补肾活血复方对成骨细胞谷氨酸NMDA(N-methyl-D-aspartate)受体信号通路的影响

目的:观察补肾活血复方含药血清OB增殖、ALP活性、NR1、NR2a、NR2d蛋白表达的影响。方法:(1)取1d龄、5d龄SD大鼠OB、OC,建立OB-OC共育体系;(2)MTT法检测OB增殖;ALP检测试剂盒检测ALP活性;Western-blot检测NR1、NAR2a、NR2d蛋白含量的情况。结果:补肾活血复方血清可增强OB增殖、提高ALP活性、促使OB NR1、NR2a、NR2d蛋白的含量增加。加入MK801降低OB增殖、ALP活性、OB NR1、NR2a、NR2d蛋白的含量。结论:补肾活血复方含药血清可通过谷氨酸NR信号通路促进OB的骨形成作用。

氟中毒大鼠脑组织中NMDA受体及内质网应激相关通路蛋白的表达

背景:前期研究发现N-甲基-D-天冬氨酸(N-methyl-D-aspartic acid receptor,NMDA)受体与氟相关,但其在氟诱导的内质网应激中的作用尚不明确。目的:观察实验性氟中毒大鼠脑组织中兴奋性神经递质NMDA受体及内质网应激IRE1α-ASK1-JNK通路蛋白表达变化,并应用NMDA受体抑制剂干预SH-SY5Y细胞,探讨氟中毒神经系统损伤的发病机制。方法:(1)动物模型:18只1月龄SD大鼠随机分为对照组(饮水含氟量<0.5 mg/L)、低氟组(饮水含氟量为10.0 mg/L)、高氟组(饮水含氟量为100.0 mg/L),每组6只,雌雄各半。饮水摄氟饲养6个月后,观察大鼠氟斑牙发生情况,测定24 h尿氟含量;大鼠麻醉处死后取脑组织观察组织病理变化,蛋白印迹法检测脑组织中NMDA受体及IRE1α、ASK1、JNK蛋白表达。(2)细胞模型:体外培养SH-SY5Y细胞,选择终浓度为0.3 mmol/L和3 mmol/L的氟化钠染氟处理,并用10μmol/L的NMDA受体拮抗剂Ifenprodil、MK-801对染氟细胞进行干预,观察相关蛋白改变。结果与结论:(1)高氟组大鼠氟斑牙发生率、尿氟水平显著高于对照组和低氟组(P<0.05);(2)与对照组相比,低氟组大鼠海马CA3区神经细胞胞质嗜碱性略增加,高氟组CA3区神经细胞排列紊乱,嗜碱性增加,部分细胞核固缩;(3)大鼠脑组织内,高氟组NR2A与低氟组NR2B的蛋白表达明显高于对照组(P<0.05),且高氟组NR2B、IRE1、ASK1、p-JNK蛋白表达明显高于对照组和低氟组(P<0.05);(4)SH-SY5Y细胞内,高氟组NR1、NR2A、NR2B蛋白表达明显高于对照组(P<0.05),且高氟+Ifenprodil组、高氟+MK-801组NR1、NR2A蛋白表达均明显低于高氟组(P<0.05),高氟+Ifenprodil组NR2B蛋白表达也明显低于高氟组(P<0.05);(5)SH-SY5Y细胞内,高氟组IRE1、ASK1、p-JNK蛋白表达明显高于对照组(P<0.05),且高氟+Ifenprodil组、高氟+MK-801组ASK1、p-JNK蛋白表达均明显低于高氟组(P<0.05),高氟+Ifenprodil组IRE1蛋白水平也明显低于高氟组(P<0.05);(6)提示:过量氟摄入可激活中枢神经系统NMDA受体,引起内质网应激IRE1α、ASK1、p-JNK蛋白表达增加,使用NMDA受体抑制剂对氟中毒所致内质网应激具有一定缓解作用。

In silico insight into Amurensinine - an N-Methyl-D-Aspartate receptor antagonist

