代谢型谷氨酸受体与癫痫

兴奋性神经递质谷氨酸与谷氨酸受体结合 ,在癫痫的发病中发挥重要作用。对谷氨酸受体的研究表明 ,谷氨酸受体存在两种类型 [1 ] :离子型谷氨酸受体(intropic glutamate receptors,i Glu Rs)和代谢型谷氨酸受体 (metabotropic glu-tam ate receptors,m Glu Rs )。前者包括NMDA、     

代谢型谷氨酸受体与癫痫

代谢型谷氨酸受体是一类与G-蛋白偶联的调节离子通道和第二信使生成酶的特异受体,随着不同亚型的相继克隆以及功能的逐步阐明,其与神经系统疾病的关系引起了研究者的广泛兴趣。本文对代谢型谷氨酸受体各亚型在癫痫发作中的作用及其机制作一综述。     

局灶脑缺血大鼠代谢型谷氨酸受体5mRNA表达及意义

目的观察局灶脑缺血大鼠脑组织中代谢型谷氨酸受体5mRNA(metabotropic glutamate receptor 5,mGluR5 mRNA)在脑缺血不同时段的表达及其动态变化的规律,探讨其在急性脑缺血中变化的意义。方法55只雄性Wistar大鼠随机分为正常对照组、脑缺血1、3、6、12及24h组(手术组)及其相对应的假手术对照组,采用线栓法制备大鼠MCAO模型,至上述规定时间点后取大脑组织,利用地高辛标记寡聚核苷酸探针原位杂交技术判断神经元阳性表达的强弱,用计算机图像分析系统检测各组mGluR5 mRNA表达的灰度值及阳性细胞数。结果各手术组mGluR5 mRNA表达均高于假手术对照组及正常对照组,与正常对照组相比,缺血1h其表达即有升高,至6h达高峰。而假手术对照组与正常对照组相比无统计学意义。结论急性脑缺血可引起mGluR5 mRNA表达上调,提示mGluR5参与了局灶性脑缺血损伤,可能促进了缺血性脑血管病的发展。     

亚低温对体外缺氧缺糖损伤后神经元的保护作用及其对谷氨酸转运体、亲代谢型谷氨酸受体表达的影响

目的通过研究亚低温对体外缺氧缺糖损伤的神经细胞谷氨酸转运体(GLT-1)、亲代谢型谷氨酸受体(mGluR2/3)表达的影响,探讨亚低温的神经保护途径。方法分组培养大鼠大脑皮层细胞,亚低温组在33 C条件、常温组在37 C条件,缺氧缺糖培养2h后,复氧复糖37 C培养,经时(6h、12h、24h、3d)检测LDH释放量、GLT-1和mGluR2/3蛋白表达量。结果在复氧复糖后,两组LDH释放均呈现上升趋势,其中24h和3d亚低温组的LDH上升水平显著降低(P<0.05);两组GLT-1表达均呈现先下降后上升的趋势,其中6h和12h亚低温组的GLT-1下降水平显著降低(P<0.05);两组mGluR2/3表达均呈现上升趋势,其中12h和24h亚低温组的mGluR2/3升高水平显著增加(P<0.05)。结论亚低温能够在体外水平,通过抑制GLT-1蛋白的表达下调,促进mGluR2/3的表达上调,抑制神经元兴奋性损伤。     

