三七总皂甙对脑出血大鼠前脑兴奋性氨基酸受体GluR2表达的作用

目的：研究三七总皂甙对脑出血大鼠前脑兴奋性氨基酸受体AMPA受体亚基GluR2表达的作用。方法：用免疫组织化学法观察胶原酶诱导的脑出血大鼠前脑内GluR2在给药组和对照组的表达变化。结果：脑出血后大鼠前脑病灶内部GluR2表达呈阴性,海马很少表达,但病灶周围和同侧皮质神经元的表达增强。给药组在皮层、病灶周围阳性细胞增多,反应强度增强。结论：三七总皂甙对GluR2阳性表达有增强作用,从而发挥对受损神经元的保护作用。     

氯喹对戊四氮慢性致痫大鼠海马GluR2及nNOS表达的影响

目的:观察氯喹对戊四氮慢性致痫大鼠海马α-氨基羟甲基异恶唑丙酸(amino-3-hydroxy-5-methylisox-azole-4-propionic acid,AMPA)受体(GluR2)及神经型一氧化氮合酶(nitric oxide synthase,nNOS)表达的影响,探讨氯喹在癫痫发生发展中的作用。方法:30只健康雄性SD大鼠,随机分为3组:对照组(10只)、戊四氮致痫组(10只)、氯喹干预组(10只),观察大鼠行为表现和脑电图的改变。应用Western Blot检测大鼠海马GluR2含量的改变,免疫组化检测nNOS的变化。结果:对照组无癫痫发作,戊四氮致痫组癫痫发作严重(III~Ⅴ级),氯喹干预组痫样发作与戊四氮致痫组相比较轻(Ⅰ~III级,P<0.05);戊四氮致痫组脑电记录呈频发高幅的痫样波,氯喹干预组痫样波幅低且缓;与对照组相比,癫痫组GluR2表达减弱(P<0.05),氯喹干预组与对照组比较差异有显著性(P<0.05);nNOS在戊四氮致痫组表达强,以海马为著,与对照组比较差异有显著性(P<0.05),氯喹干预组与对照组比较无显著性差异(P>0.05)。结论:氯喹可以通过调节GluR2的含量和抑制nNOS的表达,表明氯喹可能是预防和治疗癫痫的理想药物。     

炎症因子对原代培养海马神经元CLC-3表达的影响

目的:研究不同浓度TNF-α、IL-1β、TGF-β刺激对原代培养海马神经元CLC-3(voltage-gated chloride channel 3)mRNA及蛋白质水平的影响。方法:取原代培养8 d的大鼠海马神经元,随机分为对照组、TNF-α组、IL-1β组和TGF-β组。TNF-α、IL-1和TGF-β组分别加入加入含有浓度为10 ng/ml的相应炎症因子培养液,每组分别在孵育6、12、24 h后分别收集细胞提取总RNA和蛋白采用实时定量PCR、Western Blot技术检测CLC-3 mRNA及蛋白水平的表达。结果:TNF-α、IL-1β处理12 h后培养海马神经元CLC-3在mRNA及蛋白水平开始上调,高峰持续从12 h至24 h(P0.05)。TNF-α刺激作用强于IL-1β。TGF-β处理海马神经元CLC-3 mRNA在6 h后即开始升高(P0.05),但在孵育6 h到24 h时下降至正常对平(P0.05)。结论:TNF-α、IL-1β、TGF-β可能通过刺激海马神经元CLC-3表达增加增强神经元存活能力。     

新生大鼠海马神经元的体外原代培养

目的研究体外原代培养新生大鼠海马神经元的方法,并观察其发育分化过程中形态学的变化。方法取出生24 h内的Wistar大鼠分离海马,消化后差速贴壁,种植在涂有多聚-L-赖氨酸的盖玻片上,于不同时间在倒置相差显微镜下观察形态变化;采用NSE免疫细胞化学技术鉴定神经元。结果神经元12~24 h后大部分贴壁,随时间延长形态多变,突起逐渐增多,神经元突起间互相接触形成网络。培养第7~10天时细胞最为丰满,至28天时培养液中有悬浮的细胞碎片。NSE鉴定结果显示神经元纯度为(92.3±6.8)%。结论该方法简单易行,神经元纯度较高,可作为神经元体外培养的良好模型用于以后的研究。     