BACKGROUND Some isopavines can exhibit important biological activity in the treatment of neurological disorders since it is considered an antagonist of the specific Nmethyl-D-Aspartate(NMDA)receptor.Amurensinine is an isopavine which still has few studies.In view of the potential of isopavines as NMDA receptor antagonists,theoretical studies using bioinformatics were carried out in order to investigate whether Amurensinine binds to the NMDA receptor and to analyze the receptor/Ligand complex.This data can contribute to understanding of the onset of neurological diseases and contribute to the planning of drugs for the treatment of neurological diseases involving the NMDA receptor.AIM To investigate the interaction of the antagonist Amurensinine on the GluN1A/GluN2B isoform of the NMDA receptor using bioinformatics.METHODS The three-dimen-sional structure of the GluN1A/GluN2B NMDA receptor was selected from the Protein Data Bank(PDB)-PDB:4PE5,and the three-dimensional structure of Amurensinine(ligand)was designed and optimized using ACD/SchemsketchTM software.Prediction of the protonation state of Amurensinine at physiological pH was performed using MarvinSketch software(ChemAxon).Protonated and non-protonated Amurensin were prepared using AutoDock Tools 4 software and simulations were performed using Autodock Vina v.1.2.0.The receptor/Ligand complexes were analyzed using PyMol(Schrödinger,Inc)and BIOVIA Discovery Studio(Dassault Systemes)software.To evaluate the NMDA receptor/Amurensinine complex and validate the molecular docking,simulations using NMDA receptor and Ifenprodil antagonist were performed under the same conditions.Ifenprodil was also designed,optimized and protonated,under the same conditions as Amurensinine.RESULTS Molecular docking simulations showed that both non-protonated and protonated Amurensinine bind to the amino terminal domain(ATD)domain of the GluN1A/GluN2B NMDA receptor with significant affinity energy,-7.9 Kcal/mol and-8.1 Kcal/mol,respectively.The NMDA receptor/non-protonated Amurensinine complex was stabilized by 15 bonds,while the NMDA receptor/protonated Amurensinine complex was stabilized by less than half,6 bonds.Despite the difference in the number of bonds,the variation in bond length and the average bond length values are similar in both complexes.The complex formed by the NMDA receptor and Ifenprodil showed an affinity energy of-8.2 Kcal/mol,a value very close to that obtained for the NMDA receptor/Amurensinine complex.Molecular docking between Ifenprodil and the GluN1A/GluN2B NMDA receptor demonstrated that this antagonist interacts with the ATD of the receptor,which validates the simulations performed with Amurensinine.CONCLUSION Amurensinine binds to the NMDA receptor on ATD,similar to Ifenprodil,and the affinity energy is closer.These data suggest that Amurensinine could behave as a receptor inhibitor,indicating that this compound may have a potential biological application,which should be evaluated by in vitro and preclinical assays.

Anti N-Methyl-D-Aspartate (NMDA) Receptor Encephalitis with Frustrated Diagnosis Course: A Case Report

Anti-N-methyl-D-aspartate (NMDA) receptor encephalitis is a rare disease with uncertain etiology and pathogenesis that affects young women. Its diagnosis can be delayed because of the nonspecific neuropsychiatric symptoms in the foreground. This article describes the details of a recent complicated case of a patient with this condition which is related to an ovarian teratoma. Correct diagnostic and prompt treatment of anti-NMDA receptor encephalitis remains a serious clinical challenge due to its unspecific manifestations and varying response to treatments. The information will be of interest to clinicians working with encephalitis patients.

