Objective The aim of this study is to investigate whether microwave exposure would affect the N-methyl-D-aspartate receptor(NMDAR) signaling pathway to establish whether this plays a role in synaptic plasticity impair...Objective The aim of this study is to investigate whether microwave exposure would affect the N-methyl-D-aspartate receptor(NMDAR) signaling pathway to establish whether this plays a role in synaptic plasticity impairment. Methods 48 male Wistar rats were exposed to 30 m W/cm2 microwave for 10 min every other day for three times. Hippocampal structure was observed through H&E staining and transmission electron microscope. PC12 cells were exposed to 30 m W/cm2 microwave for 5 min and the synapse morphology was visualized with scanning electron microscope and atomic force microscope. The release of amino acid neurotransmitters and calcium influx were detected. The expressions of several key NMDAR signaling molecules were evaluated. Results Microwave exposure caused injury in rat hippocampal structure and PC12 cells, especially the structure and quantity of synapses. The ratio of glutamic acid and gamma-aminobutyric acid neurotransmitters was increased and the intracellular calcium level was elevated in PC12 cells. A significant change in NMDAR subunits(NR1, NR2 A, and NR2B) and related signaling molecules(Ca2+/calmodulin-dependent kinase II gamma and phosphorylated c AMP-response element binding protein) were examined. Conclusion 30 m W/cm2 microwave exposure resulted in alterations of synaptic structure, amino acid neurotransmitter release and calcium influx. NMDAR signaling molecules were closely associated with impaired synaptic plasticity.展开更多
This study examined the effects of clinically relevant concentrations of isoflurane on the amplitude of NMDA receptor current(INMDA)and the expression of cytochrome C in cultured developing rat hippocampal neurons.The...This study examined the effects of clinically relevant concentrations of isoflurane on the amplitude of NMDA receptor current(INMDA)and the expression of cytochrome C in cultured developing rat hippocampal neurons.The hippocampi were dissected from newborn Sprague-Dawley rats.Hip-pocampal neurons were primarily cultured for 5 days and then treated with different concentrations of isoflurane [(0.25,0.5,0.75,1 minimum alveolar concentration(MAC))].The peak of INMDA was recorded by means of the whole cell patch clamp technique.The cytochrome C level was detected by Western blotting and quantitative real-time PCR.Our results showed that isoflurane(0.25,0.5,0.75 and 1 MAC)potentiated the amplitude of INMDA by(116±8.8)%,(122±11.7)%,(135±14.3)% and(132±14.6)%,respectively,and isoflurane increased the mRNA expression of cytochrome C in a con-centration-dependent manner.The cytochrome C mRNA expression reached a maximum after 0.5 MAC isoflurane stimulation for 6 h(P<0.05).It was concluded that isoflurane enhances the expression of cy-tochrome C in cultured rat hippocampal neurons,which may be mediated by facilitation of NMDA re-ceptor.展开更多
Objective: To study the effect of glycine site/NMDA (N-methyl-D-aspartate) receptor antagonist MRZ2/576 on the conditioned place preference (CPP) and locomotor activity induced by morphine in mice. Methods: Different ...Objective: To study the effect of glycine site/NMDA (N-methyl-D-aspartate) receptor antagonist MRZ2/576 on the conditioned place preference (CPP) and locomotor activity induced by morphine in mice. Methods: Different doses (1.25, 2.5 and 5 mg/kg, i.p.) of MRZ2/576 were used to evaluate the effect of MRZ2/576 on the acquisition and expression of CPP induced by morphine (5 mg/kg) in mice. In addition, we examined the locomotor activity of mice in conditioning and testing phase of CPP paradigm. Results: MRZ2/576 alone could not establish place preference, but a 5 mg/kg dose of MRZ2/576 could block both acquisition and expression of morphine-induced CPP. In testing phase of CPP, there was no statistical difference for locomotor activity between the groups; injection of MRZ2/576 showed a dose-dependent decrease of locomotor activity on both control and morphine-treated mice, especially 5 mg/kg of MRZ2/576 significantly suppressed the locomotor activity of mice. Conclusion: Based on the present results, we assume that MRZ2/576 can antagonize the rewarding effect of morphine, suggesting that this glycine site/NMDA receptor antagonist could be used to treat addictions due to its light side effect profile.展开更多
Summary: To investigate the exact mechanism of epileptogenesis induced by coriaria lactone (CL), the effect of CL on NMDA receptor mediated current (IAsp) in rat hippocampal CA1 neu- rons was investigated by using nys...Summary: To investigate the exact mechanism of epileptogenesis induced by coriaria lactone (CL), the effect of CL on NMDA receptor mediated current (IAsp) in rat hippocampal CA1 neu- rons was investigated by using nystatin perforated whole-cell patch clamp. 10-6-10-4 mol/L Asp acted on NMDA receptors and elicited an inward current (IAsp) at a holding potential (VH) of -40 mV in presence of 10-6 mol/L glycine and absence of Mg2+ extracellularly. CL enhanced NMDA receptor mediated current induced by Asp, but had no effect on threshold concentration, EC50, Hill coefficient as well as maximal-effect concentration and reversal potential of IAsp. The effect had no relationship with holding potential. These results showed that CL could enhance NMDA receptor mediated current to increase [Ca2+]i of neurons by acting on Gly site, thereby inducing epilepsy.展开更多
Objective To study the effect of salicylate on the expression and function of NMDA receptors in spiral ganglion neurons (SGNs). Methods The mRNA of NR1 subunit of NMDA receptor in modiolus tissues were detected by Rea...Objective To study the effect of salicylate on the expression and function of NMDA receptors in spiral ganglion neurons (SGNs). Methods The mRNA of NR1 subunit of NMDA receptor in modiolus tissues were detected by Real time fluorescence quantitative PCR (FQ-PCR). NMDA receptor whole-cell currents were recorded using patch clamp in acute isolated SGNs. Results Compared with the control group, salicylate significantly increased the mRNA level of NR1 subunit in SGNs. NMDA of concentrations ranging from 0.1 mM to 10 mM evoked no current in SGNs. NMDA (0.1mM and 0.5 mM) applied with salicylate (5 mM), however, induced inward currents (212.6±15.2pA, n=5; 607.9±44.3pA, n=5) in a dose-dependent manner, which could be inhibited by APV. Salicylate alone did not produce any current in SGNs. Conclusion Salicylate increases the expression of NMDA receptors and facilitates the currents mediated by NMDA receptors in SGNs.展开更多
