Neuronal activity,synaptic transmission,and molecular changes in the basolateral amygdala play critical roles in fear memory.Cylindromatosis(CYLD)is a deubiquitinase that negatively regulates the nuclear factor kappa-...Neuronal activity,synaptic transmission,and molecular changes in the basolateral amygdala play critical roles in fear memory.Cylindromatosis(CYLD)is a deubiquitinase that negatively regulates the nuclear factor kappa-B pathway.CYLD is well studied in non-neuronal cells,yet underinvestigated in the brain,where it is highly expressed.Emerging studies have shown involvement of CYLD in the remodeling of glutamatergic synapses,neuroinflammation,fear memory,and anxiety-and autism-like behaviors.However,the precise role of CYLD in glutamatergic neurons is largely unknown.Here,we first proposed involvement of CYLD in cued fear expression.We next constructed transgenic model mice with specific deletion of Cyld from glutamatergic neurons.Our results show that glutamatergic CYLD deficiency exaggerated the expression of cued fear in only male mice.Further,loss of CYLD in glutamatergic neurons resulted in enhanced neuronal activation,impaired excitatory synaptic transmission,and altered levels of glutamate receptors accompanied by over-activation of microglia in the basolateral amygdala of male mice.Altogether,our study suggests a critical role of glutamatergic CYLD in maintaining normal neuronal,synaptic,and microglial activation.This may contribute,at least in part,to cued fear expression.展开更多
In addition to the loss of motor function,~60% of patients develop pain after spinal cord injury.The cellular-molecular mechanisms are not well understood,but the data suggests that plasticity within the rostral,epice...In addition to the loss of motor function,~60% of patients develop pain after spinal cord injury.The cellular-molecular mechanisms are not well understood,but the data suggests that plasticity within the rostral,epicenter,and caudal penumbra of the injury site initiates a cellularmolecular interplay that acts as a rewiring mechanism leading to central neuropathic pain.Sprouting can lead to the formation of new connections triggering abnormal sensory transmission.The excitatory glutamate transporters are responsible for the reuptake of extracellular glutamate which makes them a critical target to prevent neuronal hyperexcitability and excitotoxicity.Our previous studies showed a sexually dimorphic therapeutic window for spinal cord injury after treatment with the selective estrogen receptor modulator tamoxifen.In this study,we investigated the anti-allodynic effects of tamoxifen in male and female rats with spinal cord injury.We hypothesized that tamoxifen exerts anti-allodynic effects by increasing the expression of glutamate transporters,leading to reduced hyperexcitability of the secondary neuron or by decreasing aberrant sprouting.Male and female rats received a moderate contusion to the thoracic spinal cord followed by subcutaneous slow-release treatment of tamoxifen or matrix pellets as a control(placebo).We used von Frey monofilaments and the“up-down method”to evaluate mechanical allodynia.Tamoxifen treatment decreased allodynia only in female rats with spinal cord injury revealing a sexdependent effect.The expression profile of glutamatergic transporters(excitatory amino acid transporter 1/glutamate aspartate transporter and excitatory amino acid transporter 2/glutamate transporter-1)revealed a sexual dimorphism in the rostral,epicenter,and caudal areas of the spinal cord with a pattern of expression primarily on astrocytes.Female rodents showed a significantly higher level of excitatory amino acid transporter-1 expression while male rodents showed increased excitatory amino acid transporter-2 expression compared with female rodents.Analyses of peptidergic(calcitonin gene-related peptide-α)and non-peptidergic(isolectin B4)fibers outgrowth in the dorsal horn after spinal cord injury showed an increased calcitonin gene-related peptide-α/isolectin B4 ratio in comparison with sham,suggesting increased receptive fields in the dorsal horn.Although the behavioral assay shows decreased allodynia in tamoxifen-treated female rats,this was not associated with overexpression of glutamate transporters or alterations in the dorsal horn laminae fibers at 28 days post-injury.Our findings provide new evidence of the sexually dimorphic expression of glutamate transporters in the spinal cord.The dimorphic expression revealed in this study provides a therapeutic opportunity for treating chronic pain,an area with a critical need for treatment.展开更多
In this paper,the effect of sodium laurate(SL)on the properties of sodium lauroyl glutamate(SLG),such as surface activity,foam,wetting,emulsification,and resistance to hard water,has been systematically investigated.T...In this paper,the effect of sodium laurate(SL)on the properties of sodium lauroyl glutamate(SLG),such as surface activity,foam,wetting,emulsification,and resistance to hard water,has been systematically investigated.The results showed that the critical micelle concentration(cmc)of SLG was 0.30 mmol/L,and the surface tension at the cmc(γcmc)was 34.95 mN/m.With the increase of SL content,the efficiency of SLG solution in reducing the surface tension was decreased.When the SL content was increased,there was no significant change in the foaming ability and foam stability of SLG solutions.The increase of SL content improved both the emulsification and wettability of SLG,but reduced its water resistance.展开更多
In this study,we systematically tested the hypothesis that during the critical developmental period of adolescence,on a macro scale,the concentrations of major excitatory and inhibitory neurotransmitters(glutamate/glu...In this study,we systematically tested the hypothesis that during the critical developmental period of adolescence,on a macro scale,the concentrations of major excitatory and inhibitory neurotransmitters(glutamate/glutamine andγ‑aminobutyric acid[GABA])in the dorsal and ventral lateral prefrontal cortex are associated with the brain’s functional connectivity and an individual’s psychopathology.Neurotransmitters were measured via magnetic resonance spectroscopy while functional connectivity was measured with resting-state fMRI(n=121).Seed-based and network-based analyses revealed associations of neurotransmitter concentrations and functional connectivities between regions/networks that are connected to prefrontal cortices via structural connections that are thought to be under dynamic development during adolescence.These regions tend to be boundary areas between functional networks.Furthermore,several connectivities were found to be associated with individual’s levels of internalizing psychopathology.These findings provide insights into specific neurochemical mechanisms underlying the brain’s macroscale functional organization,its development during adolescence,and its potential associations with symptoms associated with internalizing psychopathology.展开更多