小儿抗NMDA受体脑炎的临床护理干预效果分析

此次对小儿抗NMDA受体脑炎的临床护理方面进行深度探究。方法 根据调研内容为依据,从科室进行病例的选入,参与调研对象各指标达标者为80例,均在入院后临床诊断确定病症,对此次患儿实施分组后展开护理工作(随机法),对照组40例主要给予优质护理服务,观察组在此基础上,评估患儿精神症状,增加心理护理干预,该组例数与对照组同步,在干预后对此次护理满意度方面进行综合评估,对出现并发症的患儿实施记录与组间对比,查看此次各小组患儿住院所用时间。结果 以指定的问卷表形式对患儿和家属开展满意度调查,回收份数100%,对比各小组满意度,其中观察组满意度更为突出;两组均有部分患儿在治疗期间发生并发症,经统计对照组出现例数居多;对比住院天数,对照组时间延长(P<0.05)。结论 此次主要针对NMDA受体脑炎患儿实施临床护理服务,经过研究表明优质护理服务配合心理护理能够帮助患儿更有效地改善症状,提升患儿和家属满意度。

N-methyl-D-aspartate glutamate receptors (NMDARs) in stroke pathogenesis and treatments

N-methyl-D-aspartate glutamate receptors(NMDARs)play crucial roles in the pathogenesis of neuronal injuries following a stroke insult;therefore,a plethora of preclinical studies focus on better understanding functions of NMDARs and their associated signaling pathways.Over the past decades,NMDARs have been found to exert dual effects in neuronal deaths signaling and neuronal survival signaling during cerebral ischemia.Moreover,many complex intracellular signaling pathways downstream of NMDAR activation have been elucidated,which provide novel targets for developing much-needed neuro-protectants for patients with stroke.In this review,we will discuss the recent progress in understanding the underlying mechanisms of stroke related to NMDAR activation and the potential therapeutic strategies based on these discoveries.

N-Methyl-D-Aspartate受体拮抗剂对脑缺血后成年大鼠神经干细胞内源性激活的实验研究

目的 研究N - Methyl- D- Aspartate(NMDA)受体拮抗剂MK- 80 1对脑缺血后神经干细胞(NSC)激活的作用。方法 将4 0只SD大鼠分成对照组和实验组,两组大鼠均采用传统线栓法作成大脑中动脉缺血再灌注模型,实验组大鼠腹腔注射MK- 80 1,对照组腹腔注射生理盐水,通过免疫组织化学技术标记鼠脑海马齿状回颗粒细胞层(SGZ)、室管膜下层(SVZ)及梗死皮质周边区注射后第3、7、11、18天的Brdu、Nestin阳性细胞数。结果 对照组大鼠Brdu、Nestin阳性细胞7d在SGZ出现一小高峰,然后迅速下降,11d阳性细胞甚少,梗死皮质周边区更少;而实验组Brdu、Nestin阳性细胞3d在SVZ明显表达,7～11d在SGZ区达高峰,并可持续至18d,同样梗死皮质区Brdu、Nestin阳性细胞7～18d表达明显,两组比较,有统计学意义(P<0 .0 1)。结论 NMDA受体拮抗剂MK- 80 1在脑缺血后,能促进NSC的增殖、分化。

Discovery of GluN2A subtype-selective N-methyl-d-aspartate(NMDA)receptor ligands

The N-methyl-d-aspartate(NMDA)receptors,which belong to the ionotropic Glutamate receptors,constitute a family of ligand-gated ion channels.Within the various subtypes of NMDA receptors,the GluN1/2A subtype plays a significant role in central nervous system(CNS)disorders.The present article aims to provide a comprehensive review of ligands targeting GluN2A-containing NMDA receptors,encompassing negative allosteric modulators(NAMs),positive allosteric modulators(PAMs)and competitive antagonists.Moreover,the ligands’structure–activity relationships(SARs)and the binding models of representative ligands are also discussed,providing valuable insights for the clinical rational design of effective drugs targeting CNS diseases.

N-methyl-D-aspartate receptor subunit 1 regulates neurogenesis in the hippocampal dentate gyrus of schizophrenia-like mice