咖啡因对大鼠海马神经元形态学的影响

目的观察不同剂量咖啡因对大鼠海马神经元形态结构的影响。方法 30只雌性SD大鼠随机分成对照组、低剂量组和高剂量组,每天分别给予生理盐水、20mg/kg和60mg/kg咖啡因灌胃处理,连续18d。运用HE染色、尼氏染色和电镜进行观察。结果HE染色未见明显异常;尼氏染色显示,实验组尼氏体较对照组显著增多(P0.05),高剂量组尼氏体较低剂量组有所减少;电镜观察发现,实验组海马神经元内游离核糖体密度较对照组明显增高,高剂量组海马部分神经元局部内质网轻度扩张、线粒体肿胀、神经髓鞘松懈受损。结论咖啡因能够使大鼠尼氏体数量增加,但过高剂量会造成海马神经元超微结构损坏。     

低氧预处理对大鼠海马神经元缺氧耐受性和bcl-2表达的影响

采用免疫组织化学方法观察了低氧预处理对大鼠海马神经元缺氧耐受性和 bcl-2表达的影响。结果显示 ,经低氧预处理的海马神经元缺氧 -复氧后 bcl-2表达较对照组明显增强 ,神经元损伤程度减轻 ,神经元存活数明显高于对照组。本结果表明 ,低氧预处理可使海马培养神经元对缺氧产生耐受 ,增加缺氧 -复氧后神经元 bcl-2的表达。提高神经元存活数     

Bcl-2抑制剂对黄芪注射液降低缺氧缺糖/复氧复糖大鼠海马神经元caspase-3表达的影响

目的:观察Bcl-2抑制剂对黄芪注射液降低缺氧缺糖/复氧复糖大鼠海马神经元caspase-3表达的影响。方法:取体外原代培养8 d的海马神经元,随机分为6组:正常对照组、模型组(缺氧缺糖/复氧复糖组)、黄芪注射液组、黄芪注射液溶剂(无菌去离子水)对照组、Bcl-2抑制剂组和Bcl-2抑制剂+黄芪注射液组。除正常对照组外均进行缺氧缺糖0.5 h再复氧复糖,各组均于复氧复糖后24 h进行指标检测:采用细胞免疫化学染色法观察细胞形态和caspase-3阳性细胞率,Western blotting法检测海马神经元Bcl-2和cleaved caspase-3蛋白的表达,RTPCR法检测海马神经元caspase-3 mRNA的表达。结果:与正常对照组相比,模型组细胞caspase-3阳性率、Bcl-2、cleaved caspase-3蛋白及caspase-3 mRNA表达均明显增强(P0.05);与模型组相比,黄芪注射液组Bcl-2表达明显增加,细胞caspase-3阳性率、cleaved caspase-3蛋白及caspase-3 mRNA表达均明显降低(P0.05);而黄芪注射液溶剂对照组、Bcl-2抑制剂组及Bcl-2抑制剂+黄芪注射液组则无明显差异;黄芪注射液溶剂对照组Bcl-2表达较正常对照组无明显变化,而Bcl-2抑制剂组及Bcl-2抑制剂+黄芪注射液组显著下降(P0.05)。结论:Bcl-2抑制剂可对抗黄芪注射液降低缺氧缺糖/复氧复糖大鼠海马神经元caspase-3表达的作用,黄芪注射液通过Bcl-2发挥对缺氧缺糖/复氧复糖大鼠海马神经元凋亡的抑制作用。     

胰岛素对糖尿病大鼠海马内神经营养因子-3阳性神经元表达的影响

目的：观察糖尿病大鼠海马中神经营养因子-3(NT-3)的表达变化及胰岛素治疗对其表达的影响。方法：将雄性大鼠随机分为对照组,糖尿病1,3月组,胰岛素治疗1,3月组,STZ 腹腔注射制模,测体重与血糖值并取海马行 HE 和免疫组化 SABC 法染色,计算机图像分析系统测平均光密度值。结果：血糖在糖尿病组比对照组显著升高;胰岛素组与对照组无显著性差异。海马各区 NT-3免疫阳性神经元的数量及阳性强度在糖尿病组有不同程度降低,以 CA1区最明显。胰岛素组则不降低。结论：糖尿病大鼠海马神经元 NT-3表达减弱,胰岛素治疗可使海马神经元 NT-3表达恢复正常。     

