大鼠皮质N-甲基-D-天冬氨酸受体在脑损伤后的时相变化

目的；观测Ｎ－甲基－Ｄ－天冬氨酸（ＮＭＤＡ）受体在脑损伤后的变化规律以及与继发性脑水肿发生和发展的关系。方法：用放射性配基结合分析法对伤后不同时间的大鼠伤侧大脑皮质ＮＭＤＡ受体活性进行测定干湿法测伤后伤测皮质水含量。     

N-甲基-D-天冬氨酸受体-3亚基研究进展

<正>NMDA受体(N-methyl-D-aspartate receptor,NMDAR)是一种离子通道型谷氨酸受体,这类受体还包括KA受体(kainic acid receptor,KAR)和AMPA受体(α-amino-3-hydrox-y-5-methyl-4-isoxa-zolep-propionate receptor,AMPAR)。绝大部分NMDA受体分布于中枢神经系统,参与兴奋性突触传     

N-甲基-D-天冬氨酸受体在大鼠丘脑前核和扣带后回的表达

目的探讨大鼠丘脑前核和扣带后回内N-甲基-D-天冬氨酸受体NMDAR2A,NMDAR2B及NMDAR1(NR2A.NR2B及NR1)mRNA的表达,从形态学角度为系统研究丘脑前核的功能提供了依据。方法应用原位杂交方法检测丘脑前核及扣带后回内NR2A,NR2B以及NR1 mRNA的表达。结果原位杂交阳性反应产物为棕黄色,主要分布在神经元核周围胞浆中,胞核基本不着色。在丘脑前核,阳性神经元分布较密集,细胞形态较一致。扣带后回皮质阳性神经元在在大脑皮质不同部位分布有差异,分子层染色最弱,外颗粒层密集分布且染色增强,余四层较外颗粒层松散,染色细胞减少。结论 NR2A,NR2B以及NR1广泛分布在丘脑前核和扣带后回。     

糖尿病大鼠视网膜N-甲基-D-天门冬氨酸受体表达的变化

目的:观察糖尿病不同时期视网膜 N-甲基-D-天门冬氨酸(NMDA)受体各亚基的表达.方法:采用雄性 SD 大鼠腹腔内注射链脲佐菌素建立糖尿病大鼠模型,分别于4、8、12周灌注,取眼球、冷冻切片;免疫组织化学、原位杂交方法检测NMDA 受体 NRl、NR2A、NR2B 亚基表达的变化;用 RS IMAGE 软件进行图像分析.结果:NRl、NR2A、NR2B 基因及其蛋白表达在糖尿病第 4 周时开始升高,至12周升高具有统计学意义,特别是 NRl 的变化更为显著.结论:NMDA 受体各亚基的高表达参与了糖尿病视网膜病变.     

小鼠大脑皮质N-甲基-D-天冬氨酸(NMDA)受体的检定及其在衰老时的变化

以放射性配基结合分析法对正常成年小鼠(3月龄)大脑皮质NMDA受体作了检定,观察了衰老过程中小鼠NMDA受体、长时程电位增强(long-term potentiation,LTP)等的变化以及补肾中药复方对这些变化的影响。结果归纳如下:正常成年小鼠大脑皮质NMDA受体的最大结合容量(B_(max))和平衡解离常数(Kd)分     

低氧对脑N-甲基-D-天冬氨酸受体亚基2B的表达影响

<正>N-甲基-D-天冬氨酸(N-methyl-D-aspartate,NMDA)受体广泛存在于神经细胞的突触后膜上,有较高的钙离子通透性,是与学习记忆及精神性疾病密切相关的一类谷氨酸门控离子通道受体。该受体是由7种类型的亚基NR1,NR2A-D,NR3A、B组成的四聚体或五聚体,其中NR1与NR2、NR3之间不具有明显的同源关系。NMDAR亚基在突触形成和活性反应中发挥不同的调节作用,NR1/NR2A在成年大鼠神经系统突触可塑性     