N-methyl-D-aspartate receptor hypofunction is the basis of pathophysiology in schizophrenia. Blocking the N-methyl-D-aspartate receptor impairs learning and memory abilities and induces pathological changes in the brain. Previous studies have paid little attention to the role of the N-methyl-D-aspartate receptor subunit 1 (NR1) in neurogenesis in the hippocampus of schizophrenia. A mouse model of schizophrenia was established by intraperitoneal injection of 0.6 mg/kg MK-801, once a day, for 14 days. In N-methyl-D-aspartate-treated mice, N-methyl-D-aspartate was administered by intracerebroventricular injection in schizophrenia mice on day 15. The number of NR1-, Ki67- or BrdU-immunoreactive cells in the dentate gyrus was measured by immunofluorescence staining. Our data showed the number of NR1-immunoreactive cells increased along with the decreasing numbers of BrdU- and Ki67-immunoreactive cells in the schizophrenia groups compared with the control group. N-methyl-D-aspartate could reverse the above changes. These results indicated that NR1 can regulate neurogenesis in the hippocampal dentate gyrus of schizophrenia mice, supporting NR1 as a promising therapeutic target in the treatment of schizophrenia. This study was approved by the Experimental Animal Ethics Committee of the Ningxia Medical University, China (approval No. 2014-014) on March 6, 2014.

Influences of levodopa on expression of N-methyl-D-aspartate receptor-1-subunit in the visual cortex of monocular deprivation rats

AIM: Many studies have demonstrated N-methyl-D-aspartate receptor-1-subunit (NMDAR1) is associated with amblyopia. The effectiveness of levodopa in improving the visual function of the children with amblyopia has also been proved. But the mechanism is undefined. Our study was to explore the possible mechanism. METHODS: Sixty 14-day-old healthy SD rats were randomly divided into 4 groups, including normal group, monocular deprivation group, levodopa group and normal saline group, 15 rats each. We sutured all the rats' unilateral eyelids except normal group to establish the monocular deprivation animal model and raise them in normal sunlight till 45-day-old. NMDAR1 was detected in the visual cortex with immunohistochemistry methods, Western Blot and Real time PCR. LD and NS groups were gavaged with levodopa (40mg/kg) and normal saline for 28 days respectively. NMDAR1 was also detected with the methods above. RESULTS: NMDAR1 in the visual cortex of MD group was less than that of normal group. NMDAR1 in the visual cortex of LD group was more than that of NS group. CONCLUSION: NMDAR1 is associated with the plasticity of visual development. Levodopa may influence the expression of NMDAR1 and improve visual function, and its target may lie in the visual cortex.

Propofol effectively inhibits lithium-pilocarpine-induced status epilepticus in rats via downregulation of N-methyl-D-aspartate receptor 2B subunit expression

Status epilepticus was induced via intraperitoneal injection of lithium-pilocarpine.The inhibitory effects of propofol on status epilepticus in rats were judged based on observation of behavior,electroencephalography and 24-hour survival rate.Propofol（12.5-100 mg/kg） improved status epilepticus in a dose-dependent manner,and significantly reduced the number of deaths within 24 hours of lithium-pilocarpine injection.Western blot results showed that,24 hours after induction of status epilepticus,the levels of N-methyl-D-aspartate receptor 2A and 2B subunits were significantly increased in rat cerebral cortex and hippocampus.Propofol at 50 mg/kg significantly suppressed the increase in N-methyl-D-aspartate receptor 2B subunit levels,but not the increase in N-methyl-D-aspartate receptor 2A subunit levels.The results suggest that propofol can effectively inhibit status epilepticus induced by lithium-pilocarpine.This effect may be associated with downregulation of N-methyl-D-aspartate receptor 2B subunit expression after seizures.

急性症状性发作对抗NMDA受体脑炎患者预后的影响

目的探讨急性症状性发作(ASS)是否为抗N-甲基-D-天冬氨酸(NMDA)受体脑炎功能预后不良的危险因素。方法选择2013年2月至2020年8月在首都医科大学附属北京天坛医院神经内科就诊的68例抗NMDA受体脑炎患者进行研究。根据改良Rankin量表(mRS)将患者预后分为两组:预后良好组(mRS≤2)和预后不良组(mRS>2)。采用单因素和多因素Logistic回归分析评估ASS与抗NMDA受体脑炎功能预后的相关性。结果与预后良好组相比,预后不良组ASS(P=0.033)、精神行为异常(P=0.007)、脑脊液寡克隆区带阳性(P=0.032)比例均较高,男性(P=0.045)比例较低,年龄(P=0.010)较大,发病至首次免疫治疗时间(P=0.009)较长。多因素Logistic回归分析显示:经校正年龄、性别、发病至首次免疫治疗时间、精神行为异常、脑脊液寡克隆区带阳性后,ASS比例增加是抗NMDA受体脑炎患者预后不良的独立危险因素(OR=18.023,95%CI:1.594~203.771,P=0.019)。结论ASS是抗NMDA受体脑炎的主要表现,对免疫治疗疗效明确,也是脑炎功能预后不良的独立危险因素,临床工作中应注意该症状的早期诊断和治疗,对提高患者的预后有重要意义。