弥漫性脑损伤后代谢型谷氨酸受体亚型4及其激动剂L-AP 4的作用

目的　研究弥漫性脑损伤 (DBI)后大鼠脑皮质代谢型谷氨酸受体亚型 4 (mGluR 4 )及其激动剂L 2 氨基 4 膦酰基丁酸(L AP 4 )的变化及意义。方法　 16 1只SD大鼠随机分为两组。A组包括正常对照组、假手术组及DBI组。用Marmarou弥漫性脑损伤模型 ,制成DBI模型 ,于伤后不同时间进行mGluR 4mRNA原位杂交。B组包括单纯、DBI后生理盐水治疗及DBI后L AP 4治疗组。所有DBI动物伤前进行行为学训练。伤后 1h、12h脑室内分别给予L AP 4 (10 0mM ,10 μl)或生理盐水。大鼠在伤后 1、3、7、14d分批处死前进行运动和行为学检查 ,处死后检测神经元损伤数。结果　与正常对照组相比 ,假手术组阳性神经元数无改变 (P >0 .0 5 ) ;与假手术组相比 ,单纯DBI组mGluR 4mRNA表达于脑损伤后 1h即有明显增加(P <0 .0 1) ,在 6h达到高峰。与DBI后生理盐水治疗组比较 ,DBI后L AP 4治疗组神经元损伤数减少 ,神经功能检查指数增高。结论　mGluR 4参与了DBI的病理生理过程 ,具有神经保护作用。     

代谢型谷氨酸受体及其拮抗剂MCPG对弥漫性脑损伤大鼠的影响

目的:观察代谢型谷氨酸受体拮抗剂MCPG对弥漫性脑损伤大鼠的影响。方法:使用Marmarou的动物模型,55只动物分为对照、损伤和MCPG组。给予MCPG组立体定向脑室注射MCPG lumol/5ul。分别在伤后1、4、8、12、24小时测定脑组织含水量、递质性氨基酸(Glu、GABA)及离子Ca~(2+)、Mg~(2+)含量。结果:伤后脑组织含水量、GABA、Ca~(2+)升高,Glu、Asp及Mg~(2+)含量下降。MCPG组较损伤组各项指标均有明显的好转。结论:MCPG能有效的抑制代谢型谷氨酸受体激活导致的继发性损害。     

PACAP对谷氨酸引起海马神经元损伤的保护作用

目的研究垂体腺苷酸环化酶激活肽（ＰＡＣＡＰ）对谷氨酸引起的海马神经元损伤的保护作用及其受体机制。方法海马神经元体外培养７ｄ,给予谷氨酸。结果当谷氨酸是０．１～１．０ｍｍｏｌ／Ｌ时,随着剂量的增加,神经元的存活率逐渐降低;１０－９ｍｏｌ／Ｌ～１０－１３ｍｏｌ／Ｌ的ＰＡＣＡＰ,能减轻谷氨酸引起的海马神经元损伤;ＰＡＣＡＰⅠ型受体特异性拮抗剂ＰＡＣＡＰ６－３８能抑制ＰＡＣＡＰ减轻谷氨酸对海马神经元损伤作用。结论ＰＡＣＡＰ具有减轻谷氨酸引起的海马神经元损伤的作用,该作用是由ＰＡＣＡＰⅠ型受体介导的。     

代谢型谷氨酸受体及其与神经变性疾病

代谢型谷氨酸受体的发现是谷氨酸能突触传递研究中的一项重要进展,其激活后通过胞内不同的信号转导系统,既能发挥保护性作用,又能发挥神经毒性作用.着重讨论了代谢型谷氨酸受体的分类、各组亚型的功能以及与神经变性疾病的关系.     

亲代谢型谷氨酸受体与帕金森病相关性研究进展

帕金森病 (ＰＤ)的病因和发病机制至今仍未阐明[1] 。国外近期的统计资料表明 ,ＰＤ发病率占总人数的 0 .1%～ 0 .2 % ,其中 5 5岁以上人口占 1.4 % [2 ] 。社会老龄化使得ＰＤ发病率呈明显上升趋势。目前认为ＰＤ的发生是由于中脑多巴胺(ＤＡ)能神经元选择性退变 ,并且残存的ＤＡ能神经元中出现一定数量的嗜酸性包涵体。黑质致密区 (ＳＮｃ)ＤＡ能神经元缺失 ,最终导致间接通路活性的增强 ,尤其是丘脑底核 (ＳＴＮ)谷氨酸 (Ｇｌｕ)能神经元的活性 ,而出现锥体外系病变。手术治疗旨在减弱间接通路活性的传导 ,但其侵害性大、费用昂贵 ,只适…     