Major depressive disorder(MDD)is a common neuropsychiatric disorder characterized by diverse symptoms.There are big limitations of clinic medicine which highlighted an urgent and clear need for more efficacious and fa...Major depressive disorder(MDD)is a common neuropsychiatric disorder characterized by diverse symptoms.There are big limitations of clinic medicine which highlighted an urgent and clear need for more efficacious and faster-acting therapeutic agents to treat patients with MDD,especially those who are refractory to the traditional antidepressants.In the present study,we assessed a novel compound,YY-21,from timosaponin B-Ⅲ derived from sarsasapogenin of Anemarrhenae Rhizoma.We found that YY-21 obviously increased presynaptic glutamate release and enhanced long-term synaptic activity within 10 min as determined by excitatory postsynaptic current(EPSC) and field excitatory postsynaptic potential(fEPSP) in medial prefrontal cortex(mPFC) slices.YY-21 demonstrated anxiolytic-like effects following acute administration in animals and reversed the depressivelike and anxiety phenotypes induced by chronic unpredictable mild stress(CMS) with a relatively fast therapeutic onset.Our mechanism research reveals that NMDA receptors and two-pore domain potassium(K2P)(TREK1) channels emerged as new drug targets for faster acting antidepressants.K2 P channels generate leak currents that are responsible the maintenance of resting membrane potential.They are potential targets for the treatment of multiple diseases.Here we identify TKDC,an inhibitor of the TREK subfamily,including TREK1,TREK2 and TRAAK channels.Using TKDC as a chemical probe,a combined study of computations,mutagenesis,and electrophysiology reveal an allosteric ligand-binding site in the extracellular cap of the channels.The molecular dynamics simulations suggest that ligand-induced allosteric conformational transitions cause a blockage of the ion conductive pathway.The identification of the extracellular ligand-binding site is confirmed by the discovery of new inhibitors targeting this site using virtual screening.These results suggest that the extracellular cap of a K2P channel can act as a new allosteric site and may serve as a direct drug target.展开更多
The 4,5-dioxo-4,5-dihydro-1H-pyrrolo(2,3-f)quinoline-2,7,9-tricarboxylic acid 2-ethyl ester 7,9-dimethyl ester (PQQE) was synthesized on the basis of Pyrroloquinoline quinine (PQQ). 99m Tc-PQQE was prepared using stan...The 4,5-dioxo-4,5-dihydro-1H-pyrrolo(2,3-f)quinoline-2,7,9-tricarboxylic acid 2-ethyl ester 7,9-dimethyl ester (PQQE) was synthesized on the basis of Pyrroloquinoline quinine (PQQ). 99m Tc-PQQE was prepared using stannous fluoride (SnF 2 ) as reducing agent. Biological characteristics of 99m Tc-PQQE include lipophilic and the charge properties were compared to 99m Tc-PQQ. The biodistributions of 99m Tc-PQQE in mice and brain regional distribution were performed. In vivo distribution of 99m Tc-PQQE in mice indicates that the concentration ratio of drug and blood increases steadily over time. The major radioactivity may be metabolized by the hepatic and renal system. The elimination-phase half-time (t1/2β) results indicate that the residence time of 99m Tc-PQQE (203.92) in the body is twice as long as 99m Tc-PQQ (100.45). The uptake of 99m Tc-PQQE in brain was improved due to the ameliorating of charge and lipophilicity. The highest total regional brain uptake of 99m Tc-PQQE was in the frontal lobe and hippocampus, where the NMDA receptor is very abundant. 99m Tc-PQQE had a good target to nontarget ratio (hippocampus/cerebellum) which preserved a higher value (peak 4.0 at 120 min) from 60 min to 180 min after injection. In vitro autoradiographic results are in close agreement with the regional brain map. The enrichment can be blocked by N-methyl-D-aspartate receptor (NMDAR) redox modulatory site antagonists-ebselen (EB). This work suggests that 99m Tc-PQQE has some specific targeting to the NMDA receptor.展开更多
Adult-born neurons undergo a transient period of plasticity during their integration into the neural circuit.This transient plasticity may involve NMDA receptors containing NR2B,the major subunit expressed at early de...Adult-born neurons undergo a transient period of plasticity during their integration into the neural circuit.This transient plasticity may involve NMDA receptors containing NR2B,the major subunit expressed at early developmental stages.The main objective of the present study was to investigate the effects of NR2B gene knockdown on the functional integration of the adult-born granule cells generated from the subgranule zone (SGZ) in the hippocampus.The small interfering RNA (siRNA) was used to knock down the NR2B gene in the adult-born hippocampal neurons.In the functional integration test,the mice were exposed to a novel environment (open field arena),and the expression of c-fos was immunohistochemically detected in the hippocampus.After exposure to the novel environment,siRNA-NR2B mice were significantly different from control mice in either the number of squares or the number of rears they crossed,showing decreased horizontal and vertical activity (P<0.05).Moreover,the c-fos expression was increased in both control and siRNA-NR2B mice after open field test.But,it was significantly lower in siRNA-NR2B neurons than in control neurons.It was concluded that the neural activity of newborn neurons is regulated by their own NR2B-containing NMDA glutamate receptors during a short,critical period after neuronal birth.展开更多