BACKGROUND The global prevalence of metabolic dysfunction-associated steatotic liver disease(MASLD)has continued to increase annually.Recent studies have indicated that inhibition of metabotropic glutamate receptor 5(...BACKGROUND The global prevalence of metabolic dysfunction-associated steatotic liver disease(MASLD)has continued to increase annually.Recent studies have indicated that inhibition of metabotropic glutamate receptor 5(mGluR5)may alleviate hepatic steatosis.However,the precise mechanism warrants further exploration.AIM To investigate the potential mechanism by which mGluR5 attenuates hepatocyte steatosis in vitro and in vivo.METHODS Free fatty acids(FFAs)-stimulated HepG2 cells were treated with the mGluR5 antagonist MPEP and the mGluR5 agonist CHPG.Oil Red O staining and a triglyceride assay kit were used to evaluate lipid content.Western blot analysis was conducted to detect the expression of the autophagy-associated proteins p62 and LC3-II,as well as the expression of the key signaling molecules AMPK and ULK1,in the treated cells.To further elucidate the contributions of autophagy and AMPK,we used chloroquine(CQ)to inhibit autophagy and compound C(CC)to inhibit AMPK activity.In parallel,wild-type mice and mGluR5 knockout(KO)mice fed a normal chow diet or a high-fat diet(HFD)were used to evaluate the effect of mGluR5 inhibition in vivo.RESULTS mGluR5 inhibition by MPEP attenuated hepatocellular steatosis and increased LC3-II and p62 protein expression.The autophagy inhibitor CQ reversed the effects of MPEP.In addition,MPEP promoted AMPK and ULK1 expression in HepG2 cells exposed to FFAs.MPEP treatment led to the nuclear translocation of transcription factor EB,which is known to promote p62 expression.This effect was negated by the AMPK inhibitor CC.mGluR5 KO mice presented reduced body weight,improved glucose tolerance and reduced hyperlipidemia when fed a HFD.Additionally,the livers of HFD-fed mGluR5 KO mice presented increases in LC3-II and p62.CONCLUSION Our results suggest that mGluR5 inhibition promoted autophagy and reduced hepatocyte steatosis through activation of the AMPK signaling pathway.These findings reveal a new functional mechanism of mGluR5 as a target in the treatment of MASLD.展开更多
Glutamate is an essential excitatory neurotransmitter in the brain,playing a vital role in regulating synaptic activity and maintaining the homeostasis of the cerebral environment but also serves as a central hub for ...Glutamate is an essential excitatory neurotransmitter in the brain,playing a vital role in regulating synaptic activity and maintaining the homeostasis of the cerebral environment but also serves as a central hub for neuronal injury and inflammatory responses.In various pathological conditions,such as ischemic stroke,glutamate is released and accumulates excessively in the brain,leading to heightened stimulation of neurons and excitotoxicity.This phenomenon positions glutamate as a primary inducing factor for neuronal damage following cerebral ischemia.Glutamate exerts its effects primarily through two types of receptors:ionotropic andmetabotropic glutamate receptors,both of which are extensively distributed throughout the hippocampus and cortical regions of the brain.Ionotropic receptors mediate rapid excitatory neurotransmission upon activation by glutamate;these are mainly categorized into N-methyl-D-aspartate receptors(NMDARs),α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid receptors(AMPARs),and kainate receptors(KARs).Conversely,metabotropic receptors function asG-protein-coupled receptors(GPCR)facilitating glutamatergic cellular effects via intracellular secondmessenger.With the comprehensive investigation of glutamate receptors and their structural characteristics,our understanding of the nerve damage and protective mechanisms associated with glutamate receptors in ischemic stroke is progressively advancing.Consequently,exploring the role of glutamate receptors and their downstream signaling pathways in cerebral ischemia can provide a robust theoretical foundation for targeted therapies aimed at treating cerebral ischemia,stroke,and related disorders.This article reviews the function of glutamate receptors and theirmediated downstreamsignal transduction pathways in the context of ischemic brain injury.展开更多
Glutamine and glutamate are major bioenergy substrates for normal and cancer cell growth.Cancer cells need more biofuel than normal tissues for energy supply,anti-oxidation activity and biomass production.Genes relate...Glutamine and glutamate are major bioenergy substrates for normal and cancer cell growth.Cancer cells need more biofuel than normal tissues for energy supply,anti-oxidation activity and biomass production.Genes related to metabolic chains in many cancers are somehow mutated,which makes cancer cells more glutamate dependent.Meanwhile,glutamate is an excitatory neurotransmitter for conducting signals through binding with different types of receptors in central neuron system.Interestingly,increasing evidences have shown involvement of glutamate signaling,guided through their receptors,in human malignancy.Dysregulation of glutamate transporters,such as excitatory amino acid transporter and cystine/glutamate antiporter system,also generates excessive extracellular glutamate,which in turn,activates glutamate receptors on cancer cells and results in malignant growth.These features make glutamate an attractive target for anti-cancer drug development with some glutamate targeted but blood brain barrier impermeable anti-psychosis drugs under consideration.We discussed the relevant progressions and drawbacks in this field herein.展开更多
The present study established a rat model of global cerebral ischemia induced by chest compression for six minutes to dynamically observe expressional changes of three glutamate transporters in the cerebral cortex and...The present study established a rat model of global cerebral ischemia induced by chest compression for six minutes to dynamically observe expressional changes of three glutamate transporters in the cerebral cortex and hippocampus. After 24 hours of ischemia, expression of glutamate transporter-1 significantly decreased in the cerebral cortex and hippocampus, which was accompanied by neuronal necrosis. At 7 days post-ischemia, expression of excitatory amino acid carrier 1 decreased in the hippocampal CA1 region and cortex, and was accompanied by apoptosis Expression of glutamate-aspartate transporter remained unchanged at 6 hours 7 days after ischemia. These results suggested that glutamate transporter levels were altered at different periods of cerebral ischemia.展开更多
Objective To investigate whether environmental cues associated with different properties of morphine could regulate the extracellular levels of glutamate and y-aminobutyric acid （GABA） in the hippocampal ventral sub...Objective To investigate whether environmental cues associated with different properties of morphine could regulate the extracellular levels of glutamate and y-aminobutyric acid （GABA） in the hippocampal ventral subiculum, which play a critical role in the reinstatement of drug-seeking behavior induced by environmental cues. Methods Conditioning place preference （CPP） and conditioning place aversion （CPA） models were used to establish environment associated with rewarding and aversive properties of morphine respectively. Microdialysis and high performance liquid chromatography were used to measure the extracelluar level of glutamate and GABA in the ventral subiculum under these environmental cues. Results Exposure to the environmental cues associated with rewarding properties of morphine resulted in a decrease （approximately 11%） of extracellular level of GABA in ventral subiculum, and exposure to the environmental cues associated with aversive properties of morphine resulted in an increase （approximately 230%） of extracellular level of glutamate in ventral subiculum. Conclusion Environmental cues associated with different properties of morphine modulate the release of distinct neurotransmitters in the hippocampal ventral subiculum possibly through different neural circuit.展开更多