N-甲基-D-天冬氨酸受体NR1亚基调控大脑皮层神经元放射状迁移

目的探讨N-甲基-D-天冬氨酸(NMDA)受体在大脑皮层发育过程中参与调控皮层神经元放射状迁移的情况。方法通过在体子宫内胚胎电转基因和RNA干扰技术(RNAi),在发育的大鼠胚胎脑内干扰NMDA受体的NR1亚基表达,结合荧光免疫组织化学技术,追踪基因转染上的神经元在大脑发育过程中的迁移途径和特征。结果转染上对照质粒的皮层神经元能通过放射状迁移,在出生后第7天(P7)之前迁移到皮层的正确位置,即2～3层,而干扰NR1基因表达后的神经元则不能正常地放射状迁移至皮层的2～3层,P7时仍停留在皮层深层位置,甚至发生区。结论 NMDA受体在大脑皮层神经元放射状迁移过程中起关键性作用,有助于理解胚胎发育过程中迁移的机制并为预防控制神经元迁移异常提供依据。     

N-甲基-D-天冬氨酸型受体亚单位-1在大鼠第三脑室室管膜细胞上的表达

目的　研究 N-甲基 - D-天冬氨酸型受体亚单位 - 1(NMDAR1)在大鼠第三脑室室管膜细胞上的表达。　方法　免疫组织化学技术。　结果　 (1) NMDAR1在第三脑室室管膜细胞中的表达呈强阳性 ;(2 ) NMDAR1阳性室管膜细胞的形态与分布 ,在雌、雄大鼠间不存在明显的性别差异。　结论　为脑脊液中的谷氨酸可通过 NM-DA受体介导调节室管膜细胞提供了形态学证据。     

首发精神分裂症患者抗N-甲基-D-天冬氨酸受体抗体和内源性皮质醇水平的关系

目的:探讨首发精神分裂症患者血清抗N-甲基-D-天冬氨酸受体抗体(NMDAR-Ab)和尿液内源性皮质醇/肌酐水平的关系。方法:纳入符合美国精神障碍诊断与统计手册第5版诊断标准的首发精神分裂症患者166例,正常对照129例。采用阳性和阴性症状量表(PANSS)评估患者的精神病理症状;血清抗NMDAR-Ab水平应用酶联免疫吸附法检测(ELISA);收集12 h尿液,采用免疫荧光法检测皮质醇和肌酐浓度,计算皮质醇/肌酐比(CCR)。结果:精神分裂症组血清抗NMDAR-Ab水平、12 h尿皮质醇水平、CCR均高于正常对照组(均P<0.001)。精神分裂症组的抗NMDAR-Ab水平与PANSS的阳性症状(r=0.22)、阴性症状(r=0.23)得分和总分(r=0.26)正相关(均P<0.05),与CCR正相关(r=0.30,P<0.001);正常对照组抗NMDAR-Ab水平与CCR之间相关性无统计学意义(P>0.05)。结论:首发精神分裂症患者存在较高的抗NMDAR-Ab水平,并和皮质醇水平升高相关,提示自身免疫系统异常可能参与精神分裂症疾病的发生,而身体通过反馈调节促进...     

The specific NMDA receptor antagonist AP-7 attenuates focal ischemic brain injury

Pharmacologic blockade of excitatory amino acid receptors, especially the N-methyl-D-aspartate-preferring subclass of glutamate receptors, has been shown to reduce neuronal damage in models of global cerebral ischemia followed by reperfusion. The pharmacologic blockade at the NMDA receptor attenuates infarct size following permanent focal vascular occlusion in brain. Functional recovery is improved as well. These effects were seen with treatment begun 15 min following the stroke.     

大鼠创伤性脑损伤后星形胶质细胞的变化

目的：探讨大鼠创伤性脑损伤后星形胶质细胞的形态学变化及GFAP和NOS的表达情况。方法：采用大鼠自由落体脑损伤模型，伤后1、3、7d取脑切片，行Nissl染色以及GFAP免疫组化和NADPH—d组化单标记及双标记染色。结果：损伤区周围皮质GFAP阳性细胞胞体增大、突起增粗增长，GFAP阳性细胞数量与正常侧及对照组相比，伤后1d即有明显增加，伤后3d、7d数量持续增加；损伤侧海马CAI～3区和DG各层GFAP阳性细胞排列紊乱，胞体增大、突起增粗增长，GFAP阳性细胞数量与正常侧及对照组相比则无明显变化。损伤区周围皮质、损伤侧海马NOS阳性细胞数量明显增加。伤后3d损伤区周围皮质和损伤侧海马中GFAP与NOS双标细胞分别占GFAP阳性细胞的14．2％和13．4％左右。结论：大鼠创伤性脑损伤后大量的星形胶质细胞活化、GFAP表达增加并且部分转化为NOS阳性细胞，提示其参与了脑组织的损伤与修复过程。     

NMDA and age dependent cerebral hemodynamics after traumatic brain injury.

