdU阳性细胞数明显高于模型对照组(分别为23.82±3.05、10.26±2.89,t=18.26,P=0.004)。阿魏酸钠干预组VEGF水平明显高于模型对照组[分别为(67.58±9.61)pg/mL、(21.90±5.16)pg/mL,P=0.008]。结论阿魏酸钠可以显著改善慢性脑缺血大鼠的空间学习记忆能力,其机制可能与VEGF介导的血管密度增加有关。     

谷氨酸兴奋性毒性模型的研究

目的探讨谷氨酸兴奋性毒性模型培养液各成分中谷氨酸的含量及模型培养前后培养液中谷氨酸的变化。方法应用脊髓器官型培养模型,随机分成对照组和苏-羟天冬氨酸(THA)组,用免疫组化法检测运动神经元数目,用多功能酶标仪检测培养基中谷氨酸的含量。结果最小基础培养基和马血清中均含有谷氨酸。经过4w培养后,THA组培养液中谷氨酸的含量明显高于对照组(P<0.05),运动神经元数目较对照组减少(P<0.05)。结论 THA诱导的脊髓器官型培养模型可以模拟肌萎缩侧索硬化运动神经元变性,作为谷氨酸兴奋性毒性模型,我们在应用它时一定要严格检测培养液中谷氨酸的含量,每一个处理因素都要考虑其对谷氨酸的影响。     

胆红素的神经毒性作用

脑出血后血肿周围脑组织水肿的形成是脑出血后继发脑损伤的一个重要因素。脑水肿形成的机制仍有多处需待阐明。研究证实 ,水肿的形成涉及血肿代谢产物如铁离子、血红素、CO等的毒性作用。本文将对作为血肿代谢终产物之一的胆红素的神经毒性作用作一综述     

帕金森病的神经保护治疗进展

帕金森病（Parkinson disease,PD）是病因未明、老年期常见的神经变性病,主要病理基础为黑质致密部多巴胺（d—pamine,DA）能神经元变性、缺失和残存神经元胞浆中出现路易小体（Lewy body）。累积的证据显示,氧化应激、线粒体功能障碍、神经营养因子下调、钙超载、兴奋性氨基酸毒性作用、细胞凋亡等病理机制参与了PD的发生和／或发展。     

NMDA preconditioning protects against seizures and hippocampal neurotoxicity induced by quinolinic acid in mice

PURPOSE: N-methyl D-aspartate (NMDA) preconditioning has been used to prevent cellular death induced by glutamate or NMDA in cultured neurons. Quinolinic acid (QA)-induced seizures are used to average NMDA receptors-evoked neurotoxicity in animal models. The purpose of this study was to investigate the potential neuroprotective effects of NMDA preconditioning against QA-induced seizures and hippocampal damage in vivo. METHODS: Mice were pretreated with nonconvulsant doses of NMDA for different times before i.c.v. QA infusion and observed for the occurrence of seizures. Hippocampal slices from mice were assayed to measure cellular viability. RESULTS: NMDA preconditioning presented 53% protection against QA-induced seizures, as well as QA-induced cellular death in the hippocampus. The NMDA receptor antagonist, MK-801, prevented the protection evoked by NMDA preconditioning. The adenosine A1 receptor antagonist, CPT, prevented the protection evoked by NMDA preconditioning against QA-induced seizures, but not against QA-induced hippocampal cellular damage. The adenosine A1 receptor agonist, CPA, did not mimic the NMDA preconditioning-evoked protective effects. CONCLUSIONS: These results suggest that in vivo preconditioning with subtoxic doses of NMDA protected mice against seizures and cellular hippocampal death elicited by QA, probably through mechanisms involving NMDA receptors operating with adenosine A1 receptors.     

Quinolinate and kainate neurotoxicity in neostriatal cultures is potentiated by co-culturing with neocortical neurons

It has been suggested that a disorder in the regulation of excitatory amino acids (EAA) may underlie the loss of neostriatal neurons seen in Huntington's disease. The role of neocortical afferent fibers in determining the EAA sensitivity of neostriatal neurons was assessed by comparing EAA toxicity in co-cultures of neocortex and neostratum with that of neostriatum alone. In culturesalone, EAAs produced only modest neuronal losses. Kainate, which tended to be the most potent excitotoxin, produced a loss of approximately 30% of the neurons after a 5-min exposure at a 1-mM concentration. In co-cultures, the sensitivity of neostriatal neurons to EAA toxicity was dramatically enhanced; toxicity was increased about two-fold for kainate and quinolinate at millimolar concentrations and as much as 8-fold for quinolinate at micromolar concentrations. The effects of EAA co-incubation with the N-methyl-d-aspartate (NMDA) receptor antagonist, 2-amino-5-phosphonovaleric acid, suggested that the toxic actions of quinolinate, but not kainate, were mediated largely by NMDA receptors.     