洛伐他汀调节NMDA受体功能减缓NMDA兴奋性毒性损害

目的:检测洛伐他汀(lovastatin,LOV)对N⁃甲基⁃D⁃天门冬氨酸(N⁃methyl⁃D⁃aspartate,NMDA)诱导的兴奋性毒性的神经保护作用并探讨LOV调节NMDA受体功能在神经保护中的潜在机制。方法:培养的大鼠原代神经元细胞分未处理组、LOV组、NMDA组、LOV+NMDA组、谷氨酸(glutamate,Glu)组及Glu+APV(一种特异性NMDA受体拮抗剂)组。免疫荧光染色检测神经元形态,TUNEL分析检测神经元凋亡,免疫印迹测定蛋白水平,生物素化法检测细胞表面受体。结果:①与NMDA组或Glu组少数幸存微管相关蛋白(microtubule⁃associated protein 2,MAP⁃2)阳性神经元相比,LOV+NMDA组和Glu+APV组MAP⁃2阳性神经元的数量明显增多,神经元树突的数目和长度均明显增加(P<0.001);②与NMDA组或Glu组TUNEL阳性细胞显著增多相比,LOV+NMDA组或Glu+APV组TUNEL阳性细胞显著减少(P<0.001);③与未处理组相比,NMDA组NMDA受体蛋白(N⁃methyl⁃D⁃aspartate receptor,NR2B)表达显著减少(P<0.001),而LOV预处理后增加NR2B蛋白表达(P<0.05);④生物素化法检测细胞表面受体显示,NMDA处理导致细胞表面大部分NR2B丢失(P<0.001),LOV预处理能显著减少NMDA诱导的细胞表面NR2B丢失(P<0.05)。进一步研究显示,NMDA处理后,NR2B在酪氨酸(tyrosine,Tyr)1472位点的磷酸化下降(P<0.05),LOV预处理显著恢复Tyr1472位点的磷酸化(P<0.05)。结论:LOV能减轻NMDA诱导的兴奋性毒性损害,这一作用可能与其影响NMDA受体亚单位NR2B的细胞内吞和/或胞内降解,进而调节NR2B表面分布有关。

Quantitative proteomic and phosphoproteomic analyses of the hippocampus reveal the involvement of NMDAR1 signaling in repetitive mild traumatic brain injury

The cumulative damage caused by repetitive mild traumatic brain injury can cause long-term neurodegeneration leading to cognitive impairment.This cognitive impairment is thought to result specifically from damage to the hippocampus.In this study,we detected cognitive impairment in mice 6 weeks after repetitive mild traumatic brain injury using the novel object recognition test and the Morris water maze test.Immunofluorescence staining showed that p-tau expression was increased in the hippocampus after repetitive mild traumatic brain injury.Golgi staining showed a significant decrease in the total density of neuronal dendritic spines in the hippocampus,as well as in the density of mature dendritic spines.To investigate the specific molecular mechanisms underlying cognitive impairment due to hippocampal damage,we performed proteomic and phosphoproteomic analyses of the hippocampus with and without repetitive mild traumatic brain injury.The differentially expressed proteins were mainly enriched in inflammation,immunity,and coagulation,suggesting that non-neuronal cells are involved in the pathological changes that occur in the hippocampus in the chronic stage after repetitive mild traumatic brain injury.In contrast,differentially expressed phosphorylated proteins were mainly enriched in pathways related to neuronal function and structure,which is more consistent with neurodegeneration.We identified N-methyl-D-aspartate receptor 1 as a hub molecule involved in the response to repetitive mild traumatic brain injury,and western blotting showed that,while N-methyl-D-aspartate receptor 1 expression was not altered in the hippocampus after repetitive mild traumatic brain injury,its phosphorylation level was significantly increased,which is consistent with the omics results.Administration of GRP78608,an N-methyl-D-aspartate receptor 1 antagonist,to the hippocampus markedly improved repetitive mild traumatic brain injury-induced cognitive impairment.In conclusion,our findings suggest that N-methyl-D-aspartate receptor 1 signaling in the hippocampus is involved in cognitive impairment in the chronic stage after repetitive mild traumatic brain injury and may be a potential target for intervention and treatment.