The pharmacologic characteristics of ^(99)Tc^m-N-ethyl-N_2S_2-memantine,an NMDA receptor imaging agent,was investigated.It was prepared by a one-step reaction from N-ethyl-N_2S_2-memantine.The affinity and specificity...The pharmacologic characteristics of ^(99)Tc^m-N-ethyl-N_2S_2-memantine,an NMDA receptor imaging agent,was investigated.It was prepared by a one-step reaction from N-ethyl-N_2S_2-memantine.The affinity and specificity were determined by radio-ligand receptor binding assay(RRA).Biodistribution in vivo in mice was performed.The results showed that ^(99)Tc^m-N-ethyl-N_2S_2-memantine bound to a single site on NMDA receptor with a K_d of 584.32 nmol/L and a B_(max)of 267.05 nmol/mg.A competitive analysis showed that such specific binding could be inhibited by specific inhibitors of NMDA receptor,such as ketamine and(+)-MK-801.The biodistribution exhibited rapid uptake and favorable retention in mice brains.The major radioactivity was metabolized by the hepatic system.A two-compartment model of C=4.49e^(-0.083t)+ 1.42e^(-0.0016t)was established,and the half life was 8.35 min in blood.In conclusion,the new radio-ligand ^(99)Tc^m-N-ethyl-N_2S_2-Memantine has a moderate affinity and specific binding to NMDA receptor,and can easily cross the blood-brain barrier(BBB).Therefore,it may be a potential NMDA receptor imaging agent.展开更多
NMDA receptor channels play a significant role in learning and memory and their dysfunction can cause neuronal cell death leading to dementia. Research had shown that lipids change the risk for dementia, especially so...NMDA receptor channels play a significant role in learning and memory and their dysfunction can cause neuronal cell death leading to dementia. Research had shown that lipids change the risk for dementia, especially some omega-3 lipids appear to lower Alz-heimer’s risk, yet only limited research exists on the modulation of NMDA receptor channels by lipids. Here we review recent literature concerning molecular determinants that influence the NMDA receptor channel gating via membrane lipids and fatty acids with profound significance for understanding how altered NMDA signalling leads to neuronal cell death linked to age-related dementia’s. Future discovery of lipid-like modulators of NMDA receptor function offer the potential for the development of new bioceu-ticals and affordable nutritional supplements to combat neuronal degeneration as well as to promote well being and healthy aging.展开更多
Nerve agents are used in civil wars and terrorist attacks,posing a threat to public safety.Acute exposure to nerve agents such as soman(GD)causes serious brain damage,leading to death due to intense seizures induced b...Nerve agents are used in civil wars and terrorist attacks,posing a threat to public safety.Acute exposure to nerve agents such as soman(GD)causes serious brain damage,leading to death due to intense seizures induced by acetylcholinesterase inhibition and neuronal injury resulting from increased excitatory amino-acid levels and neuroinflammation.However,data on the anticonvulsant and neuroprotective efficacies of currently-used countermeasures are limited.Here,we evaluated the potential effects of transient receptor vanilloid 4(TRPV4)in the treatment of soman-induced status epilepticus(SE)and secondary brain injury.We demonstrated that TRPV4 expression was markedly up-regulated in rat hippocampus after soman-induced seizures.Administration of the TRPV4 antagonist GSK2193874 prior to soman exposure significantly decreased the mortality rate in rats and reduced SE intensity.TRPV4-knockout mice also showed lower incidence of seizures and higher survival rates than wild-type mice following soman exposure.Further in vivo and in vitro experiments demonstrated that blocking TRPV4 prevented NMDA receptor-mediated glutamate excitotoxicity.The protein levels of the NLRP3 inflammasome complex and its downstream cytokines IL-1βand IL-18 increased in soman-exposed rat hippocampus.However,TRPV4 inhibition or deletion markedly reversed the activation of the NLRP3 inflammasome pathway.In conclusion,our study suggests that the blockade of TRPV4 protects against soman exposure and reduces brain injury following SE by decreasing NMDA receptor-mediated excitotoxicity and NLRP3-mediated neuroinflammation.To our knowledge,this is the first study regarding the“dual-switch”function of TRPV4 in the treatment of soman intoxication.展开更多
Glutamate-induced neuronal damage is mainly caused by overactivation of N-methyl-D-aspartate(NMDA)receptors.Conversely,normal physiological brain function and neuronal survival require adequate activation of NMDA rece...Glutamate-induced neuronal damage is mainly caused by overactivation of N-methyl-D-aspartate(NMDA)receptors.Conversely,normal physiological brain function and neuronal survival require adequate activation of NMDA receptors.Studies have revealed that NMDA receptor-induced neuronal death or survival is mediated through distinct subset of NMDA receptors triggering different intracellular signaling pathways.Here we discuss recent advances in the characterization of NMDA receptors in neuronal protection,emphasizing subunit-specific role,which contributes to temporal-spatial distribution,subcellular localization and diverse channel properties of NMDA receptors.展开更多
Memory impairment in children is an ongoing issue worldwide related to a learning disability. This neurobiological condition has been suggested to associate with bisphenol A (BPA) exposure during pregnancy. BPA is an ...Memory impairment in children is an ongoing issue worldwide related to a learning disability. This neurobiological condition has been suggested to associate with bisphenol A (BPA) exposure during pregnancy. BPA is an inorganic compound used to produce polycarbonate plastics and epoxy resins. We conduct this study to investigate the effects of prenatal BPA exposure on the level of the N-methyl-D-aspartate (NMDA) receptor subunits, synaptic markers of the hippocampus and neurobehavioral outcomes in rats. The pregnant rats were given a daily dose of 5 mg/kg and 50 mg/kg of BPA with 0.5% Tween 80 orally from gestation day 2 until 21 (GD21). The level of GluN2A, GluN2B, PSD-95 and synapsin I in the hippocampus and its neurobehaviour outcomes were quantified and evaluated in the male foetus and adolescent rat. Prenatal BPA exposure reduced GluN2A, GluN2B, synapsin I and PSD-95 (Postsynaptic Density-95) in the male foetus and adolescent rat hippocampus compared to the control group. The prenatal BPA exposed rats demonstrated anxiety-related behaviour and impairment in aversive and spatial memory. The findings suggested that the impairment in neurobehavioral performance may inhibit the signalling pathway in the NMDA receptor subunits in the male foetus rat hippocampus leading to learning and memory deficits when reaching adolescence.展开更多