A full_length cDNA has been cloned encoding nicotinamide adenine dinucleotide phosphate_specific glutamate dehydrogenase (NADP_GDH) from Chlorella sorokiniana with the RT_PCR method. The complete nucleotide sequence o...A full_length cDNA has been cloned encoding nicotinamide adenine dinucleotide phosphate_specific glutamate dehydrogenase (NADP_GDH) from Chlorella sorokiniana with the RT_PCR method. The complete nucleotide sequence of NADP_GDH gene had 94% homology to the previously reported one . The NADP_GDH gene was constructed into a vector highly expressed in plants. The specific activity of NADP_GDH in transformants was detected, but not in the control plants. All transformed shoots on MS medium containing lower concentration of nitrogen and the transformed seedlings grown in lower concentration of nitrogen vermiculite had higher growth rate and more leaves than the control plants. Transformed leaf discs cultured on MS medium containing different nitrogen concentrations had more chlorophyll contents compared to the controls. These results suggested that exogenous NADP_GDH may enhance the absorption and utilization to ammonium in plants. The increased weight of transformed leaf discs cultured on medium supplemented with different concentrations of phosphinothricin (PPT) was more than that of control discs. 0.5 μg/mL PPT could be used as a selecting drug instead of kanamycin to develop the transformants. These results suggested that the NADP_GDH gene might be used as a new selecting gene in the future research of plant gene engineering.展开更多
Maintaining glutamate homeostasis after hypoxic ischemia is important for synaptic function and neural cell activity,and regulation of glutamate transport between astrocyte and neuron is one of the important modalitie...Maintaining glutamate homeostasis after hypoxic ischemia is important for synaptic function and neural cell activity,and regulation of glutamate transport between astrocyte and neuron is one of the important modalities for reducing glutamate accumulation.However,further research is needed to investigate the dynamic changes in and molecular mechanisms of glutamate transport and the effects of glutamate transport on synapses.The aim of this study was to investigate the regulatory mechanisms underlying Notch pathway mediation of glutamate transport and synaptic plasticity.In this study,Yorkshire neonatal pigs(male,age 3 days,weight 1.0–1.5 kg,n=48)were randomly divided into control(sham surgery group)and five hypoxic ischemia subgroups,according to different recovery time,which were then further subdivided into subgroups treated with dimethyl sulfoxide or a Notch pathway inhibitor(N-[N-(3,5-difluorophenacetyl-l-alanyl)]-S-phenylglycine t-butyl ester).Once the model was established,immunohistochemistry,immunofluorescence staining,and western blot analyses of Notch pathway-related proteins,synaptophysin,and glutamate transporter were performed.Moreover,synapse microstructure was observed by transmission electron microscopy.At the early stage(6–12 hours after hypoxic ischemia)of hypoxic ischemic injury,expression of glutamate transporter excitatory amino acid transporter-2 and synaptophysin was downregulated,the number of synaptic vesicles was reduced,and synaptic swelling was observed;at 12–24 hours after hypoxic ischemia,the Notch pathway was activated,excitatory amino acid transporter-2 and synaptophysin expression was increased,and the number of synaptic vesicles was slightly increased.Excitatory amino acid transporter-2 and synaptophysin expression decreased after treatment with the Notch pathway inhibitor.This suggests that glutamate transport in astrocytes-neurons after hypoxic ischemic injury is regulated by the Notch pathway and affects vesicle release and synaptic plasticity through the expression of synaptophysin.展开更多
Glutamate is the predominant excitatory neurotransmitter in the human brain and it has been shown that prolonged activation of the glutamatergic system leads to nerve damage and cell death.Following release from the p...Glutamate is the predominant excitatory neurotransmitter in the human brain and it has been shown that prolonged activation of the glutamatergic system leads to nerve damage and cell death.Following release from the pre-synaptic neuron and synaptic transmission,glutamate is either taken up into the presynaptic neuron or neighbouring glia by transmembrane glutamate transporters.Excitatory amino acid transporter(EAAT)1 and EAAT2 are Na+-dependant glutamate transporters expressed predominantly in glia cells of the central nervous system.As the most abundant glutamate transporters,their primary role is to modulate levels of glutamatergic excitability and prevent spill over of glutamate beyond the synapse.This role is facilitated through the binding and transportation of glutamate into astrocytes and microglia.The function of EAAT1 and EAAT2 is heavily regulated at the levels of gene expression,post-transcriptional splicing,glycosylation states and cell-surface trafficking of the protein.Both glutamatergic dysfunction and glial dysfunction have been proposed to be involved in psychiatric disorder.This review will present an overview of the roles that EAAT1 and EAAT2 play in modulating glutamatergic activity in the human brain,and mount an argument that these two transporters could be involved in the aetiologies of schizophrenia and affective disorders as well as represent potential drug targets for novel therapies for those disorders.展开更多
OBJECTIVE: To investigate the antiepileptic effects of Chaihushugan decoction(CHSGD) in rats with pentylenetetrazole(PTZ)-induced seizures and to discuss the impact of CHSGD on glutamate metabolism, a hypothesized und...OBJECTIVE: To investigate the antiepileptic effects of Chaihushugan decoction(CHSGD) in rats with pentylenetetrazole(PTZ)-induced seizures and to discuss the impact of CHSGD on glutamate metabolism, a hypothesized underlying mechanism of seizure reduction.METHODS: Fifty Wistar rats were divided randomly into either control(n = 10) or experimental(n = 40)groups. Rats in the control group were administered physiological saline intraperitoneally. A subconvulsive dose of PTZ(35 mg/kg) was administered intraperitoneally to rats in the experimental group to induce seizures. The fully PTZ-kindled rats were then randomly divided into five subgroups(n = 8 each) based on the following treatment categories: physiological saline, VPA(200 mg/kg), CHSGD(2.5 g/kg), CHSGD(5 g/kg), or CHSGD(10 g/kg),administered orally once per day, respectively. On day 28 following initiation of drug treatment, seizures were monitored. The rats were then sacrificed, and hippocampal dissections were performed for subsequent studies.RESULTS: CHSGD significantly prolonged the latency of myoclonic, clonic, and tonic seizures, while decreasing overall seizure rates in the kindled rats.The measured concentrations of 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl) amino]-2-deoxy-d-glucose(2-NBDG) and glutamate were significantly lower in the hippocampi of kindled rats in groups treated with CHSGD compared with those treated with PTZ alone. In addition, CHSGD was found to up-regulate both the expression of glutamate transporter-1(GLT-1) protein and the activity of glutamine synthetase(GS) in the hippocampi of kindled rats.CONCLUSION: These results suggest that CHSGD has antiepileptic effects on PTZ-induced seizures.The results further suggest an increase in glutamate metabolism at the synaptic cleft is a putative underlying mechanism of seizure reduction.展开更多
Glutamate is the major excitatory neurotransmitter in the mammalian central nervous system (CNS). Packaging and storage of glutamate into glutamatergic neuronal vesicles require ATP-dependent vesicular glutamate uptak...Glutamate is the major excitatory neurotransmitter in the mammalian central nervous system (CNS). Packaging and storage of glutamate into glutamatergic neuronal vesicles require ATP-dependent vesicular glutamate uptake systems, which utilize the electrochemical proton gradient as a driving force. Three vesicular glutamate transporters (VGLUT1-3) have been recently identified from neuronal tissue where they play a key role to maintain the vesicular glutamate level. Recently, it has been demonstrated that glutamate signaling is also functional in peripheral neuronal and non-neuronal tissues, and occurs in sites of pituitary, adrenal, pineal glands, bone, GI tract, pancreas,skin, and testis. The glutamate receptors and VGLUTs in digestivesystem have been found in both neuronal and endocrinal cells. The glutamate signaling in the digestive system may have significant relevance to diabetes and GI tract motility disorders. This review will focus on the most recent update of molecular physiology of digestive VGLUTs.展开更多