NMDA受体在偏头痛中作用的研究进展

N-甲基-D-天冬氨酸(N-methyl-D-aspartate,NMDA)受体是一种离子型谷氨酸受体,广泛表达于中枢神经系统,介导兴奋性突触传递的Ca2+内流,并在突触可塑性、学习、记忆等方面发挥重要作用。偏头痛是临床常见的原发性头痛,因其发作频繁,给患者带来严重的生活和心理负担。偏头痛的发病机制尚不明确,研究发现,谷氨酸及NMDA受体与偏头痛的发生关系密切。本文主要就NMDA受体与偏头痛的发生,NMDA受体拮抗剂与偏头痛的预防和治疗的相关进展进行综述,旨在为偏头痛的发病机制及药物治疗等提供参考。

p150glued缺失小鼠的脊髓运动神经元中NMDA受体增多

目的 探讨运动神经元病致病基因Dctn1编码蛋白p150glued对小鼠脊髓运动神经元中N-甲基-D-天冬氨酸(NMDA)受体的影响。方法 利用蛋白印迹法检测p150glued缺失(cKO)小鼠及对照(Ctrl)小鼠脊髓中NMDA受体亚基NR1和NR2B的含量。利用免疫荧光染色法观察Ctrl和cKO小鼠脊髓运动神经元中NRI分布的变化。结果 与Ctrl小鼠相比,6月龄cKO小鼠脊髓组织中NR1和NR2B的蛋白水平明显增加,cKO小鼠脊髓运动神经元中NR1阳性斑点数也明显增多、增大。结论 神经元中p150glued缺失可以引起6月龄小鼠脊髓运动神经元中NMDA受体亚基NR1和NR2B增多。

Changes in synaptic and extrasynaptic N-methyl-D-aspartate receptor-mediated currents at early-stage epileptogenesis in adult mice

Previous reports have shown that N-methyl-D-aspartate （NMDA） receptors are extensively involved in epilepsy genesis and recurrence. Recent studies have shown that synaptic and extrasynaptic NMDA receptors play different, or even opposing, roles in various signaling pathways, including synaptic plasticity and neuronal death. The present study analyzed changes in synaptic and extrasynaptic NMDA receptor-mediated currents during epilepsy onset. Mouse models of lithium chloride pilocarpLne-induced epilepsy were established, and hippocampal slices were prepared at 24 hours after the onset of status epilepticus. Synaptic and extrasynaptic NMDA receptor-mediated excitatory post-synaptic currents （NMDA-EPSCs） were recorded in CA1 pyramidal neurons by whole-cell patch clamp technique. Results demonstrated no significant difference in rise and delay time of synaptic NMDA-EPSCs compared with normal neurons. Peak amplitude, area-to-peak ratio, and rising time of extrasynaptic NMDA-EPSCs remained unchanged, but decay of extrasynaptic NMDA-EPSCs was faster than that of normal neurons, These results suggest that extrasynaptic NMDA receptors play a role in epileptogenesis.