Tumor necrosis factor-α attenuates N-methyl-d-aspartate-mediated neurotoxicity in neonatal rat hippocampus

Tumor necrosis factor-α (TNFα) has been implicated in the pathophysiology of acute neonatal brain injury. We hypothesized that acute brain injury would induce TNFα expression and that exogenous TNFα would influence the severity of N-methyl-d-aspartate-induced tissue damage. We performed two complementary groups of experiments to evaluate the potential role(s) of TNFα in a neonatal rodent model of excitotoxic injury, elicited by intracerebral injection of N-methyl-d-aspartate. We used immunohistochemistry and ELISA to evaluate N-methyl-d-aspartate-induced changes in TNFα expression, and we co-injected TNFα with N-methyl-d-aspartate, to evaluate the effect of this cytokine on the severity of tissue injury. Both intra-hippocampal and intra-striatal injection of N-methyl-d-aspartate (5 nmol) stimulated TNFα expression. Increased TNFα expression was detected 3–12 h after lesioning; TNFα was localized both in glial cells in the corpus callosum, and in cells with the morphology of interneurons in the ipsilateral hippocampus, striatum, cortex and thalamus. Intra-hippocampal or intra-striatal administration of TNFα (50 ng) alone did not elicit neuropathologic damage. In the hippocampus, when co-injected with N-methyl-d-aspartate (5 or 10 nmol), TNFα (50 ng) attenuated excitotoxic injury by 35%–57%, compared to controls co-injected with heat-treated TNFα. In contrast, in the striatum, co-injection of TNFα with N-methyl-d-aspartate had no effect on the severity of the ensuing damage. The data indicate that TNFα is rapidly produced in glial cells and neurons after an excitotoxic insult in the neonatal rat brain, and that administration of exogenous TNFα results in region-specific attenuation of excitotoxic damage. We speculate that endogenous TNFα may modulate the tissue response to excitotoxic injury in the developing brain.     

Investigations of neurotoxicity and neuroprotection within the nucleus basalis of the rat

The present study investigated the specific ways by which cytotoxicity due to glutamate receptor stimulation could be attenuated by the administration of agonists and antagonists of the ionotropic and metabotropic glutamate receptors within the nucleus basalis magnocellularis (NBM) of rats as measured by cortical choline acetyltransferase activity. The results of these studies suggest that (1) the cytotoxicity of ibotenate to NBM cholinergic cells is not dependent upon stimulation of metabotropic glutamate receptors, but results from activation of (NMDA) receptors, (2) the cytotoxicity of quisqualate to cholinergic cells within the NBM is not dependent upon stimulation of NMDA or metabotropic receptors, and (3) the cytotoxicity of NMDA was prevented by administration (i.p.) of the un-competitive NMDA antagonist memantine (30 mg/kg), resulting in plasma levels of 2.5 μg/ml, a concentration known to block efficiently NMDA receptors in vitro. Finally, performance of a food-motivated, delayed-alternation task on a T-maze was impaired by injections of NMDA into the NBM, but was prevented by co-administration of NMDA with memantine.     

微透析技术和丹参注射液对Wistar鼠脑缺血时海马细胞外液兴奋性氨基酸释放的影响

本文对微透析技术进行了方法学探讨，并应用该技术观察丹参注射液对脑缺血时Ｗｉｓｔａｒ鼠海马细胞外液氨基酸释放的影响。结果显示：脑缺血时丹参治疗组比缺血组及生理盐水组的海马细胞外液谷氨酸和天门冬氨酸明显减低（Ｐ＜０．０１），结合病理检查结果提示丹参注射液能减低脑缺血时海马细胞外液氨基酸的释放，并具有脑保护作用。微透析技术的应用为药物的研究提供新的方法。     

应激对大鼠海马谷氨酸、天冬氨酸和γ-氨基丁酸含量的影响

目的　探讨应激对大鼠海马谷氨酸、天冬氨酸和γ 氨基丁酸 (GABA)含量的动态影响。方法　将 72只健康雄性大鼠随机分为 5个应激暴露不同时间组和对照组 ,每组 12只。利用高效液相色谱仪 紫外检测法 ,分别于应激第 1,3,7,14和 2 8天观察应激对大鼠海马谷氨酸、天冬氨酸及GABA含量的影响。结果　应激第 1天组大鼠海马谷氨酸和天冬氨酸含量与对照组相比 ,差异无显著性 ;但GABA含量 [(2 74 7± 0 339) μmol/g]低于对照组 [(3 719± 0 5 2 8) μmol/g;P <0 0 5 ]。应激第 3,7,14和 2 8天组谷氨酸含量 [分别为 (7 818± 0 799) μmol/g ,(9 0 0 7± 0 5 2 0 ) μmol/g,(8 0 4 9± 0 733) μmol/g和 (8 12 9± 1 5 5 6 ) μmol/g]高于对照组 [(6 4 11± 0 6 38) μmol/g];天冬氨酸含量 [分别为 (2 717± 0 2 5 8)μmol/g,(2 6 96± 0 317) μmol/g,(2 82 8± 0 4 6 8) μmol/g和 (4 6 4 9± 0 6 37) μmol/g]也高于对照组 [(2 0 0 3± 0 2 71) μmol/g];均P <0 0 1。应激第 14天组和 2 8天组GABA含量 [分别为 (4 4 6 2± 0 883) μmol/g和(4 4 97± 0 85 7) μmol/g]高于对照组 (P <0 0 5～0 .0 0 1) ,应激第 3天组和 7天组的GABA含量与对照组间的差异无显著性。结论　应激第 3天开始     