The rhizome of Gastrodia elata(GE), a herb medicine, has been used for treatment of neuronal disorders in Eastern Asia for hundreds of years. Parishin C is a major ingredient of GE. In this study, the i.c.v. injection...The rhizome of Gastrodia elata(GE), a herb medicine, has been used for treatment of neuronal disorders in Eastern Asia for hundreds of years. Parishin C is a major ingredient of GE. In this study, the i.c.v. injection of soluble Aβ1–42oligomers model of LTP injury was used. We investigated the effects of parishin C on the improvement of LTP in soluble Aβ1–42oligomer–injected rats and the underlying electrophysiological mechanisms. Parishin C(i.p. or i.c.v.) significantly ameliorated LTP impairment induced by i.c.v. injection of soluble Aβ1–42oligomers. In cultured hippocampal neurons,soluble Aβ1–42oligomers significantly inhibited NMDAR currents while not affecting AMPAR currents and voltage-dependent currents. Pretreatment with parishin C protected NMDA receptor currents from the damage induced by Aβ. In summary, parishin C improved LTP deficits induced by soluble Aβ1–42oligomers. The protection by parishin C against Aβ-induced LTP damage might be related to NMDA receptors.展开更多
N-methyl-D-aspartate receptors(NMDARs) containing different GluN2 subunits play distinct roles in synaptic plasticity.Such differences may not only be determined by the channel properties, but also by differential sur...N-methyl-D-aspartate receptors(NMDARs) containing different GluN2 subunits play distinct roles in synaptic plasticity.Such differences may not only be determined by the channel properties, but also by differential surface distribution and synaptic localization.In the present study, using a Cy3-conjugated Fab fragment of the GFP antibody to label surface-located GluN2 subunits tagged with GFP at the N-terminus, we observed the membrane distribution patterns of GluN2A- or GluN2B-containing NMDARs in cultured rat hippocampal neurons.We found that surface NMDARs containing GluN2 A, but not those containing GluN2 B, were inclined to cluster at DIV7.Swapping the carboxyl termini of the GluN2 subunits completely reversed these distribution patterns.In addition, surface NMDARs containing GluN2 A were preferentially associated with PSD-95.Taken together, the results of our study suggest that the clustering distribution of GluN2 Acontaining NMDARs is determined by the GluN2 A C-terminus, and its interaction with PSD-95 plays an important role in this process.展开更多
Purpose To identify the structure and the function of NMDA receptors, to understand the modulatory mechanism of some endogenous and exogenous compounds on NMDA receptors, and to provide theoretical basis for developin...Purpose To identify the structure and the function of NMDA receptors, to understand the modulatory mechanism of some endogenous and exogenous compounds on NMDA receptors, and to provide theoretical basis for developing new drugs that modulate NMDA receptors Data sources A total of 24 originally identified articles were selected Study selection A total of 24 articles were selected from several hundred original articles or reviews. The content of selected articles are in accordance with our purpose and the authors are authorized scientists in the study on NMDA receptors.Data extraction After careful review of the selected papers, the meaningful results and conclusions were extracted using scientific criteria and our experience in the research of NMDA receptors.Results NMDA receptor contains at least five subunits. They were designated as the NR1 (ζ1), NR2A (ε1), NR2B (ε2), NR2C (ε3), and NR2D (ε4). A unique feature of NMDA receptor is the requirement for both glutamate and the co agnist glycine for the efficient gating. NMDA receptor is modulated by a number of endogenous and exogenous compounds. Mg 2+ not only blocks the NMDA channel in a voltage dependent manner but also potentiates NMDA induced responses at positive membrane potentials. Na +, K + and Ca 2+ not only pass through the NMDA receptor channel but also modulate the activity of NMDA receptors. Zn 2+ blocks the NMDA current in a noncompetitive and a voltage independent manner. It has been demonstrated that polyamines do not directly activate NMDA receptors, but instead act to potentiate or inhibit glutamate mediated responses. The activity of NMDA receptors is also strikingly sensitive to the changes in H + concentration, and partially inhibited by the ambient concentration of H + under physiological conditions.Conclusions NMDA receptors are glutamate regulated by ion channels that are permeable to Ca 2+ , Na +, K + and are sensitive to voltage dependent Mg 2+ block This channel complex contributes to excitatory synaptic transmission at sites throughout the brain and the spinal cord,and is modulated by a number of endogenous and exogenous compounds NMDA receptors play a key role in wide range of physiologic and pathologic processes Five NMDA receptor subunits have now been characterized in both rat and mouse展开更多
Activation of N-methyl-D-aspartate receptors(NMDARs)mediates changes in the phosphorylation status of the glutamate receptors themselves.Previous studies have indicated that during synaptic activity,tyrosine kinases(S...Activation of N-methyl-D-aspartate receptors(NMDARs)mediates changes in the phosphorylation status of the glutamate receptors themselves.Previous studies have indicated that during synaptic activity,tyrosine kinases(Src and Fyn)or phosphatases(PTPαand STEP)are involved in regulating the phosphorylation of NMDARs.In this study,we used immunoblotting to investigate the role of an NMDAR subpopulation on the phosphorylation level of the GluN2B subunit at the Y1336 and Y1472sites in rat brain slices after NMDA treatment.We found that NMDA stimulation dramatically decreased the phosphorylation level of GluN2B at Y1472 in a dose-and time-dependent manner,but not at Y1336.Extrasynaptic NMDAR activation did not reduce the phosphorylation of GluN2B at Y1472.In addition,ifenprodil,a selective antagonist of GluN2Bcontaining NMDARs,did not abolish the decreased phosphorylation of GluN2B at Y1472 triggered by NMDA.These results suggest that the activation of synaptic GluN2A-containing NMDARs is required for the decreased phosphorylation of GluN2B at Y1472that is induced by NMDA treatment in rat brain slices.展开更多