Activation of N-methyl-D-aspartate (NMDA) glutamatergic receptors elicits cerebrovascular dilation, may couple local cerebral metabolism to blood flow but contribute to excitotoxic neuronal cell death. While cerebral hemodynamics following traumatic brain injury may correlate with neurologic status, the role of NMDA vascular activity is uncertain in the sequelae of brain injury. NMDA dilation was impaired following fluid percussion brain injury (FPI) in an age dependent manner in the pig and the newly described opioid nociceptin/orphanin FQ (NOC/ oFQ) contributes to such impairment via the cyclooxygenase dependent generation of superoxide. Further, hypotensive pial artery dilation (PAD) was blunted after FPI but partially protected by pretreatment with the NMDA antagonist MK801. Cerebral blood flow (CBF) was reduced during normotension by FPI, further reduced by hypotension, but both were partially protected by MK801 in the newborn. In contrast, blunted hypotensive PAD was protected significantly less by MK801 in the juvenile pig. Similarly, MK801 had less protective effect on normotensive and hypotensive CBF values post FPI in the juvenile. These data indicate that NMDA receptor activation contributes to impaired hypotensive cerebral hemodynamics following FPI in an age dependent manner. Further, these data suggest that NMDA receptor activation, NOC/oFQ, and prostaglandins dynamically interact to impair cerebral hemodynamics following FPI.     

Pathogenesis of hippocampal neuronal death after hypoxia-ischemia changes during brain development

Transient hypoxia-ischemia (HI) leads to delayed neuronal death in both mature and immature neurons but the underlying mechanisms are not fully understood. To understand whether the pathogenesis of HI-induced neuronal death is different between mature and immature neurons, we used a rat HI model at postnatal days 7 (P7), 15 (P15), 26 (P26) and 60 (P60) in order to investigate ultrastructural changes and active caspase-3 distribution in HI-injured neurons as a function of developmental age. In P7 pups, despite more than 95% of HI-injured neurons highly expressing active caspase-3, most of these active caspase-3-positive neurons revealed mixed features of apoptosis and necrosis (a chimera type) under electron microscopy (EM). Classical apoptosis was observed only in small populations of HI-injured P7 neurons. Furthermore, in rats older than P7, most HI-injured neurons displayed features of necrotic cell death under EM and, concomitantly, active caspase-3-positive neurons after HI declined dramatically. Classical apoptosis after HI was rarely found in neurons older than P15. In P60 rats, virtually all HI-injured neurons showed the shrinkage necrotic morphology under EM and were negative for active caspase-3. These results strongly suggest that pathogenesis of HI-induced neuronal death is shifting from apoptosis to necrosis during brain development.     

Roles for the pro-neurotrophin receptor sortilin in neuronal development, aging and brain injury

Neurotrophins are essential for development and maintenance of the vertebrate nervous system. Paradoxically, although mature neurotrophins promote neuronal survival by binding to tropomyosin receptor kinases and p75 neurotrophin receptor (p75(NTR)), pro-neurotrophins induce apoptosis in cultured neurons by engaging sortilin and p75(NTR) in a death-signaling receptor complex. Substantial amounts of neurotrophins are secreted in pro-form in vivo, yet their physiological significance remains unclear. We generated a sortilin-deficient mouse to examine the contribution of the p75(NTR)/sortilin receptor complex to neuronal viability. In the developing retina, Sortilin 1 (Sort1)(-/-) mice showed reduced neuronal apoptosis that was indistinguishable from that observed in p75(NTR)-deficient (Ngfr(-/-)) mice. To our surprise, although sortilin deficiency did not affect developmentally regulated apoptosis of sympathetic neurons, it did prevent their age-dependent degeneration. Furthermore, in an injury protocol, lesioned corticospinal neurons in Sort1(-/-) mice were protected from death. Thus, the sortilin pathway has distinct roles in pro-neurotrophin-induced apoptotic signaling in pathological conditions, but also in specific stages of neuronal development and aging.     

Detecting changes in neuronal activities induced by N-methyl-D-aspartate receptor blockade using non-linear dynamics techniques.