A protective effect of lithium on rat behaviour altered by ibotenic acid lesions of the basal forebrain cholinergic system

Lithium was tested on an animal model of a brain cholinergic excitotoxic lesion. Male Wistar rats received unilaterally 50 nmol ibotenic acid in the nucleus basalis magnocellularis. Some were treated intraperitoneally with LiCl from two days before to six days after lesioning. Such treated rats showed less deficits than untreated lesioned animals on passive avoidance, ambulatory behaviour and choline acetyltransferase activity in the lesioned cortex. Lithium protection against excitatory amino acid neurotoxicity is suggested.     

Seizures induced by aminooxyacetic acid in mice: pharmacological characteristics

Systemic (s.c.) administration of aminooxyacetic acid (AOAA) in mice triggered clonic convulsions with a CD50 (convulsive dose) of 68 mg/kg (range 54-86). AOAA also induced clonic convulsions in mice subjected to intracerebroventricular administration of the drug with a CD50 of 0.04 mumols (range 0.028-0.06). At the onset of convulsions induced by systemic AOAA (CD97;150 mg/kg), the GAD activity in the frontal cortex and hippocampus was not affected. GABA mimetic drugs, progabide and gabaculine, had no effect on convulsions induced by AOAA. Convulsions induced by systemic administration of AOAA were blocked by diazepam, phenobarbital, and valproate. Ethosuximide, trimethadione, acetazolamide, diphenylhydantoin, and carbamazepine remained ineffective. L-Phenylisopropyladenosine was also found to protect mice against AOAA-induced convulsions, whereas atropine and baclofen had no effect. The seizures induced by intracerebroventricular administration of AOAA (CD97; 0.1 mumols) were blocked by coadministration of preferential N-methyl-D-aspartate antagonists, D-(-)-2-aminophosphonoheptanoic (AP7), 3-[+/-)-2-carboxypiperazine-4-yl)-propyl-1-phosphonic (CPP), and kynurenic acid (KYNA); preferential quisqualate/kainate antagonists, 6-cyano-7-nitro-quinoxaline-2,3-dione and gamma-D-glutamylaminomethylsulphonic acid, remained inactive in the range of dosages sufficient to block seizures induced by quisqualic acid or kainic acid. The antagonistic action of antiepileptic drugs effective against seizures induced by excitatory amino acids (diazepam and valproate), and drugs acting on excitatory amino acid receptors (AP7, CPP, and KYNA) upon seizures induced by AOAA suggests an involvement of excitatory neurotransmission in the convulsant action of the drug.     

Protective effect of nerve growth factor against glutamate-induced neurotoxicity in cultured cortical neurons

The effect of recombinant human nerve growth factor (hNGF) and mouse NGF on cultured rat cortical neurons was examined. The DNA fragment coding the human NGF gene was isolated and inserted downstream from the SV40 promoter in a plasmid containing the dihydrofolate reductase cDNA, and this plasmid was introduced into Chinese hamster ovary (CHO) cells to establish cells producing recombinant hNGF. The recombinant hNGF protein secreted by CHO cells was confirmed to be biologically active in an assay using PC12 cells. Brief exposure of cortical cells to glutamate followed by incubation with glutamate-free medium reduced cell viability by 60–70% when compared with the control culture. Simultaneous addition of recombinant hNGF or mouse NGF to rat cortical cultures with glutamate did not affect this reduction of cell viability. However, 24 h pretreatment of rat cortical cultures with recombinant hNGF or mouse NGF resulted in a significant reduction of glutamate-induced neuronal damage. Mouse NGF also protected cortical neurons against N-methyl-d-aspartate (NMDA)- and kainate-induced neuronal damage. These findings suggest that NGF can protect cortical neurons against glutamate-induced neurotoxicity.     

尼莫的平对Alzheimer病大鼠海马和额叶细胞外液氨基酸的影响

目的 研究尼莫的平对Ａｌｚｈｅｉｍｅｒ病大鼠海马和额叶兴奋性氨基酸的影响。方法 在立体定位下于迈内特基底核（ＮＢＭ）注入β淀粉样蛋白（β－ＡＰ）１０μｇ建立Ａｌｚｈｅｉｍｅｒ病模型,对照组在ＮＢＭ注入生理盐水,治疗组在建立模型后腹腔注射尼莫的平,每天注射１次至实验结束,模型组不给任何药物。脑内微透析技术采集大鼠海马、额叶细胞外液、反相高效液相色谱技术测定氨基酸类神经递质。结果 模型组海马和额叶细胞外液４种氨基酸浓度均较对照组升高,谷氨酸最明显。尼莫的平治疗后谷氨酸明显降低。结论 由β－ＡＰ产生的Ａｌｚｈｅｉｍｅｒ病大鼠痴呆与兴奋毒性有关,其作用可能是由钙离子介导。