Ⅰ型代谢型谷氨酸受体与癫(癎)

在哺乳动物的中枢神经系统中,谷氨酸是调节绝大多数神经突触兴奋性的主要神经递质。这种调节作用主要是通过激活以下受体来实现的,配基门控离子通道型谷氨酸受体(iGluR,简称离子通道型谷氨酸受体)和代谢调节型谷氨酸受体(mGluR,简称代谢型谷氨酸受体)。离子通道型谷氨酸受体分     

Metabotropic glutamate receptor antagonists and agonists: Potential neuroprotectors in diffuse brain injury

Our previous study has suggested that metabotropic glutamate receptors (mGluRs) were significantly involved in the secondary processes after diffuse brain injury (DBI) and that mGluRs antagonists or agonists may be used for the treatment of DBI. In the present study, the neuroprotective effects of antagonists or agonists of mGluRs on DBI were further investigated. Sprague-Dawly rats were randomized into the following six groups: (i) normal control; (ii) sham-operated control; (iii) DBI; (iv) DBI treated with normal saline (NS); (v) DBI treated with alpha-methyl-4-carboxy-phenylglycine (MCPG); and (vi) DBI treated with (2S,1'R,2'R,3'R)-2-(2,3-dicarboxycyclopropyl)glycine (DCG-IV). Animals were injected intracerebroventricularly (icv) with 10 microL MCPG (100mmol/L), DCG-IV (10nmol/L) or the equivalent volume of normal saline 1 h after injury. The neurological severity score (NSS), brain water content and the number of damaged neurons were determined 6, 12, 24, 72 and 168 h after injury. In rats with DBI, it was found that the NSS was improved and the water content in the frontal cortex and the number of damaged neurons in the parietal cortex were significantly reduced following icv injection of either MCPG or DCG-IV. This suggests that icv injection of the mGluR group I antagonist MCPG or the mGluR group II agonist DCG-IV may exert neuroprotective effects in the early stage after DBI.     

Novel mGluR5 Positive Allosteric Modulator Improves Functional Recovery,Attenuates Neurodegeneration,and Alters Microglial Polarization after Experimental Traumatic Brain Injury

Traumatic brain injury (TBI) causes microglial activation and related neurotoxicity that contributes to chronic neurodegeneration and loss of neurological function. Selective activation of metabotropic glutamate receptor 5 (mGluR5) by the orthosteric agonist (RS)-2-chloro-5-hydroxyphenylglycine (CHPG), is neuroprotective in experimental models of TBI, and has potent anti-inflammatory effects in vitro. However, the therapeutic potential of CHPG is limited due to its relatively weak potency and brain permeability. Highly potent, selective and brain penetrant mGluR5 positive allosteric modulators (PAMs) have been developed and show promise as therapeutic agents. We evaluated the therapeutic potential of a novel mGluR5 PAM, VU0360172, after controlled cortical impact (CCI) in mice. Vehicle, VU0360172, or VU0360172 plus mGluR5 antagonist (MTEP), were administered systemically to CCI mice at 3 h post-injury; lesion volume, hippocampal neurodegeneration, microglial activation, and functional recovery were assessed through 28 days post-injury. Anti-inflammatory effects of VU0360172 were also examined in vitro using BV2 and primary microglia. VU0360172 treatment significantly reduced the lesion, attenuated hippocampal neurodegeneration, and improved motor function recovery after CCI. Effects were mediated by mGluR5 as co-administration of MTEP blocked the protective effects of VU0360172. VU0360172 significantly reduced CD68 and NOX2 expression in activated microglia in the cortex at 28 days post-injury, and also suppressed pro-inflammatory signaling pathways in BV2 and primary microglia. In addition, VU0360172 treatment shifted the balance between M1/M2 microglial activation states towards an M2 pro-repair phenotype. This study demonstrates that VU0360172 confers neuroprotection after experimental TBI, and suggests that mGluR5 PAMs may be promising therapeutic agents for head injury.

