HSV转基因表达IL-1ra抑制P77PMC大鼠的惊厥发作

利用PCR基因克隆及基因转染技术 ,构建含人IL 1ra(IL 1receptorantago nist,IL 1ra)cDNA的质粒型单纯疱疹病毒 (herpessimplexvirus ,HSV)载体 ,再由HSV 1tsK株包装成假病毒颗粒 ,然后注入P77PMC听源性惊厥易感大鼠侧脑室 ,观察LacZ基因和IL 1ra在脑内的表达情况及对P77PMC大鼠惊厥程度的影响 .结果表明 :( 1 )LacZ在脑内神经和非神经细胞可持续表达 8周以上 ;( 2 )侧脑室注射pHSV IL 1ra假病毒可明显抑制P77PMC大鼠的惊厥发作 .原位杂交和免疫荧光染色发现脑膜和脉络丛上皮细胞及某些神经细胞有IL 1ramRNA和蛋白的表达 .结果表明HSV载体可有效地将IL 1ra基因转入脑内 ,并能明显抑制P77PMC听源性惊厥易感大鼠的惊厥发作 .     

听源性惊厥致P77PMC大鼠杏仁核内胆囊收缩素mRNA短暂性增加

铃声刺激诱发惊厥 ,原位杂交法检测遗传性听源性癫痫易感大鼠 (P77PMC)一次与多次惊厥发作对杏仁核内胆囊收缩素 (CCK)mRNA含量的影响。结果发现 :( 1)惊厥未发作组大鼠杏仁核单位面积内的CCKmRNA阳性神经元数 (No/ 0 0 1mm2 )较少 ,为 8± 1;( 2 )惊厥发作一次组大鼠杏仁核单位面积内CCKmRNA阳性神经元数显著增加 ,发作后 30min时达到峰值 ,为 5 8± 5 (P <0 0 1) ,但是 2h后迅速降为正常 ,为 9± 2 (P >0 0 5 ) ;( 3)惊厥多次发作组大鼠在惊厥发作后 30min时 ,CCKmRNA阳性神经元数亦显著增加 ,为 2 2± 3 (P <0 0 1) ,但明显低于惊厥发作一次组大鼠 (P <0 0 1) ,1h即恢复正常 ,为 9± 3 (P >0 0 5 )。结果表明 ,惊厥发作后P77PMC大鼠杏仁核内CCKmR NA含量呈现迅速而短暂增加的特点 ,表明CCKmRNA参与惊厥的急性发作过程 ,提示CCKmRNA在惊厥发作早期阶段发挥了重要的抗惊厥作用     

海仁酸致痫大鼠海马组织AMPA受体GluR2表达的变化

目的　为了研究AMPA受体在癫痫发生中的作用。方法　本研究用免疫组织化学方法观察了海仁酸致痫大鼠海马组织AMPA GluR2受体的表达变化。结果　在侧脑室注射海仁酸后 1h ,4h ,12h ,2 4h及 7d ,大鼠海马CA3区及齿状回GluR2的表达明显减弱 ,显微图像分析 :与对照组相比 ,KA 4h ,KA 12h ,KA 2 4h ,KA 7d组大鼠海马组织GluR2阳性神经元平均光密度值降低 ,差异有显著性 (P <0 0 5 )。结论　在癫痫发作过程中AMPA受体 GluR2亚单位表达改变可能与癫痫发作导致的神经元损伤有密切关系。     

海马胆囊收缩素对大鼠癫痫发作的影响及其机制

目的和方法：采用原位杂交技术,观察遗传性听源性癫痫易感大鼠海马内ＣＣＫｍＲＮＡ表达的改变及少我注射ＣＣＫ３及其受体阻断剂对大鼠癫痫发作的影响。结果：（１）癫痫发作大鼠海马内ＣＣＫｍＲＮＡ表达明显增强（Ｐ〈０．０５－０．０１）,但癫痫反复发作的大嫌海马内ＣＣＫｍＲＮＡ表达的较癫痫发作一次大鼠明显减少（Ｐ〈０．０５）,海马ＣＡ主射Ｌ３６５后,ＣＣＫ８压抑癫痫发作的作用消失（Ｐ〈０．０１）。结论：ＣＣＫ     