BACKGROUND： Injection of glutamate （Glu） in normal animals can cause neuronal c-Fos expression; however, whether Glu can induce spinal neuronal c-Fos expression in pain models is unclear. OBJECTIVE： To examine the...BACKGROUND： Injection of glutamate （Glu） in normal animals can cause neuronal c-Fos expression; however, whether Glu can induce spinal neuronal c-Fos expression in pain models is unclear. OBJECTIVE： To examine the effects of intraplantar and intrathecal injection of Glu on c-Fos expression in the L5 spinal cord dorsal horn Ⅰ/Ⅱ and Ⅲ/Ⅳ layers after spinal nerve ligation, and to study the effects of the N-methyI-D-aspartic acid （NMDA） receptor antagonist, D-2-amino-5-phosphonopentanoate （D-AP5）, and a selective group I mGluR antagonist, 7-hydroyiminocyclo propan[a]chromen-lacarboxylic acid ethyl ester （cpccoEt）. DESIGN, TIME AND SETTING： A randomized, controlled animal study was performed at the Department of Pharmacology, Oral Anatomy, and Neurobiology, Osaka University Graduate School of Dentistry, from December 2005 to December 2006. MATERIALS： Glu （5 μmol）, D-AP5 （50 nmot） and cpccoEt （250 nmol） were provided by Wako Pure Chemical Industries, Osaka, Japan, and diluted in saline （50 μL）. The pH of all solutions was adjusted to 7.4. METHODS： Twelve rats were randomly divided into sham operation （n = 6） and spinal nerve ligation （SNL; n = 6） groups for behavioral assessments of neuropathic pain after ligation surgery of the left L5-6 nerve segment. Another 60 rats were randomly divided into sham operation, SNL, saline-intraplantar, saline-intrathecal, Glu-intraplantar, Glu-intrathecal, D-AP5-intrathecal, Glu-D-AP5-intrathecal, cpccoEt-intrathecal, and Glu-cpccoEt-intrathecal groups, with 6 rats in each group. All groups except sham operation group received a similar SNL. On day 14, rats received a 50-μL injection of saline, Glu, D-AP5, and/or cpccoEt into the left intraplantar or intrathecal L5-4 segments. MAIN OUTCOME MEASURES： The number of c-Fos positive neurons in both Ⅰ/Ⅱ and Ⅲ/Ⅳ spinal layers at L6 was observed using immunohistochemistry 2 hours after administration. RESULTS： （1） SNL increased the level of c-Fos expression in two sides of the spinal cord, particularly on Ⅲ/Ⅳ spinal layers of the ligated side. （2） Intraplantar or intrathecal administration of saline significantly increased the c-Fos labeled neurons in Ⅰ/Ⅱ spinal layers of the ligated side, compared with SNL alone （P 〈 0.01）. （3） Intraplantar Glu （5 μmol） increased the number of c-Fos positive neurons in Ⅰ/Ⅱ spinal layers compared with intraplantar saline （P〈 0.01）. （4） The number of c-Fos neurons in Ⅰ/Ⅱ spinal layers on both the ipsilateral and contralateral side after intraplantar Glu was lower than intrathecal Glu （P〈 0.01）, with a 3-fold higher induction by intrathecal Glu. （5） Co-administration of D-AP5 or cpccoEt reduced the effects of intrathecal Glu （P 〈 0.01）. CONCLUSION： Intrathecal Glu increases c-Fos expression more than intraplantar Glu. Antagonists of NMDA and group I mGluRs block this effect.展开更多
Patients with liver disease may present hepatic enceph- alopathy (HE), a complex neuropsychiatric syndrome covering a wide range of neurological alterations, including cognitive and motor disturbances. HE reduces the ...Patients with liver disease may present hepatic enceph- alopathy (HE), a complex neuropsychiatric syndrome covering a wide range of neurological alterations, including cognitive and motor disturbances. HE reduces the quality of life of the patients and is associated with poor prognosis. In the worse cases HE may lead to coma or death. The mechanisms leading to HE which are not well known are being studied using animal models. The neurological alterations in HE are a consequence of impaired cerebral function mainly due to alterations in neurotransmission. We review here some studies indicating that alterations in neurotransmission associated to different types of glutamate receptors are responsible for some of the cognitive and motor alterations present in HE. These studies show that the function of the signal transduction pathway glutamate-nitric oxide-cGMP associated to the NMDA type of glutamate receptors is impaired in brain in vivo in HE animal models as well as in brain of patients died of HE. Activation of NMDA receptors in brain activates this pathway and increases cGMP. In animal models of HE this increase in cGMP induced by activation of NMDA receptors is reduced, which is responsible for the impairment in learning ability in these animal models. Increasing cGMP by pharmacological means restores learning ability in rats with HE and may be a new therapeutic approach to improve cognitive function in patients with HE. However, it is necessary to previously assess the possible secondary effects.Patients with HE may present psychomotor slowing, hypokinesia and bradykinesia. Animal models of HE also show hypolocomotion. It has been shown in rats with HE that hypolocomotion is due to excessive activation of metabotropic glutamate receptors (mGluRs) in substantia nigra pars reticulata. Blocking mGluR1 in this brain area normalizes motor activity in the rats, suggesting that a similar treatment for patients with HE could be useful to treat psychomotor slowing and hypokinesia. However, the possible secondary effects of mGluR1 antagonists should be previously evaluated. These studies are setting the basis for designing therapeutic procedures to specifically treat the individual neurological alterations in patients with HE.展开更多
BACKGROUND：Studies have reported that potassium channel openers exhibit a protective effect on cerebral ischemia-reperfusion injury and inhibit glutamate excitotoxicity in rats.However,the effects of the glutamate re...BACKGROUND：Studies have reported that potassium channel openers exhibit a protective effect on cerebral ischemia-reperfusion injury and inhibit glutamate excitotoxicity in rats.However,the effects of the glutamate receptor 1α and glutamate transporter 1 remain poorly understood.OBJECTIVE：To investigate the prophylactic use of the adenosine triphosphate-sensitive potassium channel opener cromakalim on neurological function and cerebral infarct size,as well as glutamate receptor 1α and glutamate transporter 1 expression,in rats with cerebral ischemia-reperfusion injury,and to explore action mechanisms underlying reduced glutamate excitotoxicity and neuroprotection in rats.DESIGN,TIME AND SETTING：Randomized,controlled,animal experiment was performed at the Brain Institute,Qingdao University Medical College,Between July 2008 and April 2009.MATERIALS：Cromakalim was purchased from Sigma,USA; rabbit anti-glutamate receptor 1α polyclonal antibody was offered by Wuhan Boster,China; rabbit anti-glutamate transporter 1 polyclonal antibody was offered by Santa Cruz Biotechnology,USA.METHODS：Sixty male,Wistar rats,aged 6 months,were randomly assigned to three groups （n =20）：sham-surgery,model,and cromakalim.Intraluminal thread methods were used to establish middle cerebral artery occlusion in rats from the model and cromakalim groups.Rats from the sham-surgery group were subjected to exposed common carotid artery,external carotid artery,and internal carotid artery,without occlusion.Cromakalim （10 mg/kg） was administered 30 minutes prior to middle cerebral artery occlusion,but there was no intervention in the model and sham-surgery groups.MAIN OUTCOME MEASURES：At 24 hours post-surgery,neurological behavioral functions were evaluated using Bederson＇s test,cerebral infarction volume was determined following tetrazolium chloride staining,and glutamate receptor 1a and glutamate transporter 1 expressions were detected using immunohistochemistry.RESULTS：Following cerebral ischemia-reperfusion injury,neurological behavioral malfunctions were obvious in all mice.Focal cerebral infarction was detected in ischemic hemispheres,glutamate receptor 1α expression increased,and glutamate transporter 1 expression decreased in the ischemic hemisphere （P〈 0.05）.Compared with the model group,neurological behavioral functions significantly improved,cerebral infarction volume was significantly reduced （P〈 0.05）,glutamate receptor 1α expression was significantly decreased,and glutamate transporter 1 expression was increased in the cromakalim group （P 〈 0.05）.CONCLUSION：Improved neurological function and reduced cerebral infarction volume in rats through the preventive use of cromakalim could be related to decreased glutamate receptor 1α expression and enhanced glutamate transporter 1 expression.展开更多