丹酚酸B对培养的新生大鼠海马神经元的影响

目的:本研究旨在观察丹酚酸B对体外培养新生大鼠海马神经元的影响,为丹酚酸B对中枢神经系统的作用提供实验依据。方法:体外培养新生大鼠海马神经元,神经元微管相关蛋白-2(MAP-2)免疫荧光染色对培养细胞进行鉴定,实验分为对照组和给药组(终浓度分别为5 mg/L和10 mg/L),荧光显微镜下观察细胞形态,MTT比色法检测丹酚酸B对海马神经细胞的活性,细胞核染色(DAPI)观察丹酚酸B对海马神经细胞增殖的影响。结果:免疫荧光染色显示细胞呈MAP-2阳性,丹酚酸B作用7 d后,能明显促进海马神经细胞的存活与增殖,且10 mg/L的丹酚酸B作用更明显。结论:丹酚酸B能明显促进海马神经细胞的存活与增殖,提示其具有改善脑功能的重要作用。     

大鼠海马CA3区胆碱能神经元的衰老变化

目的:探讨大鼠海马CA3区胆碱能神经元增龄性变化的规律.方法:SD大鼠随机分为1～2月龄、4～5月龄,11～12月龄、≥24月龄4组,常规石蜡包埋海马连续冠状切片,尼氏染色、乙酰胆碱转移酶(ChAT)免疫组织化学显色,图像分析仪测量ChAT免疫反应阳性产物的光密度及其阳性神经元的多种形态学参数.结果:随着年龄的增长,大...     

A subpopulation of serotonin1B receptors colocalize with the AMPA receptor subunit GluR2 in the hippocampal dentate gyrus

The serotonin_1B receptor (5-HT_1BR) plays a role in cognitive processes that also involve glutamatergic neurotransmission via amino-3-hydroxy-5-methyl-4-isoxazoleproprionic acid (AMPA) receptors. Accumulating experimental evidence also highlights the involvement of 5-HT_1BRs in several neurological disorders. Consequently, the 5-HT_1BR is increasingly implicated as a potential therapeutic target for intervention in cognitive dysfunction. Within the hippocampus, a brain region critical to cognitive processing, populations of pre- and post-synaptic 5-HT_1BRs have been identified. Thus, 5-HT_1BRs could have a role in the modulation of hippocampal pre- and post-synaptic conductance. Previously, we demonstrated colocalization of 5-HT_1BRs with the N-methyl-d-aspartate (NMDA) receptor subunit NR1 in a subpopulation of granule cell dendrites (Peddie et al. [53]). In this study, we have examined the cellular and subcellular distribution of 5-HT_1BRs with the AMPA receptor subunit GluR2. Of 5-HT_1BR positive profiles, 28% displayed colocalization with GluR2. Of these, 87% were dendrites, corresponding to 41% and 10% of all 5-HT_1BR labeled or GluR2 labeled dendrites, respectively. Dendritic labeling was both cytoplasmic and membranous but was not usually associated with synaptic sites. Colocalization within dendritic spines and axons was comparatively rare. These findings indicate that within the dentate gyrus molecular layer, dendritic 5-HT_1BRs are expressed predominantly on GluR2 negative granule cell processes. However, a subpopulation of 5-HT_1BRs is expressed on GluR2 positive dendrites. Here, it is suggested that activation of the 5-HT_1BR may play a role in the modulation of AMPA receptor mediated conductance, further supporting the notion that the 5-HT_1BR represents an interesting therapeutic target for modulation of cognitive function.     

AMPA receptor GluR2, but not GluR1, subunit deletion impairs emotional response conditioning in mice

Deletions of gria1 or gria2 genes encoding alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic-acid-receptor subunits differ in their effects on appetitive conditioning. The authors investigated whether similar differences would occur in an aversive conditioning test. The ability of a discrete stimulus paired with footshock to subsequently inhibit food-maintained operant responding (conditioned emotional response) was examined in mice with deletions of gria1 or gria2 genes. Whereas gria1 knockout (KO) mice performed normally compared with wild-type (WT) controls, gria2 KO mice displayed no reduction in response rates when the shock-paired stimulus was presented. Nevertheless, gria2 KOs displayed evidence of freezing in a footshock-paired context, indicating that aversive learning could occur. In addition, gria1 KO mice showed some evidence of increased anxiety, and gria2 KOs showed reduced anxiety, in the elevated plus-maze.     