遗传性癫痫易感大鼠脑内NMDAR1基因表达

N-甲基-D天门冬氨酸(NMDA)受体与癫痫及癫痫易感性的形成密切相关. 以遗传性癫痫易感大鼠P77PMC为研究对象, 通过RNA印迹杂交检测,NMDA受体一型亚单位(NMDAR1)mRNA在惊厥后不同脑区表达, 结果显示: P77PMC大鼠惊厥后, 大脑皮层、海马、皮层下、下丘NMDAR1 mRNA表达呈时间依赖性增加;比较惊厥即刻与惊厥后24 h, 四个脑区NMDAR1 mRNA分别增加了111%、113%、165%和202%. 提示NMDA受体 亚单位受惊厥活动调控,并参与惊厥的发生、发展及惊厥后突触结构的重建.     

依托咪酯对大鼠杏仁核点燃模型的抑制作用

目的:研究依托咪(Etomidate,ET)对大鼠杏仁核点燃发作的抑制及其抗癫痫作用.方法:测定ET对大鼠杏仁核点燃发作的脑电活动及行为变化指标的影响,测定ET对GABAA受体拮抗剂印防己毒素诱发小鼠惊厥的影响.结果:依托咪酯(6～9mg·kg-1)可抑制杏仁核点燃发作,缩短后放电时程,降低Racine's分级(P＜0.01);ET对GABAA受体拮抗剂印防己毒素致惊小鼠有抑制作用.结论:依托咪酯对大鼠杏仁核点燃模型和印防己毒素致惊小鼠均具有抑制作用,可能与GABA神经系统抑制作用有关.     

IL-1β、IL-lra对戊四氮致痫大鼠行为及皮层、海马脑电的影响

目的:了解白细胞介素1β(IL-1β)在癫痫发作中的作用.方法:采用记录脑电图(EEG)同时观察行为的方法,观察IL-1β和IL-1受体拮抗剂(IL-1ra) 侧脑室注射对戊四氮(PTZ)致痫大鼠行为和皮层、海马EEG的影响.结果:IL -1β能明显缩短 PTZ致大鼠急性惊厥发作及痫波发放的潜伏期,增加痫波的发放频率.IL -1ra能减少急性惊厥痫波发放频率,对急性惊厥发作及痫波发放的潜伏期和惊厥发作强度无明显影响.但IL-1ra能显著延长大鼠点燃后PTZ诱导的惊厥发作和痫波发放的潜伏期,减轻惊厥发作强度.结论:内源性IL-1β是促进癫痫发作的因素之一,可能在癫痫慢性发展中提高大脑神经元的兴奋性中起着重要作用.     

听源性遗传癫痫易感大鼠大脑皮层胆囊收缩素mRNA的原位杂交检测

本实验用原位杂交法,对听源性遗传癫痫易感大鼠（P77PMC)癫痫发作前,单次癫痫发作和多次发作时大脑颞皮层CCK mRNA阳性信号进行了检测,结果显示：（1）单次和多次癫痫发作后颞皮层CCK mRNA阳性神经元数量明显增加（P＜0．01）;（2）多次癫痫发作者上述脑区CCK mRNA阳性神经元数量较单次癫痫发作有明显的下降（P＜0．01）,大脑颞皮层CCK mRNA增高表明,CCK mRNA在癫痫发作过程中起了某种作用,多次癫痫发作大鼠CCK mRNA表达降低提示,单次和多次癫痫发作时大脑皮层CCK mRNAl转录的调控可能存在不同的机制。     