Accumulating evidence indicates that the synaptic activation of N-methyl-D-aspartate receptors(NMDARs) has a neuroprotective effect on neurons. Our previous study demonstrated that APPL1(adaptor protein containing ple...Accumulating evidence indicates that the synaptic activation of N-methyl-D-aspartate receptors(NMDARs) has a neuroprotective effect on neurons. Our previous study demonstrated that APPL1(adaptor protein containing pleckstrin homology domain, phosphotyrosinebinding domain, and leucine zipper motif) mediates the synaptic activity-dependent activation of PI3K-Akt signaling via coupling this pathway with NMDAR-PSD95(postsynaptic density protein 95) complexes. However, the molecular mechanism underlying this process is still unknown. In the present study, we investigated the interaction of APPL1 with PSD95 using co-immunocytochemical staining and western blotting. We found that the PDZ2 domain of PSD95 is a binding partner of APPL1.Furthermore, we identified serine 707 of APPL1, a predicted phosphorylation site within the PDZ-binding motif at the C-terminus, as critical for the binding of APPL1 to PSD95, as well as for activation of the Akt signaling pathway during synaptic activity. This suggests that serine707 of APPL1 is a potential phosphorylation site and may be involved in regulating the neuroprotective Akt signaling pathway that depends on synaptic NMDAR activity.展开更多
基金supported by the National Natural Science Foundation of China(No.81172620)
文摘Objective The aim of this study is to investigate whether microwave exposure would affect the N-methyl-D-aspartate receptor(NMDAR) signaling pathway to establish whether this plays a role in synaptic plasticity impairment. Methods 48 male Wistar rats were exposed to 30 m W/cm2 microwave for 10 min every other day for three times. Hippocampal structure was observed through H&E staining and transmission electron microscope. PC12 cells were exposed to 30 m W/cm2 microwave for 5 min and the synapse morphology was visualized with scanning electron microscope and atomic force microscope. The release of amino acid neurotransmitters and calcium influx were detected. The expressions of several key NMDAR signaling molecules were evaluated. Results Microwave exposure caused injury in rat hippocampal structure and PC12 cells, especially the structure and quantity of synapses. The ratio of glutamic acid and gamma-aminobutyric acid neurotransmitters was increased and the intracellular calcium level was elevated in PC12 cells. A significant change in NMDAR subunits(NR1, NR2 A, and NR2B) and related signaling molecules(Ca2+/calmodulin-dependent kinase II gamma and phosphorylated c AMP-response element binding protein) were examined. Conclusion 30 m W/cm2 microwave exposure resulted in alterations of synaptic structure, amino acid neurotransmitter release and calcium influx. NMDAR signaling molecules were closely associated with impaired synaptic plasticity.
基金supported by grants from the National Natural Science Foundation of China(No.30772086No.30901390)
文摘This study examined the effects of clinically relevant concentrations of isoflurane on the amplitude of NMDA receptor current(INMDA)and the expression of cytochrome C in cultured developing rat hippocampal neurons.The hippocampi were dissected from newborn Sprague-Dawley rats.Hip-pocampal neurons were primarily cultured for 5 days and then treated with different concentrations of isoflurane [(0.25,0.5,0.75,1 minimum alveolar concentration(MAC))].The peak of INMDA was recorded by means of the whole cell patch clamp technique.The cytochrome C level was detected by Western blotting and quantitative real-time PCR.Our results showed that isoflurane(0.25,0.5,0.75 and 1 MAC)potentiated the amplitude of INMDA by(116±8.8)%,(122±11.7)%,(135±14.3)% and(132±14.6)%,respectively,and isoflurane increased the mRNA expression of cytochrome C in a con-centration-dependent manner.The cytochrome C mRNA expression reached a maximum after 0.5 MAC isoflurane stimulation for 6 h(P<0.05).It was concluded that isoflurane enhances the expression of cy-tochrome C in cultured rat hippocampal neurons,which may be mediated by facilitation of NMDA re-ceptor.
基金Project supported by the National Basic Research Program (973) of China (No. 2003CB515402), and the Science and Technology Coun-cil of Zhejiang Province (No. 2005C23G2010166), China
文摘Objective: To study the effect of glycine site/NMDA (N-methyl-D-aspartate) receptor antagonist MRZ2/576 on the conditioned place preference (CPP) and locomotor activity induced by morphine in mice. Methods: Different doses (1.25, 2.5 and 5 mg/kg, i.p.) of MRZ2/576 were used to evaluate the effect of MRZ2/576 on the acquisition and expression of CPP induced by morphine (5 mg/kg) in mice. In addition, we examined the locomotor activity of mice in conditioning and testing phase of CPP paradigm. Results: MRZ2/576 alone could not establish place preference, but a 5 mg/kg dose of MRZ2/576 could block both acquisition and expression of morphine-induced CPP. In testing phase of CPP, there was no statistical difference for locomotor activity between the groups; injection of MRZ2/576 showed a dose-dependent decrease of locomotor activity on both control and morphine-treated mice, especially 5 mg/kg of MRZ2/576 significantly suppressed the locomotor activity of mice. Conclusion: Based on the present results, we assume that MRZ2/576 can antagonize the rewarding effect of morphine, suggesting that this glycine site/NMDA receptor antagonist could be used to treat addictions due to its light side effect profile.
基金This project was supported by a grant from the National Natural Science Foundation of China !(No. 39330210).
文摘Summary: To investigate the exact mechanism of epileptogenesis induced by coriaria lactone (CL), the effect of CL on NMDA receptor mediated current (IAsp) in rat hippocampal CA1 neu- rons was investigated by using nystatin perforated whole-cell patch clamp. 10-6-10-4 mol/L Asp acted on NMDA receptors and elicited an inward current (IAsp) at a holding potential (VH) of -40 mV in presence of 10-6 mol/L glycine and absence of Mg2+ extracellularly. CL enhanced NMDA receptor mediated current induced by Asp, but had no effect on threshold concentration, EC50, Hill coefficient as well as maximal-effect concentration and reversal potential of IAsp. The effect had no relationship with holding potential. These results showed that CL could enhance NMDA receptor mediated current to increase [Ca2+]i of neurons by acting on Gly site, thereby inducing epilepsy.