补阳还五汤对血管性痴呆大鼠海马GluR1蛋白及mRNA表达的影响

目的:观察补阳还五汤对血管性痴呆(VD)大鼠海马α-氨基羟甲基恶丙酸受体(AMPA)GluR1亚单位蛋白及mRNA表达的影响,探讨补阳还五汤治疗VD的机制。方法:四血管阻断法制备VD大鼠模型。设立假手术组、VD模型组、尼莫地平组(20mg·kg-1.d-1,灌胃30d)和补阳还五汤治疗组(50g·kg-1.d-1灌胃30d)。Morris水迷宫检测大鼠学习记忆能力的改变,免疫组化和Westernb lotting技术检测大鼠海马神经元GluR1蛋白的变化,实时荧光定量PCR技术检测大鼠海马GluR1mRNA表达的变化。结果:与假手术组相比,VD模型组大鼠逃避潜伏期延长和平均探索次数减少(P0.05);补阳还五汤明显改善了模型大鼠上述学习、记忆成绩(P0.05);假手术组、尼莫地平组与补阳还五汤治疗组之间差异无显著(P0.05)。VD模型组大鼠的GluR1蛋白及其mRNA表达水平较假手术组明显降低(P0.05);补阳还五汤治疗组大鼠海马的GluR1蛋白及其mRNA表达水平较模型组的表达明显升高(P0.05);假手术组、尼莫地平组与补阳还五汤治疗组之间差异无显著(P0.05)。结论:补阳还五汤可以改善VD大鼠学习记忆能力,其机制可能与减轻脑缺血再灌注对海马CA1区神经元的损伤及恢复海马组织GluR1蛋白及其mRNA的表达有关。     

Effect of sodium hydroxybutyrate on the expression of hippocampal N-methyl-D-aspartate receptor 2B subunit mRNA in neonatal rats with hypoxic-ischemic insult

The objective of this research was to test whether sodium hydroxybutyrate (GHB-Na) protects rat neonatal brain against hypoxia-ischemia (HI). Specifically, the objective was to determine the effect of GHB-Na administration on the expression of N-methyl-D-aspartate subunit (NR2B) mRNA in the rat hippocampus. Seven-day-old Sprague-Dawley rats were subjected to ligation of the left carotid artery and were randomly assigned to 5 groups: sham operated (S), saline treated (C), and those treated with GHB-Na (G1, G2, G3), at 3 dosages (50, 100, or 200 mg/kg, ip, thrice daily). NR2B mRNA levels in the left hippocampus were assayed at 2, 6, 12, 24, 72, and 168 hr after HI (exposure to 8% O(2)/92% N atmosphere for 2 hr). The results suggest that HI insult increased NR2B mRNA gene expression in the left hippocampus of the neonatal rats and that GHB-Na administration partially suppressed this effect of HI insult.     

Immunocytochemical localization of the AMPA glutamate receptor subtype GluR2/3 in the squid optic lobe

As a major excitatory neurotransmitter in the cephalopod visual system, glutamate signaling is facilitated by ionotropic receptors, such as α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors (AMPAR). In cephalopods with large and well-developed brains, the optic lobes (OL) mainly process visual inputs and are involved in learning and memory. Although the presence of AMPAR in squid OL has been reported, the organization of specific AMPAR-containing neurons remains unknown. This study aimed to investigate the immunocytochemical localization of the AMPA glutamate receptor subtype 2/3-immunoreactive (GluR2/3-IR) neurons in the OL of Pacific flying squid (Tordarodes pacificus). Morphologically diverse GluR2/3-IR neurons were predominantly located in the tangential zone of the medulla. Medium-to-large GluR2/3-IR neurons were also detected. The distribution patterns and cell morphologies of calcium-binding protein (CBP)-IR neurons, specifically calbindin-D28K (CB)-, calretinin (CR)-, and parvalbumin (PV)-IR neurons, were similar to those of GluR2/3-IR neurons. However, two-color immunofluorescence revealed that GluR2/3-IR neurons did not colocalize with the CBP-IR neurons. Furthermore, the specific localizations and diverse types of GluR2/3-IR neurons that do not express CB, CR, or PV in squid OL were determined. These findings further contribute to the existing data on glutamatergic visual systems and provide new insights for understanding the visual processing mechanisms in cephalopods.     

Dominant role of the GluR2 subunit in regulation of AMPA receptors by CaMKII

GluR1 and GluR2 subunits compose AMPA receptors (AMPARs) in the mature hippocampus, and both the GluR1 subunit and Ca2+/calmodulin-dependent protein kinase II (CaMKII) are required for synaptic plasticity, memory and learning. Although GluR1 phosphorylationby CaMKII is preserved, the functional regulation of AMPARs by phosphorylation is lost in the presence of the GIuR2 subunit. Our findings define a previously unknown, dominant role of the GluR2 subunit in signaling mediated by CaMKII at AMPARs.     