氯胺酮、丙咪嗪以及两者联合用药对Wistar Kyoto大鼠抑郁样行为的作用北大核心CSCD

本文旨在研究氯胺酮、丙咪嗪或两者联合用药对Wistar Kyoto(WKY)大鼠抑郁样行为的治疗效果和机制。取6周龄Wistar大鼠作为正常对照,给同龄WKY大鼠(抑郁症模型)腹腔注氯胺酮(给药1周,停药1周)、丙咪嗪(给药2周)或氯胺酮联合丙咪嗪。行糖水偏好及强迫游泳实验观察各组大鼠抑郁样行为的变化,用Western blot检测大鼠缰核β钙/钙调素依赖蛋白激酶II(βform of calcium/calmodulin-dependent protein kinase type II,βCa MKII)和膜谷氨酸受体1(glutamate receptor 1,Glu R1)蛋白表达,以及前额叶皮质的膜Glu R1蛋白表达。结果显示,与Wistar大鼠相比,WKY大鼠糖水偏好程度显著降低,强迫游泳实验中不动时间显著增加;单独氯胺酮治疗对WKY大鼠的抑郁样行为没有显著作用,而丙咪嗪或氯胺酮联合丙咪嗪治疗可显著减少WKY大鼠不动时间。与Wistar大鼠相比,WKY大鼠缰核βCa MKII和膜Glu R1蛋白表达显著上调,前额叶皮质的膜Glu R1蛋白表达显著下调;单独氯胺酮治疗对WKY大鼠缰核βCa MKII和膜Glu R1蛋白表达没有显著作用,但可上调前额叶皮质的膜GluR1蛋白表达;丙咪嗪或氯胺酮联合丙咪嗪治疗均可显著下调WKY大鼠缰核βCa MKII和膜Glu R1蛋白表达,上调前额叶皮质的膜Glu R1蛋白表达,丙咪嗪对上述蛋白表达的作用和联合用药之间无显著差异。以上结果提示,丙咪嗪治疗2周显著改善了WKY大鼠的抑郁样行为,联合使用氯胺酮不能增强丙咪嗪的疗效;丙咪嗪的抗抑郁机制可能与缰核中βCa MKII及膜Glu R1表达下调以及前额叶皮质的膜GluR1表达上调有关。     

氯胺酮、丙咪嗪以及两者联合用药对Wistar Kyoto大鼠抑郁样行为的作用

本文旨在研究氯胺酮、丙咪嗪或两者联合用药对Wistar Kyoto(WKY)大鼠抑郁样行为的治疗效果和机制。取6周龄Wistar大鼠作为正常对照,给同龄WKY大鼠(抑郁症模型)腹腔注氯胺酮(给药1周,停药1周)、丙咪嗪(给药2周)或氯胺酮联合丙咪嗪。行糖水偏好及强迫游泳实验观察各组大鼠抑郁样行为的变化,用Western blot检测大鼠缰核β钙/钙调素依赖蛋白激酶II(βform of calcium/calmodulin-dependent protein kinase type II,βCa MKII)和膜谷氨酸受体1(glutamate receptor 1,Glu R1)蛋白表达,以及前额叶皮质的膜Glu R1蛋白表达。结果显示,与Wistar大鼠相比,WKY大鼠糖水偏好程度显著降低,强迫游泳实验中不动时间显著增加;单独氯胺酮治疗对WKY大鼠的抑郁样行为没有显著作用,而丙咪嗪或氯胺酮联合丙咪嗪治疗可显著减少WKY大鼠不动时间。与Wistar大鼠相比,WKY大鼠缰核βCa MKII和膜Glu R1蛋白表达显著上调,前额叶皮质的膜Glu R1蛋白表达显著下调;单独氯胺酮治疗对WKY大鼠缰核βCa MKII和膜Glu R1蛋白表达没有显著作用,但可上调前额叶皮质的膜GluR1蛋白表达;丙咪嗪或氯胺酮联合丙咪嗪治疗均可显著下调WKY大鼠缰核βCa MKII和膜Glu R1蛋白表达,上调前额叶皮质的膜Glu R1蛋白表达,丙咪嗪对上述蛋白表达的作用和联合用药之间无显著差异。以上结果提示,丙咪嗪治疗2周显著改善了WKY大鼠的抑郁样行为,联合使用氯胺酮不能增强丙咪嗪的疗效;丙咪嗪的抗抑郁机制可能与缰核中βCa MKII及膜Glu R1表达下调以及前额叶皮质的膜GluR1表达上调有关。     

ADAR2-dependent RNA editing of AMPA receptor subunit GluR2 determines vulnerability of neurons in forebrain ischemia

ADAR2 is a nuclear enzyme essential for GluR2 pre-mRNA editing at Q/R site-607, which gates Ca2+ entry through AMPA receptor channels. Here, we show that forebrain ischemia in adult rats selectively reduces expression of ADAR2 enzyme and, hence, disrupts RNA Q/R site editing of GluR2 subunit in vulnerable neurons. Recovery of GluR2 Q/R site editing by expression of exogenous ADAR2b gene or a constitutively active CREB, VP16-CREB, which induces expression of endogenous ADAR2, protects vulnerable neurons in the rat hippocampus from forebrain ischemic insult. Generation of a stable ADAR2 gene silencing by delivering small interfering RNA (siRNA) inhibits GluR2 Q/R site editing, leading to degeneration of ischemia-insensitive neurons. Direct introduction of the Q/R site edited GluR2 gene, GluR2(R607), rescues ADAR2 degeneration. Thus, ADAR2-dependent GluR2 Q/R site editing determines vulnerability of neurons in the rat hippocampus to forebrain ischemia.     