基于NMDA-NO通路探讨亚麻醉剂量氯胺酮对术后认知功能障碍大鼠的影响及作用机制

目的探讨亚麻醉剂量氯胺酮调控N-甲基-D-天冬氨酸(NMDA)-一氧化氮(NO)通路对术后认知功能障碍大鼠的影响及作用机制。方法选取30只健壮的SD大鼠,将其随机分为空白组、手术组、手术+麻醉组,每组10只。手术+麻醉组采用结扎双侧颈总动脉致其重度狭窄的方法建立模型并腹腔注射腔注射盐酸氯胺酮麻醉,手术组只分离双侧颈总动脉不结扎,空白组不做处理。对大鼠行水迷宫实验;测定各组组织一氧化氮合酶(NOS)活力、肿瘤坏死因子(TNF)-α、白细胞介素(IL)-6、中枢特异性蛋白(S-100β)蛋白水平,NMDA受体(NMDAR)2B蛋白阳性表达,NMDA受体蛋白表达。结果手术组潜伏时间在术后第1、3天显著增加,象限百分比在术后第1、3天明显下降(P<0.05);与空白组和手术+麻醉组比较,手术组NOS活力、TNF-α、IL-6、S-100β蛋白水平、NMDAR2B蛋白阳性表达率和判定评分、受体蛋白表达水平均显著较高(P<0.05)。结论亚麻醉剂量氯胺酮可以调控NMDA-NO通路阻滞大鼠发生术后认知功能障碍。

Dose-dependent and combined effects of N-methyl-D-aspartate receptor antagonist MK-801 and nitric oxide synthase inhibitor nitro-L-arginine on the survival of retinal ganglion cells in adult hamsters

This study investigated the effects of daily intraperitoneal injections of N-methyl-D-aspartate receptor antagonist MK-801 and nitric oxide synthase inhibitor nitro-L-arginine （L-NA） on the survival of retinal ganglion cells （RGCs） at 1 and 2 weeks after unilateral optic nerve transection in adult hamsters. The left optic nerves of all animals were transected intraorbitally 1 mm from the optic disc and RGCs were retrogradely labeled with Fluorogold before they received different daily dosages of single MK-801 or L-NA as well as daily combinational treatments of these two chemicals. All experimental and control animals survived for 1 or 2 weeks after optic nerve transection. Our results revealed that the mean numbers of surviving RGCs increased and then decreased when the dosage of MK-801 （1.0, 3.0 and 4.5 mg/kg） and L-NA （1.5, 3.0, 4.5 and 6.0 mg/kg） increased at both 1 and 2 weeks survival time points. Daily combinational use of 1.0 mg/kg MK-801 and 1.5 mg/kg L-NA lead to a highest RGC number that was even higher than the sum of the RGC numbers in 1.0 mg/kg MK-801 and 1.5 mg/kg L-NA subgroups at 2 weeks. These findings indicated that both MK-801 and L-NA can protect axotomized RGCs in a dose-dependent manner and combinational treatment of these chemicals possesses a potentiative and protective effect.

N-methyl-D-aspartate receptor subtype 3A promotes apoptosis in developing mouse brain exposed to hyperoxia

In the present study, 7 day postnatal C57/BL6 wild-type mice （hyperoxia group） and 7 day postnatal N-methyI-D-aspartate receptor subtype 3A knockout mice （NR3A KO group） were exposed to 75% oxygen and 15% nitrogen in a closed container for 5 days. Wild-type mice raised in normoxia served as controls. TdT-mediated dUTP nick end labeling （TUNEL）/neuron-specific nuclear protein （NeuN） and 5-bromo-2＇-deoxyuridine （BrdU）/NeuN immunofluorescence staining showed that the number of apoptotic cells and the number of proliferative cells in the dentate subgranular zone significantly increased in the hyperoxia group compared with the control group. However, in the same hyperoxia environment, the number of apoptotic cells and the number of proliferative cells significantly decreased in the NR3A KO group compared with hyperoxia group. TUNEL＋/NeuN＋ and BrdU＋/NeuN~ cells were observed in the NR3A KO and the hyperoxia groups. These results demonstrated that the NR3A gene can promote cell apoptosis and mediate the potential damage in the developing brain induced by exposure to non-physiologically high concentrations of oxygen.