In recent years, more attention has been paid to the role of the glutamate transporter 1 （GLT-1, EAAT2） in major depressive disorder （MDD）. However, experimental data on brain GLT-1 levels are, to some extent, inc...In recent years, more attention has been paid to the role of the glutamate transporter 1 （GLT-1, EAAT2） in major depressive disorder （MDD）. However, experimental data on brain GLT-1 levels are, to some extent, inconsistent in human postmortem and animal studies, These discrepancies imply that the role of GLT-1 in the pathophysiology of MDD and the action of antidepressants remain obscure. This work was designed to study the impact of chronic unpredictable stress （CUS） for 2 ses- sions per day for 35 days and four weeks of fluoxetine （FLX） on depressive-like behaviors in rats, as well as the concomitant expression of the GLT-1 protein in the hippocampus. Behavioral changes were assessed by the sucrose preference and open field tests. GLT-1 levels were detected by immunohisto- chemistry and Western blot analysis. Our study demonstrated that the animals exposed to CUS showed depressive-like behaviors and exhibited a significant decrease in GLT-1 expression in the hippocampus. Chronic FLX treatment reversed the behavioral deficits and the CUS-induced decrease in GLT-1 levels. Taken together, our results support the reduction of GLT-1 in human postmortem studies in MDD and suggest that GLT-1 may be involved in the antidepressant activity of FLX. Our studies further support the notion that GLT-1 is an attractive candidate molecule associated with the fundamental processes of MDD and may be a potential, and novel pharmacological target for the treatment of MDD.展开更多
Glutamate is a regulated molecule in the mammalian testis. Extracellular regulation of glutamate in the body is determined largely by the expression of plasmalemmal glutamate transporters. We have examined by PCR, wes...Glutamate is a regulated molecule in the mammalian testis. Extracellular regulation of glutamate in the body is determined largely by the expression of plasmalemmal glutamate transporters. We have examined by PCR, western blotting and immunocytochemistry the expression of a panel of sodium-dependent plasmalemmal glutamate transporters in the rat testis. Proteins examined included： glutamate aspartate transporter （GLAST）, glutamate transporter 1 （GLT1）, excitatory amino acid carrier 1 （EAAC1）, excitatory amino acid transporter 4 （EAAT4） and EAAT5. We demonstrate that many of the glutamate transporters in the testis are alternately spliced. GLAST is present as exon-3- and exon-9-skipping forms. GLT1 was similarly present as the alternately spliced forms GLT1 b and GLTlc, whereas the abundant brain form （GLTla） was detectable only at the mRNA level. EAAT5 was also strongly expressed, whereas EAAC1 and EAAT4 were absent. These patterns of expression were compared with the patterns of endogenous glutamate localization and with patterns of D-aspartate accumulation, as assessed by immunocytochemistry. The presence of multiple glutamate transporters in the testis, including unusually spliced forms, suggests that glutamate homeostasis may be critical in this organ. The apparent presence of many of these transporters in the testis and sperm may indicate a need for glutamate transport by such cells.展开更多
Activation of presynaptic group II metabotropic glutamate receptors（mGluR2/3） inhibits drug reward and drug-seeking behavior, but the role of N-acetylaspartylglutamate（NAAG）, an agonist of endogenous mGluR2/3,in h...Activation of presynaptic group II metabotropic glutamate receptors（mGluR2/3） inhibits drug reward and drug-seeking behavior, but the role of N-acetylaspartylglutamate（NAAG）, an agonist of endogenous mGluR2/3,in heroin reward and heroin-seeking behavior remained unclear. Here, we aimed to explore the effects of exogenous NAAG on heroin self-administration and heroinseeking behavior. First, rats were trained to self-administer heroin under a fixed ratio 1（FR1） schedule for 10 days,then received NAAG（50 or 100μg/10 μL in each nostril）in the absence or presence of LY341495（1 mg/kg, i.p.）, an antagonist of mGluR2/3, on day 11 and the effects of NAAG on heroin self-administration under FR1 were recorded for 3 consecutive days. Motivation was assessed in heroin self-administration under a progressive ratio schedule on day 11 in another 5 groups with the same doses of NAAG. Additional rats were withdrawn for 14 days after 14 days of heroin self-administration, then received the same pharmacological pretreatment and were tested for heroin-seeking behaviors induced by heroin priming or cues. The results showed that intranasal administration of NAAG significantly decreased intravenous heroin selfadministration on day 12, but not on day 11. Pretreatment with LY341495 prior to testing on day 12 prevented the inhibitory effect of NAAG on heroin reinforcement. The break-point for reward motivation was significantly reduced by NAAG. Moreover, NAAG also significantly inhibited the heroin-seeking behaviors induced by heroinpriming or cues and these were restored by pretreatment with LY341495. These results demonstrated that NAAG,via activation of presynaptic mGluR2/3, attenuated the heroin reinforcement, heroin motivational value, and heroin-seeking behavior, suggesting that it may be used as an adjunct treatment for heroin addiction.展开更多
基金supported by the National Natural Science Foundation of China,Nos.32371065(to CL)and 32170950(to LY)the Natural Science Foundation of the Guangdong Province,No.2023A1515010899(to CL)the Science and Technology Projects in Guangzhou,Nos.2023A4J0578 and 2024A03J0180(to CW)。
文摘Neuronal activity,synaptic transmission,and molecular changes in the basolateral amygdala play critical roles in fear memory.Cylindromatosis(CYLD)is a deubiquitinase that negatively regulates the nuclear factor kappa-B pathway.CYLD is well studied in non-neuronal cells,yet underinvestigated in the brain,where it is highly expressed.Emerging studies have shown involvement of CYLD in the remodeling of glutamatergic synapses,neuroinflammation,fear memory,and anxiety-and autism-like behaviors.However,the precise role of CYLD in glutamatergic neurons is largely unknown.Here,we first proposed involvement of CYLD in cued fear expression.We next constructed transgenic model mice with specific deletion of Cyld from glutamatergic neurons.Our results show that glutamatergic CYLD deficiency exaggerated the expression of cued fear in only male mice.Further,loss of CYLD in glutamatergic neurons resulted in enhanced neuronal activation,impaired excitatory synaptic transmission,and altered levels of glutamate receptors accompanied by over-activation of microglia in the basolateral amygdala of male mice.Altogether,our study suggests a critical role of glutamatergic CYLD in maintaining normal neuronal,synaptic,and microglial activation.This may contribute,at least in part,to cued fear expression.