基金supported by a grant from National Nature Science Fund of China(No.81060082,30860098)Nature Science Fund of Guangxi(No.2011jjA40056)to Jiping Su
文摘Objective To study the effect of salicylate on the expression and function of NMDA receptors in spiral ganglion neurons (SGNs). Methods The mRNA of NR1 subunit of NMDA receptor in modiolus tissues were detected by Real time fluorescence quantitative PCR (FQ-PCR). NMDA receptor whole-cell currents were recorded using patch clamp in acute isolated SGNs. Results Compared with the control group, salicylate significantly increased the mRNA level of NR1 subunit in SGNs. NMDA of concentrations ranging from 0.1 mM to 10 mM evoked no current in SGNs. NMDA (0.1mM and 0.5 mM) applied with salicylate (5 mM), however, induced inward currents (212.6±15.2pA, n=5; 607.9±44.3pA, n=5) in a dose-dependent manner, which could be inhibited by APV. Salicylate alone did not produce any current in SGNs. Conclusion Salicylate increases the expression of NMDA receptors and facilitates the currents mediated by NMDA receptors in SGNs.
文摘Major depressive disorder(MDD)is a common neuropsychiatric disorder characterized by diverse symptoms.There are big limitations of clinic medicine which highlighted an urgent and clear need for more efficacious and faster-acting therapeutic agents to treat patients with MDD,especially those who are refractory to the traditional antidepressants.In the present study,we assessed a novel compound,YY-21,from timosaponin B-Ⅲ derived from sarsasapogenin of Anemarrhenae Rhizoma.We found that YY-21 obviously increased presynaptic glutamate release and enhanced long-term synaptic activity within 10 min as determined by excitatory postsynaptic current(EPSC) and field excitatory postsynaptic potential(fEPSP) in medial prefrontal cortex(mPFC) slices.YY-21 demonstrated anxiolytic-like effects following acute administration in animals and reversed the depressivelike and anxiety phenotypes induced by chronic unpredictable mild stress(CMS) with a relatively fast therapeutic onset.Our mechanism research reveals that NMDA receptors and two-pore domain potassium(K2P)(TREK1) channels emerged as new drug targets for faster acting antidepressants.K2 P channels generate leak currents that are responsible the maintenance of resting membrane potential.They are potential targets for the treatment of multiple diseases.Here we identify TKDC,an inhibitor of the TREK subfamily,including TREK1,TREK2 and TRAAK channels.Using TKDC as a chemical probe,a combined study of computations,mutagenesis,and electrophysiology reveal an allosteric ligand-binding site in the extracellular cap of the channels.The molecular dynamics simulations suggest that ligand-induced allosteric conformational transitions cause a blockage of the ion conductive pathway.The identification of the extracellular ligand-binding site is confirmed by the discovery of new inhibitors targeting this site using virtual screening.These results suggest that the extracellular cap of a K2P channel can act as a new allosteric site and may serve as a direct drug target.
基金Supported by National Natural Science Foundation of China(No.30770602)Natural Science Foundation of Jiangsu Province,China(Nos.BK2010157 and BK2011167)
文摘The 4,5-dioxo-4,5-dihydro-1H-pyrrolo(2,3-f)quinoline-2,7,9-tricarboxylic acid 2-ethyl ester 7,9-dimethyl ester (PQQE) was synthesized on the basis of Pyrroloquinoline quinine (PQQ). 99m Tc-PQQE was prepared using stannous fluoride (SnF 2 ) as reducing agent. Biological characteristics of 99m Tc-PQQE include lipophilic and the charge properties were compared to 99m Tc-PQQ. The biodistributions of 99m Tc-PQQE in mice and brain regional distribution were performed. In vivo distribution of 99m Tc-PQQE in mice indicates that the concentration ratio of drug and blood increases steadily over time. The major radioactivity may be metabolized by the hepatic and renal system. The elimination-phase half-time (t1/2β) results indicate that the residence time of 99m Tc-PQQE (203.92) in the body is twice as long as 99m Tc-PQQ (100.45). The uptake of 99m Tc-PQQE in brain was improved due to the ameliorating of charge and lipophilicity. The highest total regional brain uptake of 99m Tc-PQQE was in the frontal lobe and hippocampus, where the NMDA receptor is very abundant. 99m Tc-PQQE had a good target to nontarget ratio (hippocampus/cerebellum) which preserved a higher value (peak 4.0 at 120 min) from 60 min to 180 min after injection. In vitro autoradiographic results are in close agreement with the regional brain map. The enrichment can be blocked by N-methyl-D-aspartate receptor (NMDAR) redox modulatory site antagonists-ebselen (EB). This work suggests that 99m Tc-PQQE has some specific targeting to the NMDA receptor.
基金supported by the National Natural Science Foundation of China(No.81000537)
文摘Adult-born neurons undergo a transient period of plasticity during their integration into the neural circuit.This transient plasticity may involve NMDA receptors containing NR2B,the major subunit expressed at early developmental stages.The main objective of the present study was to investigate the effects of NR2B gene knockdown on the functional integration of the adult-born granule cells generated from the subgranule zone (SGZ) in the hippocampus.The small interfering RNA (siRNA) was used to knock down the NR2B gene in the adult-born hippocampal neurons.In the functional integration test,the mice were exposed to a novel environment (open field arena),and the expression of c-fos was immunohistochemically detected in the hippocampus.After exposure to the novel environment,siRNA-NR2B mice were significantly different from control mice in either the number of squares or the number of rears they crossed,showing decreased horizontal and vertical activity (P<0.05).Moreover,the c-fos expression was increased in both control and siRNA-NR2B mice after open field test.But,it was significantly lower in siRNA-NR2B neurons than in control neurons.It was concluded that the neural activity of newborn neurons is regulated by their own NR2B-containing NMDA glutamate receptors during a short,critical period after neuronal birth.
基金Supported by National Natural Science Foundation(No30770602)Jiangsu Natural Science Foundation(No BK2008111)
文摘The pharmacologic characteristics of ^(99)Tc^m-N-ethyl-N_2S_2-memantine,an NMDA receptor imaging agent,was investigated.It was prepared by a one-step reaction from N-ethyl-N_2S_2-memantine.The affinity and specificity were determined by radio-ligand receptor binding assay(RRA).Biodistribution in vivo in mice was performed.The results showed that ^(99)Tc^m-N-ethyl-N_2S_2-memantine bound to a single site on NMDA receptor with a K_d of 584.32 nmol/L and a B_(max)of 267.05 nmol/mg.A competitive analysis showed that such specific binding could be inhibited by specific inhibitors of NMDA receptor,such as ketamine and(+)-MK-801.The biodistribution exhibited rapid uptake and favorable retention in mice brains.The major radioactivity was metabolized by the hepatic system.A two-compartment model of C=4.49e^(-0.083t)+ 1.42e^(-0.0016t)was established,and the half life was 8.35 min in blood.In conclusion,the new radio-ligand ^(99)Tc^m-N-ethyl-N_2S_2-Memantine has a moderate affinity and specific binding to NMDA receptor,and can easily cross the blood-brain barrier(BBB).Therefore,it may be a potential NMDA receptor imaging agent.