Electronic supplementary material

The online version of this article (doi:10.1007/s13311-014-0298-6) contains supplementary material, which is available to authorized users.     

Metabotropic glutamate receptor mGluR5 is not involved in the early hemodynamic response

Activation of astrocytic metabotropic glutamate receptor 5 (mGluR5) is postulated to elicit calcium transients, triggering a chain of events that ultimately regulates cerebral blood flow by changing the tone of smooth muscle cells of nearby arterioles. Using concurrent in vivo optical imaging and determination of receptor occupancy with ¹¹C-ABP688, we report here that blocking ∼80% of mGluR5 in vivo does not affect transient hemodynamic responses on brief whisker stimulations while transiently reducing neuronal activity as measured by voltage-sensitive dye imaging. Our results show that mechanisms other than activation of mGluR5 are required to trigger the initial hemodynamic response in normal physiological conditions.     

Reduced stress-induced hyperthermia in mGluR5 knockout mice

It hs been suggested that metabotropic glutamate receptor subtype 5 (mGluR5) play a role in the expression of anxiety, based on anxiolytic-like effects of the selective mGluR5 antagonist MPEP (2-methyl-6-(phenylethynyl)pyridine) in rodent models of anxiety, including stress-induced hyperthermia (SIH). To examine the suggested role of mGlu5 receptors in the expression of anxiety, we examined the stress response in mice lacking mGluR5 in several variations of the SIH procedure. In this paradigm, stress causes a mild increase in body temperature that can be blocked by known anxiolytic agents. Three procedures were employed: classical SIH using rectal-probe measurement of body temperature, and radiotelemetric measurement of body temperature in response to either saline injection or to the introduction of an intruder into the home cage. In all three procedures the mGluR5-knockout mice displayed a significant attenuation of the hyperthermic response to stress compared to littermate wild-type control mice. To confirm that our observations were likely to be due to the absence of mGluR5 in the knockout mice we also tested the effect of the recently described selective mGluR5 antagonist MTEP (3-[(2-methyl-1,3-thiazol-4-yl)ethynyl]pyridine) in both the wild-type and mGluR5 knockout mice. Administration of MTEP in the wild-type mice, but not the mGluR5 knockout mice, attenuated SIH. That the mGluR5 knockout mice displayed an anxiolytic-like phenotype and that the mGluR5 antagonist, MTEP, showed a anxiolytic-like effect only in mice possessing mGluR5 further supports the suggestion that mGluR5 antagonists may be useful in the treatment of anxiety.     

锌对脑外伤后神经元中泛素化蛋白表达的影响

目的 研究脑外伤(TBI)后锌和泛素化蛋白在神经元中的变化,探讨锌在脑外伤后继发性神经损伤中的作用机制.方法 建立重物坠落致脑外伤动物模型,应用ZP4荧光染色、Western blot法分别观察神经元中锌及泛素化蛋白变化,用Nissle染色检测神经元存活数目;最后在脑外伤患者挫伤区神经元中分别用AMG染色、Western blot法分别检测锌及泛素化蛋白变化.结果 ZP4荧光染色、Western blot法和Nissle染色发现脑外伤可诱导大鼠海马神经元中锌聚集、泛素化蛋白升高以及最终导致神经元损伤;而阻断锌聚集可减少神经元中泛素化蛋白的升高,并产生神经保护作用.最后,在人脑外伤挫伤区神经元中,应用AMG染色和Western blot法也检测到了明显锌聚集和泛素化蛋白的升高.结论 脑外伤后锌稳态的失衡可以影响蛋白质的降解并最终导致神经元的损伤.     