基金supported by COBRE(P30GM149367)the Puerto Rico Science&Technology Trust(2022-00125)+1 种基金MBRS-RISE Program(R25 GM061838)SC1GM144032 program(all to JDM)。
文摘In addition to the loss of motor function,~60% of patients develop pain after spinal cord injury.The cellular-molecular mechanisms are not well understood,but the data suggests that plasticity within the rostral,epicenter,and caudal penumbra of the injury site initiates a cellularmolecular interplay that acts as a rewiring mechanism leading to central neuropathic pain.Sprouting can lead to the formation of new connections triggering abnormal sensory transmission.The excitatory glutamate transporters are responsible for the reuptake of extracellular glutamate which makes them a critical target to prevent neuronal hyperexcitability and excitotoxicity.Our previous studies showed a sexually dimorphic therapeutic window for spinal cord injury after treatment with the selective estrogen receptor modulator tamoxifen.In this study,we investigated the anti-allodynic effects of tamoxifen in male and female rats with spinal cord injury.We hypothesized that tamoxifen exerts anti-allodynic effects by increasing the expression of glutamate transporters,leading to reduced hyperexcitability of the secondary neuron or by decreasing aberrant sprouting.Male and female rats received a moderate contusion to the thoracic spinal cord followed by subcutaneous slow-release treatment of tamoxifen or matrix pellets as a control(placebo).We used von Frey monofilaments and the“up-down method”to evaluate mechanical allodynia.Tamoxifen treatment decreased allodynia only in female rats with spinal cord injury revealing a sexdependent effect.The expression profile of glutamatergic transporters(excitatory amino acid transporter 1/glutamate aspartate transporter and excitatory amino acid transporter 2/glutamate transporter-1)revealed a sexual dimorphism in the rostral,epicenter,and caudal areas of the spinal cord with a pattern of expression primarily on astrocytes.Female rodents showed a significantly higher level of excitatory amino acid transporter-1 expression while male rodents showed increased excitatory amino acid transporter-2 expression compared with female rodents.Analyses of peptidergic(calcitonin gene-related peptide-α)and non-peptidergic(isolectin B4)fibers outgrowth in the dorsal horn after spinal cord injury showed an increased calcitonin gene-related peptide-α/isolectin B4 ratio in comparison with sham,suggesting increased receptive fields in the dorsal horn.Although the behavioral assay shows decreased allodynia in tamoxifen-treated female rats,this was not associated with overexpression of glutamate transporters or alterations in the dorsal horn laminae fibers at 28 days post-injury.Our findings provide new evidence of the sexually dimorphic expression of glutamate transporters in the spinal cord.The dimorphic expression revealed in this study provides a therapeutic opportunity for treating chronic pain,an area with a critical need for treatment.
文摘In this paper,the effect of sodium laurate(SL)on the properties of sodium lauroyl glutamate(SLG),such as surface activity,foam,wetting,emulsification,and resistance to hard water,has been systematically investigated.The results showed that the critical micelle concentration(cmc)of SLG was 0.30 mmol/L,and the surface tension at the cmc(γcmc)was 34.95 mN/m.With the increase of SL content,the efficiency of SLG solution in reducing the surface tension was decreased.When the SL content was increased,there was no significant change in the foaming ability and foam stability of SLG solutions.The increase of SL content improved both the emulsification and wettability of SLG,but reduced its water resistance.
基金supported by NIMH grant R01105501(PI:MTB and BLK).
文摘In this study,we systematically tested the hypothesis that during the critical developmental period of adolescence,on a macro scale,the concentrations of major excitatory and inhibitory neurotransmitters(glutamate/glutamine andγ‑aminobutyric acid[GABA])in the dorsal and ventral lateral prefrontal cortex are associated with the brain’s functional connectivity and an individual’s psychopathology.Neurotransmitters were measured via magnetic resonance spectroscopy while functional connectivity was measured with resting-state fMRI(n=121).Seed-based and network-based analyses revealed associations of neurotransmitter concentrations and functional connectivities between regions/networks that are connected to prefrontal cortices via structural connections that are thought to be under dynamic development during adolescence.These regions tend to be boundary areas between functional networks.Furthermore,several connectivities were found to be associated with individual’s levels of internalizing psychopathology.These findings provide insights into specific neurochemical mechanisms underlying the brain’s macroscale functional organization,its development during adolescence,and its potential associations with symptoms associated with internalizing psychopathology.
基金Supported by National Natural Science Foundation of China,No.81800771 and No.81300702.
文摘BACKGROUND The global prevalence of metabolic dysfunction-associated steatotic liver disease(MASLD)has continued to increase annually.Recent studies have indicated that inhibition of metabotropic glutamate receptor 5(mGluR5)may alleviate hepatic steatosis.However,the precise mechanism warrants further exploration.AIM To investigate the potential mechanism by which mGluR5 attenuates hepatocyte steatosis in vitro and in vivo.METHODS Free fatty acids(FFAs)-stimulated HepG2 cells were treated with the mGluR5 antagonist MPEP and the mGluR5 agonist CHPG.Oil Red O staining and a triglyceride assay kit were used to evaluate lipid content.Western blot analysis was conducted to detect the expression of the autophagy-associated proteins p62 and LC3-II,as well as the expression of the key signaling molecules AMPK and ULK1,in the treated cells.To further elucidate the contributions of autophagy and AMPK,we used chloroquine(CQ)to inhibit autophagy and compound C(CC)to inhibit AMPK activity.In parallel,wild-type mice and mGluR5 knockout(KO)mice fed a normal chow diet or a high-fat diet(HFD)were used to evaluate the effect of mGluR5 inhibition in vivo.RESULTS mGluR5 inhibition by MPEP attenuated hepatocellular steatosis and increased LC3-II and p62 protein expression.The autophagy inhibitor CQ reversed the effects of MPEP.In addition,MPEP promoted AMPK and ULK1 expression in HepG2 cells exposed to FFAs.MPEP treatment led to the nuclear translocation of transcription factor EB,which is known to promote p62 expression.This effect was negated by the AMPK inhibitor CC.mGluR5 KO mice presented reduced body weight,improved glucose tolerance and reduced hyperlipidemia when fed a HFD.Additionally,the livers of HFD-fed mGluR5 KO mice presented increases in LC3-II and p62.CONCLUSION Our results suggest that mGluR5 inhibition promoted autophagy and reduced hepatocyte steatosis through activation of the AMPK signaling pathway.These findings reveal a new functional mechanism of mGluR5 as a target in the treatment of MASLD.
基金supported by Grants of the National Natural Science Foundation of China(82073831)Natural Science Foundation of Chongqing(CSTB2023NSCQ-MSX0656)China Postdoctoral Science Foundation(2023M733889).