The role of RNA editing of kainate receptors in synaptic plasticity and seizures

The ionotropic glutamate receptor subunit GluR6 undergoes developmentally and regionally regulated Q/R site RNA editing that reduces the calcium permeability of GluR6-containing kainate receptors. To investigate the functional significance of this editing in vivo, we engineered mice deficient in GluR6 Q/R site editing. In these mutant mice but not in wild types, NMDA receptor-independent long-term potentiation (LTP) could be induced at the medial perforant path-dentate gyrus synapse. This indicates that kainate receptors with unedited GluR6 subunits can mediate LTP. Behavioral analyses revealed no differences from wild types, but mutant mice were more vulnerable to kainate-induced seizures. Together, these results suggest that GluR6 Q/R site RNA editing may modulate synaptic plasticity and seizure vulnerability.     

Dramatic Increase of the RNA Editing for Glutamate Receptor Subunits During Terminal Differentiation of Clonal Human Neurons

Abstract: RNA editing plays an important role in determining physiological characteristics of certain glutamate-gated receptor (GluR) channels such as Ca²⁺ permeability and desensitization kinetics. In one case, the editing changes a gene-encoded glutamine (Q) to an arginine (R) codon located in the channel-forming domain of the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptor subunit GluR-B and also the kainate receptor subunits GluR5 and GluR6. Another case of RNA editing alters an arginine (R) to a glycine (G) codon at a position termed the "R/G" site of AMPA subunits GluR-B, C, and D. Double-stranded RNA-specific adenosine deaminases (DRADA) have been implicated as agents involved in the editing. By using a human teratocarcinoma cell line, NT2, we investigated the change of the RNA editing of GluR subunits in conjunction with the expression of two DRADA members, DRADA1 and DRADA2 genes, during neuronal differentiation. Whereas Q/R and R/G site RNA editing both become progressively activated in differentiating NT2 cells, the expression of the two DRADA genes can already be detected even in the undifferentiated NT2 cells. Development of the editing machinery appears to require, in addition to DRADA enzymes, a currently unidentified mechanism(s) that may become activated during neuronal differentiation.     

Developmentally regulated, combinatorial RNA processing modulates AMPA receptor biogenesis

The subunit composition determines AMPA receptor (AMPA-R) function and trafficking. Mechanisms underlying channel assembly are thus central to the efficacy and plasticity of glutamatergic synapses. We previously showed that RNA editing at the Q/R site of the GluR2 subunit contributes to the assembly of AMPA-R heteromers by attenuating formation of GluR2 homotetramers. Here we report that this function of the Q/R site depends on subunit contacts between adjacent ligand binding domains (LBDs). Changes of LBD interface contacts alter GluR2 assembly properties, forward traffic, and expression at synapses. Interestingly, developmentally regulated RNA editing within the LBD (at the R/G site) produces analogous effects. Our data reveal that editing to glycine reduces the self-assembly competence of this critical subunit and slows GluR2 maturation in the endoplasmic reticulum (ER). Therefore, RNA editing sites, located at strategic subunit interfaces, shape AMPA-R assembly and trafficking in a developmentally regulated manner.     

Amino acid substitutions in the pore helix of GluR6 control inhibition by membrane fatty acids