Use-dependent AMPA receptor block in mice lacking GluR2 suggests postsynaptic site for LTP expression

The mechanisms responsible for enhanced transmission during long-term potentiation (LTP) at CA1 hippocampal synapses remain elusive. Several popular models for LTP expression propose an increase in 'use' of existing synaptic elements, such as increased probability of transmitter release or increased opening of postsynaptic receptors. To test these models directly, we studied a GluR2 knockout mouse in which AMPA receptor transmission is rendered sensitive to a use-dependent block by polyamine compounds. This method can detect increases during manipulations affecting transmitter release or AMPA receptor channel open time and probability, but shows no such changes during LTP. Our results indicate that the recruitment of new AMPA receptors and/or an increase in the conductance of these receptors is responsible for the expression of CA1 LTP.     

GluR2/3 label expression of the AMPA-type glutamate receptor in the hippocampal formation of the homing pigeon stabilizes just after birth

The compositions of the glutamate AMPA-type receptors influence the neural response and the subunits GluR2/3 has been referred to as essential for receptor trafficking and synapse consolidation. We investigate the GluR2/3 occurrence and expression in the hippocampal formation of newly born homing pigeons by a semi-quantitative approach, the Western-blotting technique and by immunohistochemistry. Immunoreactivity for GluR2/3 occurs before hatching has been evident in neuropil that was fully dispersed over the hippocampus proper (HP) and the area parahippocampalis (APH). Although many HP cells are NeuN-positives, a specific neuronal protein indicating that they are already differentiated as neurons while not one contains GluR2/3 at the hatching day (P0). Few neurons at the APH seem to express GluR2/3 at P0, but 3 days later (P3) the GluR2/3 labeling can be recognized in many HP neurons, showing a distribution pattern that resembles the adult, gradually increasing in intensity until P10. Also, the Western-blot shows an augment between P0 and P3, remaining stable after that. The enhancement of the neuronal label at P3 coincides with the retraction of the GluR2/3 label in neuropil, reducing their occurrence during the maturational period to become restricted to the dorsomedial portion as reported for adults. As the HP GluR2/3-containing cells are supposedly projecting neurons, taking together, the results signalize the relevance of the GluR2/3 in post-hatch formation of avian hippocampal circuitry in which the third day seems to be the critical period.     

Gadolinium reduces AMPA receptor desensitization and deactivation in hippocampal neurons.

The actions of the trivalent cation Gd(3+) on whole cell AMPA receptor-mediated currents were studied in isolated hippocampal neurons, in nucleated or outside-out patches taken from cultured hippocampal neurons, and on miniature excitatory postsynaptic currents (mEPSCs) recorded in cultured hippocampal neurons. Glutamate, AMPA, or kainate was employed to activate AMPA receptors. Applications of relatively low concentrations of Gd(3+) (0.1-10 microM) substantially enhanced steady-state whole cell glutamate and kainate-evoked currents without altering peak currents, suggesting that desensitization was reduced. However, higher concentrations (>30 microM) depressed steady-state currents, indicating an underlying inhibition of channel activity. Lower concentrations of Gd(3+) also increased the potency of peak glutamate-evoked currents without altering that of steady-state currents. An ultrafast perfusion system and nucleated patches were then used to better resolve peak glutamate-evoked currents. Low concentrations of Gd(3+) reduced peak currents, enhanced steady-state currents, and slowed the onset of desensitization, providing further evidence that this cation reduces desensitization. In the presence of cyclothiazide, a compound that blocks desensitization, a low concentration Gd(3+) inhibited both peak and steady-state currents, indicating that Gd(3+) both reduces desensitization and inhibits these currents. Gd(3+) reduced the probability of channel opening at the peak of the currents but did not alter the single channel conductance calculated using nonstationary variance analysis. Recovery from desensitization was enhanced, and glutamate-evoked current activation and deactivation were slowed by Gd(3+). The Gd(3+)-induced reduction in desensitization did not require the presence of the GluR2 subunit as this effect was seen in hippocampal neurons from GluR2 null-mutant mice. Gd(3+) reduced the time course of decay of mEPSCs perhaps as a consequence of its slowing of AMPA receptor deactivation although an increase in the frequency of mEPSCs also suggested enhanced presynaptic release of transmitter. These results demonstrate that Gd(3+) potently reduces AMPA receptor desensitization and mimics a number of the properties of the positive modulators of AMPA receptor desensitization such as cyclothiazide.