文摘NMDA receptor channels play a significant role in learning and memory and their dysfunction can cause neuronal cell death leading to dementia. Research had shown that lipids change the risk for dementia, especially some omega-3 lipids appear to lower Alz-heimer’s risk, yet only limited research exists on the modulation of NMDA receptor channels by lipids. Here we review recent literature concerning molecular determinants that influence the NMDA receptor channel gating via membrane lipids and fatty acids with profound significance for understanding how altered NMDA signalling leads to neuronal cell death linked to age-related dementia’s. Future discovery of lipid-like modulators of NMDA receptor function offer the potential for the development of new bioceu-ticals and affordable nutritional supplements to combat neuronal degeneration as well as to promote well being and healthy aging.
基金the Special Fund for Military Medical Science(AWS15J007 and BWS16J007)the National Natural Science Foundation of China(81703505).
文摘Nerve agents are used in civil wars and terrorist attacks,posing a threat to public safety.Acute exposure to nerve agents such as soman(GD)causes serious brain damage,leading to death due to intense seizures induced by acetylcholinesterase inhibition and neuronal injury resulting from increased excitatory amino-acid levels and neuroinflammation.However,data on the anticonvulsant and neuroprotective efficacies of currently-used countermeasures are limited.Here,we evaluated the potential effects of transient receptor vanilloid 4(TRPV4)in the treatment of soman-induced status epilepticus(SE)and secondary brain injury.We demonstrated that TRPV4 expression was markedly up-regulated in rat hippocampus after soman-induced seizures.Administration of the TRPV4 antagonist GSK2193874 prior to soman exposure significantly decreased the mortality rate in rats and reduced SE intensity.TRPV4-knockout mice also showed lower incidence of seizures and higher survival rates than wild-type mice following soman exposure.Further in vivo and in vitro experiments demonstrated that blocking TRPV4 prevented NMDA receptor-mediated glutamate excitotoxicity.The protein levels of the NLRP3 inflammasome complex and its downstream cytokines IL-1βand IL-18 increased in soman-exposed rat hippocampus.However,TRPV4 inhibition or deletion markedly reversed the activation of the NLRP3 inflammasome pathway.In conclusion,our study suggests that the blockade of TRPV4 protects against soman exposure and reduces brain injury following SE by decreasing NMDA receptor-mediated excitotoxicity and NLRP3-mediated neuroinflammation.To our knowledge,this is the first study regarding the“dual-switch”function of TRPV4 in the treatment of soman intoxication.
基金supported by a NINDS Career Transition Award(to B.-S.C.).
文摘Glutamate-induced neuronal damage is mainly caused by overactivation of N-methyl-D-aspartate(NMDA)receptors.Conversely,normal physiological brain function and neuronal survival require adequate activation of NMDA receptors.Studies have revealed that NMDA receptor-induced neuronal death or survival is mediated through distinct subset of NMDA receptors triggering different intracellular signaling pathways.Here we discuss recent advances in the characterization of NMDA receptors in neuronal protection,emphasizing subunit-specific role,which contributes to temporal-spatial distribution,subcellular localization and diverse channel properties of NMDA receptors.
基金funded by the Fundamental Research Grant SchemeMinistry of Higher Education+2 种基金Malaysia (Grant No. FRGS/1/2018/SKK08/UITM/02/9)Geran Penyelidikan KhasUniversiti Teknologi MARA [Grant No. 600-RMC/GPK 5/3 (191/2020)]
文摘Memory impairment in children is an ongoing issue worldwide related to a learning disability. This neurobiological condition has been suggested to associate with bisphenol A (BPA) exposure during pregnancy. BPA is an inorganic compound used to produce polycarbonate plastics and epoxy resins. We conduct this study to investigate the effects of prenatal BPA exposure on the level of the N-methyl-D-aspartate (NMDA) receptor subunits, synaptic markers of the hippocampus and neurobehavioral outcomes in rats. The pregnant rats were given a daily dose of 5 mg/kg and 50 mg/kg of BPA with 0.5% Tween 80 orally from gestation day 2 until 21 (GD21). The level of GluN2A, GluN2B, PSD-95 and synapsin I in the hippocampus and its neurobehaviour outcomes were quantified and evaluated in the male foetus and adolescent rat. Prenatal BPA exposure reduced GluN2A, GluN2B, synapsin I and PSD-95 (Postsynaptic Density-95) in the male foetus and adolescent rat hippocampus compared to the control group. The prenatal BPA exposed rats demonstrated anxiety-related behaviour and impairment in aversive and spatial memory. The findings suggested that the impairment in neurobehavioral performance may inhibit the signalling pathway in the NMDA receptor subunits in the male foetus rat hippocampus leading to learning and memory deficits when reaching adolescence.
基金the National Nature Science Foundation of China(No.81373387)National Major Special Project on New Drug Innovation of China(No.2012ZX09301002-004)
文摘The rhizome of Gastrodia elata(GE), a herb medicine, has been used for treatment of neuronal disorders in Eastern Asia for hundreds of years. Parishin C is a major ingredient of GE. In this study, the i.c.v. injection of soluble Aβ1–42oligomers model of LTP injury was used. We investigated the effects of parishin C on the improvement of LTP in soluble Aβ1–42oligomer–injected rats and the underlying electrophysiological mechanisms. Parishin C(i.p. or i.c.v.) significantly ameliorated LTP impairment induced by i.c.v. injection of soluble Aβ1–42oligomers. In cultured hippocampal neurons,soluble Aβ1–42oligomers significantly inhibited NMDAR currents while not affecting AMPAR currents and voltage-dependent currents. Pretreatment with parishin C protected NMDA receptor currents from the damage induced by Aβ. In summary, parishin C improved LTP deficits induced by soluble Aβ1–42oligomers. The protection by parishin C against Aβ-induced LTP damage might be related to NMDA receptors.