RNA editing at the Q/R site in the GluR5 and GluR6 subunits of neuronal kainate receptors regulates channel inhibition by lipid-derived modulators including the cis-unsaturated fatty acids arachidonic acid and docosahexaenoic acid. Kainate receptor channels in which all of the subunits are in the edited (R) form exhibit strong inhibition by these compounds, whereas wild-type receptors that include a glutamine (Q) at the Q/R site in one or more subunits are resistant to inhibition. In the present study, we have performed an arginine scan of residues in the pore loop of the GluR6(Q) subunit. Amino acids within the range from -19 to +7 of the Q/R site of GluR6(Q) were individually mutated to arginine and the mutant cDNAs were expressed as homomeric channels in HEK 293 cells. All but one of the single arginine substitution mutants yielded functional channels. Only weak inhibition, typical of wild-type GluR6(Q) channels, was observed for substitutions +1 to +6 downstream of the Q/R site. However, arginine substitution at several locations upstream of the Q/R site resulted in homomeric channels exhibiting strong inhibition by fatty acids, which is characteristic of homomeric GluR6(R) channels. Based on homology with the pore loop of potassium channels, locations at which R substitution induces susceptibility to fatty acid inhibition face away from the cytoplasm toward the M1 and M3 helices and surrounding lipids.     

Dimerization of ADAR2 is mediated by the double-stranded RNA binding domain

Members of the family of adenosine deaminases acting on RNA (ADARs) can catalyze the hydrolytic deamination of adenosine to inosine and thereby change the sequence of specific mRNAs with highly double-stranded structures. The ADARs all contain one or more repeats of the double-stranded RNA binding motif (DRBM). By both in vitro and in vivo assays, we show that the DRBMs of rat ADAR2 are necessary and sufficient for dimerization of the enzyme. Bioluminescence resonance energy transfer (BRET) demonstrates that ADAR2 also exists as dimers in living mammalian cells and that mutation of DRBM1 lowers the dimerization affinity while mutation of DRBM2 does not. Nonetheless, the editing efficiency of the GluR2 Q/R site depends on a functional DRBM2. The ADAR2 DRBMs thus serve differential roles in RNA dimerization and GluR2 Q/R editing, and we propose a model for RNA editing that incorporates the new findings.     

Editing of AMPA and Serotonin 2C Receptors in Individual Central Neurons,Controlling Wakefulness

(1) Pre-mRNA editing of serotonin 2C (5-HT_2C) and glutamate (Glu) receptors (R) influences higher brain functions and pathological states such as epilepsy, amyotrophic lateral sclerosis, and depression. Adenosine deaminases acting on RNA (ADAR1–3) convert adenosine to inosine on synthetic RNAs, analogous to 5-HT_2cR and GluR. The order of editing as well as mechanisms controlling editing in native neurons is unknown. (2) With single-cell RT-PCR we investigated the co-expression of ADAR genes with GluR and 5-HT_2CR and determined the editing status at known sites in the hypothalamic tuberomamillary nucleus, a major center for wakefulness and arousal. (3) The most frequently expressed enzymes were ADAR1, followed by ADAR2. The Q/R site of GluR2 was always fully edited. Editing at the R/G site in the GluR2 (but not GluR4) subunit was co-ordinated with ADAR expression: maximal editing was found in neurons expressing both ADAR2 splice variants of the deaminase domain and lacking ADAR3. (4) Editing of the 5-HT_2CR did not correlate with ADAR expression. The 5-HT_2CR mRNA was always edited at A, in the majority of cells at B sites and variably edited at E, C and D sites. A negative correlation was found between editing of C and D sites. The GluR4 R/G site editing was homogeneous within individuals: it was fully edited in all neurons obtained from 12 rats and under-edited in six neurons obtained from three rats. (5) We conclude that GluR2 R/G editing is controlled at the level of ADAR2 and therefore this enzyme may be a target for pharmacotherapy. On the other hand, further factors/enzymes besides ADAR must control or influence 5-HT_2CR and GluR pre-mRNA editing in native neurons; our data indicate that these factors vary between individuals and could be predictors of psychiatric disease.     

AMPA receptor tetramerization is mediated by Q/R editing

AMPA-type glutamate receptors (AMPARs) play a major role in excitatory synaptic transmission and plasticity. Channel properties are largely dictated by their composition of the four subunits, GluR1-4 (or A-D). Here we show that AMPAR assembly and subunit stoichiometry are determined by RNA editing in the pore loop. We demonstrate that editing at the GluR2 Q/R site regulates AMPAR assembly at the step of tetramerization. Specifically, edited R subunits are largely unassembled and ER retained, whereas unedited Q subunits readily tetramerize and traffic to synapses. This assembly mechanism restricts the number of the functionally critical R subunits in AMPAR tetramers. Therefore, a single amino acid residue affects channel composition and, in turn, controls ion conduction through the majority of AMPARs in the brain.