文摘Glutamate is an essential excitatory neurotransmitter in the brain,playing a vital role in regulating synaptic activity and maintaining the homeostasis of the cerebral environment but also serves as a central hub for neuronal injury and inflammatory responses.In various pathological conditions,such as ischemic stroke,glutamate is released and accumulates excessively in the brain,leading to heightened stimulation of neurons and excitotoxicity.This phenomenon positions glutamate as a primary inducing factor for neuronal damage following cerebral ischemia.Glutamate exerts its effects primarily through two types of receptors:ionotropic andmetabotropic glutamate receptors,both of which are extensively distributed throughout the hippocampus and cortical regions of the brain.Ionotropic receptors mediate rapid excitatory neurotransmission upon activation by glutamate;these are mainly categorized into N-methyl-D-aspartate receptors(NMDARs),α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid receptors(AMPARs),and kainate receptors(KARs).Conversely,metabotropic receptors function asG-protein-coupled receptors(GPCR)facilitating glutamatergic cellular effects via intracellular secondmessenger.With the comprehensive investigation of glutamate receptors and their structural characteristics,our understanding of the nerve damage and protective mechanisms associated with glutamate receptors in ischemic stroke is progressively advancing.Consequently,exploring the role of glutamate receptors and their downstream signaling pathways in cerebral ischemia can provide a robust theoretical foundation for targeted therapies aimed at treating cerebral ischemia,stroke,and related disorders.This article reviews the function of glutamate receptors and theirmediated downstreamsignal transduction pathways in the context of ischemic brain injury.
基金supported by NIH/NCI ROICA140988-01 to JWpartially supported by Chinese Scholar Council to HY。
文摘Glutamine and glutamate are major bioenergy substrates for normal and cancer cell growth.Cancer cells need more biofuel than normal tissues for energy supply,anti-oxidation activity and biomass production.Genes related to metabolic chains in many cancers are somehow mutated,which makes cancer cells more glutamate dependent.Meanwhile,glutamate is an excitatory neurotransmitter for conducting signals through binding with different types of receptors in central neuron system.Interestingly,increasing evidences have shown involvement of glutamate signaling,guided through their receptors,in human malignancy.Dysregulation of glutamate transporters,such as excitatory amino acid transporter and cystine/glutamate antiporter system,also generates excessive extracellular glutamate,which in turn,activates glutamate receptors on cancer cells and results in malignant growth.These features make glutamate an attractive target for anti-cancer drug development with some glutamate targeted but blood brain barrier impermeable anti-psychosis drugs under consideration.We discussed the relevant progressions and drawbacks in this field herein.
基金supported by the National Natural Science Foundation of China, No. 81171168Shanghai Science and Technology Committee, No. 10140903200
文摘The present study established a rat model of global cerebral ischemia induced by chest compression for six minutes to dynamically observe expressional changes of three glutamate transporters in the cerebral cortex and hippocampus. After 24 hours of ischemia, expression of glutamate transporter-1 significantly decreased in the cerebral cortex and hippocampus, which was accompanied by neuronal necrosis. At 7 days post-ischemia, expression of excitatory amino acid carrier 1 decreased in the hippocampal CA1 region and cortex, and was accompanied by apoptosis Expression of glutamate-aspartate transporter remained unchanged at 6 hours 7 days after ischemia. These results suggested that glutamate transporter levels were altered at different periods of cerebral ischemia.
基金supported by the National Natural Science Foundation of China(No.30230130 and No.30400129)the Ministry of Science and Technology of China(No.2003CB515405,No.2005CB522406)+1 种基金the Program for Changjiang Scholars and Innovative Research Team of Ministry of Education of ChinaShanghai Municipal Commission for Science and Technology(No.06JC14008).
文摘Objective To investigate whether environmental cues associated with different properties of morphine could regulate the extracellular levels of glutamate and y-aminobutyric acid （GABA） in the hippocampal ventral subiculum, which play a critical role in the reinstatement of drug-seeking behavior induced by environmental cues. Methods Conditioning place preference （CPP） and conditioning place aversion （CPA） models were used to establish environment associated with rewarding and aversive properties of morphine respectively. Microdialysis and high performance liquid chromatography were used to measure the extracelluar level of glutamate and GABA in the ventral subiculum under these environmental cues. Results Exposure to the environmental cues associated with rewarding properties of morphine resulted in a decrease （approximately 11%） of extracellular level of GABA in ventral subiculum, and exposure to the environmental cues associated with aversive properties of morphine resulted in an increase （approximately 230%） of extracellular level of glutamate in ventral subiculum. Conclusion Environmental cues associated with different properties of morphine modulate the release of distinct neurotransmitters in the hippocampal ventral subiculum possibly through different neural circuit.
文摘A full_length cDNA has been cloned encoding nicotinamide adenine dinucleotide phosphate_specific glutamate dehydrogenase (NADP_GDH) from Chlorella sorokiniana with the RT_PCR method. The complete nucleotide sequence of NADP_GDH gene had 94% homology to the previously reported one . The NADP_GDH gene was constructed into a vector highly expressed in plants. The specific activity of NADP_GDH in transformants was detected, but not in the control plants. All transformed shoots on MS medium containing lower concentration of nitrogen and the transformed seedlings grown in lower concentration of nitrogen vermiculite had higher growth rate and more leaves than the control plants. Transformed leaf discs cultured on MS medium containing different nitrogen concentrations had more chlorophyll contents compared to the controls. These results suggested that exogenous NADP_GDH may enhance the absorption and utilization to ammonium in plants. The increased weight of transformed leaf discs cultured on medium supplemented with different concentrations of phosphinothricin (PPT) was more than that of control discs. 0.5 μg/mL PPT could be used as a selecting drug instead of kanamycin to develop the transformants. These results suggested that the NADP_GDH gene might be used as a new selecting gene in the future research of plant gene engineering.
基金supported by the National Natural Science Foundation of China,Nos.81871408 and 81271631(to XMW)National Science Foundation for Young Scientists of China,No.81801658(to YZ)+1 种基金Outstanding Scientific Fund of Shengjing Hospital,No.201402(to XMW)345 Talent Support Project of Shengjing Hospital,No.30B(to YZ)。
文摘Maintaining glutamate homeostasis after hypoxic ischemia is important for synaptic function and neural cell activity,and regulation of glutamate transport between astrocyte and neuron is one of the important modalities for reducing glutamate accumulation.However,further research is needed to investigate the dynamic changes in and molecular mechanisms of glutamate transport and the effects of glutamate transport on synapses.The aim of this study was to investigate the regulatory mechanisms underlying Notch pathway mediation of glutamate transport and synaptic plasticity.In this study,Yorkshire neonatal pigs(male,age 3 days,weight 1.0–1.5 kg,n=48)were randomly divided into control(sham surgery group)and five hypoxic ischemia subgroups,according to different recovery time,which were then further subdivided into subgroups treated with dimethyl sulfoxide or a Notch pathway inhibitor(N-[N-(3,5-difluorophenacetyl-l-alanyl)]-S-phenylglycine t-butyl ester).Once the model was established,immunohistochemistry,immunofluorescence staining,and western blot analyses of Notch pathway-related proteins,synaptophysin,and glutamate transporter were performed.Moreover,synapse microstructure was observed by transmission electron microscopy.At the early stage(6–12 hours after hypoxic ischemia)of hypoxic ischemic injury,expression of glutamate transporter excitatory amino acid transporter-2 and synaptophysin was downregulated,the number of synaptic vesicles was reduced,and synaptic swelling was observed;at 12–24 hours after hypoxic ischemia,the Notch pathway was activated,excitatory amino acid transporter-2 and synaptophysin expression was increased,and the number of synaptic vesicles was slightly increased.Excitatory amino acid transporter-2 and synaptophysin expression decreased after treatment with the Notch pathway inhibitor.This suggests that glutamate transport in astrocytes-neurons after hypoxic ischemic injury is regulated by the Notch pathway and affects vesicle release and synaptic plasticity through the expression of synaptophysin.