The dynamics of N-methyl-D-aspartate receptor blockade-induced transitions between two types of intracellularly recorded spontaneous membrane potential oscillation from cat thalamic neurons have been studied using non-linear dynamics techniques. We report that, as previously predicted by theoretical studies, the number of degrees of freedom of these oscillations (the minimal number of independent variables governing the activity) is small, i.e. they are low dimensional. The N-methyl-D-aspartate receptor antagonists DL-2-amino-5-phosphono-valeric acid and ketamine, which transformed one type of oscillation into another, decreased the calculated dimension. DL-2-Amino-5-phosphono-valeric acid had no effect on the dimension when Mg2+ was present in the perfusion medium. The decrease in dimension was gradual and its time-course had a sigmoidal shape. It is suggested that the application of the machinery of dynamical systems theory might help to detect and monitor drug-induced membrane potential state transitions and to identify the factors underlying membrane potential oscillations.     

MK-801对新生大鼠脑外伤后神经元凋亡的影响

目的：探讨N-甲基-D-天冬氨酸(NMDA)受体拮抗剂MK-801对新生大鼠创伤性脑外伤(traumatic brain injury,TBI)后神经元凋亡的影响。方法：建立新生7 d大鼠顶叶皮质挫伤模型,在TBI前30 min、TBI后即刻、TBI后30 min分别给予腹腔注射MK-8011 mg/kg,在TBI后24 h取脑,连续切片,行H-E染色和Caspase-3免疫组化染色,检测脑神经元细胞的损伤和凋亡。结果：MK-801三组不同时间用药组与TBI组相比,在创伤同侧的扣带皮质、顶叶皮质和丘脑神经元凋亡细胞数减少,有显著性差异。其中TBI后即刻用MK-801治疗效果最好。结论：MK-80l能明显减少TBI后神经元的凋亡。     

Alterations in neuronal calcium levels are associated with cognitive deficits after traumatic brain injury

Traumatic brain injury (TBI) survivors often suffer from a post-traumatic syndrome with deficits in learning and memory. Calcium (Ca(2+)) has been implicated in the pathophysiology of TBI-induced neuronal death. However, the role of long-term changes in neuronal Ca(2+) function in surviving neurons and the potential impact on TBI-induced cognitive impairments are less understood. Here we evaluated neuronal death and basal free intracellular Ca(2+) ([Ca(2+)](i)) in acutely isolated rat CA3 hippocampal neurons using the Ca(2+) indicator, Fura-2, at seven and thirty days after moderate central fluid percussion injury. In moderate TBI, cognitive deficits as evaluated by the Morris Water Maze (MWM), occur after injury but resolve after several weeks. Using MWM paradigm we compared alterations in [Ca(2+)](i) and cognitive deficits. Moderate TBI did not cause significant hippocampal neuronal death. However, basal [Ca(2+)](i) was significantly elevated when measured seven days post-TBI. At the same time, these animals exhibited significant cognitive impairment (F(2,25)=3.43, p<0.05). When measured 30 days post-TBI, both basal [Ca(2+)](i) and cognitive functions had returned to normal. Pretreatment with MK-801 blocked this elevation in [Ca(2+)](i) and also prevented MWM deficits. These studies provide evidence for a link between elevated [Ca(2+)](i) and altered cognition. Since no significant neuronal death was observed, the alterations in Ca(2+) homeostasis in the traumatized, but surviving neurons may play a role in the pathophysiology of cognitive deficits that manifest in the acute setting after TBI and represent a novel target for therapeutic intervention following TBI.     

Dimethylsulfoxide enhances CNS neuronal plasma membrane resealing after injury in low temperature or low calcium

The inability to repair the damaged membrane may be one of the key mechanisms underlying the severe neuronal degeneration and overall functional loss seen in in vivo spinal cord injury and traumatic axonal injury in blunt head trauma. Promoting membrane resealing following damage may therefore constitute a potential effective therapeutic intervention in treating head trauma and spinal cord injuries. In our previous studies, we have shown that the axolemma failed to reseal following transection in clinically related situations, such as low extracellular calcium and low temperature. Our current studies indicate that DMSO is capable of rendering significant improvement in guinea pig axonal membrane resealing following transection in both 0.5 mM [Ca(2+)](0) and 25 degrees C situations. This was demonstrated physiologically by monitoring membrane potential recovery and anatomically by conducting HRP-exclusion assays 60 minutes after injury. Further, we have shown that the addition of DMSO in normal Krebs' solution (2 mM [Ca(2+)](0) and 37 degrees C) resulted in a decrease in membrane repair following injury. This indicates that DMSO-mediated membrane repair is sensitive to temperature and calcium. This study suggests the role of DMSO in axonal membrane resealing in clinically relevant conditions and raises the possibility of using DMSO in combination with other more established therapies in spinal cord injury treatment.