基金supported by grants from the National Basic Research Program of China (2010CB912002)the National Natural Science Foundation of China (81221003 and 81271453)Fundamental Research Funds for the Central Universities of China
文摘N-methyl-D-aspartate receptors(NMDARs) containing different GluN2 subunits play distinct roles in synaptic plasticity.Such differences may not only be determined by the channel properties, but also by differential surface distribution and synaptic localization.In the present study, using a Cy3-conjugated Fab fragment of the GFP antibody to label surface-located GluN2 subunits tagged with GFP at the N-terminus, we observed the membrane distribution patterns of GluN2A- or GluN2B-containing NMDARs in cultured rat hippocampal neurons.We found that surface NMDARs containing GluN2 A, but not those containing GluN2 B, were inclined to cluster at DIV7.Swapping the carboxyl termini of the GluN2 subunits completely reversed these distribution patterns.In addition, surface NMDARs containing GluN2 A were preferentially associated with PSD-95.Taken together, the results of our study suggest that the clustering distribution of GluN2 Acontaining NMDARs is determined by the GluN2 A C-terminus, and its interaction with PSD-95 plays an important role in this process.
文摘Purpose To identify the structure and the function of NMDA receptors, to understand the modulatory mechanism of some endogenous and exogenous compounds on NMDA receptors, and to provide theoretical basis for developing new drugs that modulate NMDA receptors Data sources A total of 24 originally identified articles were selected Study selection A total of 24 articles were selected from several hundred original articles or reviews. The content of selected articles are in accordance with our purpose and the authors are authorized scientists in the study on NMDA receptors.Data extraction After careful review of the selected papers, the meaningful results and conclusions were extracted using scientific criteria and our experience in the research of NMDA receptors.Results NMDA receptor contains at least five subunits. They were designated as the NR1 (ζ1), NR2A (ε1), NR2B (ε2), NR2C (ε3), and NR2D (ε4). A unique feature of NMDA receptor is the requirement for both glutamate and the co agnist glycine for the efficient gating. NMDA receptor is modulated by a number of endogenous and exogenous compounds. Mg 2+ not only blocks the NMDA channel in a voltage dependent manner but also potentiates NMDA induced responses at positive membrane potentials. Na +, K + and Ca 2+ not only pass through the NMDA receptor channel but also modulate the activity of NMDA receptors. Zn 2+ blocks the NMDA current in a noncompetitive and a voltage independent manner. It has been demonstrated that polyamines do not directly activate NMDA receptors, but instead act to potentiate or inhibit glutamate mediated responses. The activity of NMDA receptors is also strikingly sensitive to the changes in H + concentration, and partially inhibited by the ambient concentration of H + under physiological conditions.Conclusions NMDA receptors are glutamate regulated by ion channels that are permeable to Ca 2+ , Na +, K + and are sensitive to voltage dependent Mg 2+ block This channel complex contributes to excitatory synaptic transmission at sites throughout the brain and the spinal cord,and is modulated by a number of endogenous and exogenous compounds NMDA receptors play a key role in wide range of physiologic and pathologic processes Five NMDA receptor subunits have now been characterized in both rat and mouse
基金supported by grants from the National Natural Science Foundation of China (81171042,81070893 and 81221002)the Beijing Outstanding Ph.D.Program Mentor Grantthe Specialized Research Fund for Doctoral Programs of Higher Education, China(20110001110058)
基金supported by grants from the National Natural Science Foundation of China (30900418)the Natural Science Program of Department of Education of Zhejiang Province,China (Y201122469)
文摘Activation of N-methyl-D-aspartate receptors(NMDARs)mediates changes in the phosphorylation status of the glutamate receptors themselves.Previous studies have indicated that during synaptic activity,tyrosine kinases(Src and Fyn)or phosphatases(PTPαand STEP)are involved in regulating the phosphorylation of NMDARs.In this study,we used immunoblotting to investigate the role of an NMDAR subpopulation on the phosphorylation level of the GluN2B subunit at the Y1336 and Y1472sites in rat brain slices after NMDA treatment.We found that NMDA stimulation dramatically decreased the phosphorylation level of GluN2B at Y1472 in a dose-and time-dependent manner,but not at Y1336.Extrasynaptic NMDAR activation did not reduce the phosphorylation of GluN2B at Y1472.In addition,ifenprodil,a selective antagonist of GluN2Bcontaining NMDARs,did not abolish the decreased phosphorylation of GluN2B at Y1472 triggered by NMDA.These results suggest that the activation of synaptic GluN2A-containing NMDARs is required for the decreased phosphorylation of GluN2B at Y1472that is induced by NMDA treatment in rat brain slices.
基金supported by grants from the National Natural Science Foundation of China(91232303,81221003,and 81561168)
文摘Accumulating evidence indicates that the synaptic activation of N-methyl-D-aspartate receptors(NMDARs) has a neuroprotective effect on neurons. Our previous study demonstrated that APPL1(adaptor protein containing pleckstrin homology domain, phosphotyrosinebinding domain, and leucine zipper motif) mediates the synaptic activity-dependent activation of PI3K-Akt signaling via coupling this pathway with NMDAR-PSD95(postsynaptic density protein 95) complexes. However, the molecular mechanism underlying this process is still unknown. In the present study, we investigated the interaction of APPL1 with PSD95 using co-immunocytochemical staining and western blotting. We found that the PDZ2 domain of PSD95 is a binding partner of APPL1.Furthermore, we identified serine 707 of APPL1, a predicted phosphorylation site within the PDZ-binding motif at the C-terminus, as critical for the binding of APPL1 to PSD95, as well as for activation of the Akt signaling pathway during synaptic activity. This suggests that serine707 of APPL1 is a potential phosphorylation site and may be involved in regulating the neuroprotective Akt signaling pathway that depends on synaptic NMDAR activity.