Effects of mGluR5 and mGluR1 antagonists on anxiety-like behavior and learning in developing rats

Antagonists of group I metabotropic receptors exhibit anxiolytic action in adult rats. In immature animals we demonstrated anticonvulsant action of MPEP and AIDA, antagonists of group 5 and group 1, respectively. However, there are no developmental data on anxiolytic-like and learning actions of both compounds.This study investigated whether the anticonvulsant dose range of MPEP and AIDA affects anxiety-like behavior and learning ability in immature rats.Animals at 12, 18 and 25 postnatal (P) days received MPEP in doses of 10, 20 or 40 mg/kg i.p., AIDA in doses of 10 or 20 mg/kg i.p. In P18 and P25 rats anxiety-like behavior and locomotor activity were tested in the light–dark box and open-field test at 15 (1st session) and 60 (2nd session) minutes after drug administration. Learning ability of P12, P18, and P25 animals was examined in the homing response test 15 min after drug administration.Both antagonists exhibited anxiolytic-like action in the 1st session, effects in the 2nd session were less marked. In the open-field test both antagonists increased locomotion only in P18 animals. Age-dependent changes were found in the homing response test, the return latency being longer only in P12 animals. While MPEP in doses of 20- and 40-mg/kg in P12 and 40-mg/kg in P18 rats prolonged the homing response, AIDA did not affect the homing behavior.Both MPEP and AIDA exert anxiolytic-like effect also in immature rats. Except for the youngest animals no changes in learning ability in the homing response test were found.     

人mGluR1基因mRNA实时荧光定量PCR方法的建立

目的建立代谢型谷氨酸受体1(mGluR1)基因mRNA表达水平的Taq Manreal-time PCR检测方法。方法以β-actin为内参基因,根据GenBank中人mGluR1及β-actin基因序列,分别设计了两套特异性引物和TaqMan探针,接着对反应的退火温度、引物浓度、探针浓度、Mg2 浓度进行优化,然后以优化的条件建立相对定量标准曲线,并对该方法的稳定性进行分析。结果mGluR1及β-actin基因的real-time PCR扩增效率分别为99.7%和100.0%;相对定量标准曲线的CT值线性范围分别为8.1～30.9和11.9～32.1,相关系数分别为0.999及1.000;批内及批间变异系数<6.4%。结论本研究所建立的针对mGluR1 mRNA表达水平的Taqman real-time PCR检测方法具有扩增效率高、稳定性好等特点,为进一步探索mGluR1的功能及其mRNA表达水平的变化和各种疾病发生、发展的相关性提供了方法学基础。     

Distribution of mGluR1alpha and mGluR5 immunolabeling in primate prefrontal cortex

Metabotropic glutamate receptors (mGluRs) mediate important modulatory glutamatergic influences throughout the brain. However, the specific localization and functions of group I mGluR subtypes (mGluR1alpha and mGluR5) in cortical neurotransmission are not well known, particularly in primates. To address this issue, we used immunoelectron microscopy to compare the subcellular localizations of mGluR1alpha and mGluR5 in the prefrontal cortex of macaque monkeys. Both receptor subtypes were found in a variety of subcellular compartments, including spines, dendrites, preterminal axons, axon terminals, and glia; however, quantitative differences were found in the relative abundance of labeled elements for each receptor. The mGluR1alpha-immunoreactive (-IR) elements were overwhelmingly the spines and dendrites, with labeled terminals, axons, and glia seen more rarely. The mGluR5-IR elements were also mostly spines and dendrites, but the proportion of labeled unmyelinated axons, terminals, and glia was higher than for mGluR1alpha-IR elements. Double labeling with SMI-32 and parvalbumin confirmed that both receptors were found in pyramidal cell and interneuron dendrites. The localization of mGluR1alpha to pyramidal cells in primate cortex contrasts with reports that mGluR1alpha is found almost exclusively in interneurons in rodent cortex. By using double labeling, we found no evidence for mGluR1alpha or mGluR5 in dopaminergic afferents to prefrontal cortex. The data presented here provide an anatomical substrate for a differential role of mGluR1alpha and mGluR5 in post-and presynaptic actions of glutamate in primate prefrontal cortex. They further suggest differences in the cortical distribution of group I mGluRs between primates and rodents.