文摘Glutamate is the predominant excitatory neurotransmitter in the human brain and it has been shown that prolonged activation of the glutamatergic system leads to nerve damage and cell death.Following release from the pre-synaptic neuron and synaptic transmission,glutamate is either taken up into the presynaptic neuron or neighbouring glia by transmembrane glutamate transporters.Excitatory amino acid transporter(EAAT)1 and EAAT2 are Na+-dependant glutamate transporters expressed predominantly in glia cells of the central nervous system.As the most abundant glutamate transporters,their primary role is to modulate levels of glutamatergic excitability and prevent spill over of glutamate beyond the synapse.This role is facilitated through the binding and transportation of glutamate into astrocytes and microglia.The function of EAAT1 and EAAT2 is heavily regulated at the levels of gene expression,post-transcriptional splicing,glycosylation states and cell-surface trafficking of the protein.Both glutamatergic dysfunction and glial dysfunction have been proposed to be involved in psychiatric disorder.This review will present an overview of the roles that EAAT1 and EAAT2 play in modulating glutamatergic activity in the human brain,and mount an argument that these two transporters could be involved in the aetiologies of schizophrenia and affective disorders as well as represent potential drug targets for novel therapies for those disorders.
基金Supported by Guangdong Natural Science Foundation(The effects of "Treatment from Gan"on Regulation of A-type Potassium Channels by KChIP/Kv4 in the pathomechanism of Refractory Epilepsy,No.2014A030310052)National Natural Science Foundation of China(Study on Regulation of A-type Potassium Channels by KChIP/Kv4 in the Pathomechanism of Refractory Epilepsy and the Effects of "Treatment from Gan",No.81503564)
文摘OBJECTIVE: To investigate the antiepileptic effects of Chaihushugan decoction(CHSGD) in rats with pentylenetetrazole(PTZ)-induced seizures and to discuss the impact of CHSGD on glutamate metabolism, a hypothesized underlying mechanism of seizure reduction.METHODS: Fifty Wistar rats were divided randomly into either control(n = 10) or experimental(n = 40)groups. Rats in the control group were administered physiological saline intraperitoneally. A subconvulsive dose of PTZ(35 mg/kg) was administered intraperitoneally to rats in the experimental group to induce seizures. The fully PTZ-kindled rats were then randomly divided into five subgroups(n = 8 each) based on the following treatment categories: physiological saline, VPA(200 mg/kg), CHSGD(2.5 g/kg), CHSGD(5 g/kg), or CHSGD(10 g/kg),administered orally once per day, respectively. On day 28 following initiation of drug treatment, seizures were monitored. The rats were then sacrificed, and hippocampal dissections were performed for subsequent studies.RESULTS: CHSGD significantly prolonged the latency of myoclonic, clonic, and tonic seizures, while decreasing overall seizure rates in the kindled rats.The measured concentrations of 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl) amino]-2-deoxy-d-glucose(2-NBDG) and glutamate were significantly lower in the hippocampi of kindled rats in groups treated with CHSGD compared with those treated with PTZ alone. In addition, CHSGD was found to up-regulate both the expression of glutamate transporter-1(GLT-1) protein and the activity of glutamine synthetase(GS) in the hippocampi of kindled rats.CONCLUSION: These results suggest that CHSGD has antiepileptic effects on PTZ-induced seizures.The results further suggest an increase in glutamate metabolism at the synaptic cleft is a putative underlying mechanism of seizure reduction.
基金Supported by the National Institute of Diabetes and Digestive Kidney Diseases Grant R01-DK063142 and R01-DK33209
文摘Glutamate is the major excitatory neurotransmitter in the mammalian central nervous system (CNS). Packaging and storage of glutamate into glutamatergic neuronal vesicles require ATP-dependent vesicular glutamate uptake systems, which utilize the electrochemical proton gradient as a driving force. Three vesicular glutamate transporters (VGLUT1-3) have been recently identified from neuronal tissue where they play a key role to maintain the vesicular glutamate level. Recently, it has been demonstrated that glutamate signaling is also functional in peripheral neuronal and non-neuronal tissues, and occurs in sites of pituitary, adrenal, pineal glands, bone, GI tract, pancreas,skin, and testis. The glutamate receptors and VGLUTs in digestivesystem have been found in both neuronal and endocrinal cells. The glutamate signaling in the digestive system may have significant relevance to diabetes and GI tract motility disorders. This review will focus on the most recent update of molecular physiology of digestive VGLUTs.
基金the Scientific and Technological Research Project of Jiangxi Provincial Public Health Bureau,No.20071090
文摘BACKGROUND： Injection of glutamate （Glu） in normal animals can cause neuronal c-Fos expression; however, whether Glu can induce spinal neuronal c-Fos expression in pain models is unclear. OBJECTIVE： To examine the effects of intraplantar and intrathecal injection of Glu on c-Fos expression in the L5 spinal cord dorsal horn Ⅰ/Ⅱ and Ⅲ/Ⅳ layers after spinal nerve ligation, and to study the effects of the N-methyI-D-aspartic acid （NMDA） receptor antagonist, D-2-amino-5-phosphonopentanoate （D-AP5）, and a selective group I mGluR antagonist, 7-hydroyiminocyclo propan[a]chromen-lacarboxylic acid ethyl ester （cpccoEt）. DESIGN, TIME AND SETTING： A randomized, controlled animal study was performed at the Department of Pharmacology, Oral Anatomy, and Neurobiology, Osaka University Graduate School of Dentistry, from December 2005 to December 2006. MATERIALS： Glu （5 μmol）, D-AP5 （50 nmot） and cpccoEt （250 nmol） were provided by Wako Pure Chemical Industries, Osaka, Japan, and diluted in saline （50 μL）. The pH of all solutions was adjusted to 7.4. METHODS： Twelve rats were randomly divided into sham operation （n = 6） and spinal nerve ligation （SNL; n = 6） groups for behavioral assessments of neuropathic pain after ligation surgery of the left L5-6 nerve segment. Another 60 rats were randomly divided into sham operation, SNL, saline-intraplantar, saline-intrathecal, Glu-intraplantar, Glu-intrathecal, D-AP5-intrathecal, Glu-D-AP5-intrathecal, cpccoEt-intrathecal, and Glu-cpccoEt-intrathecal groups, with 6 rats in each group. All groups except sham operation group received a similar SNL. On day 14, rats received a 50-μL injection of saline, Glu, D-AP5, and/or cpccoEt into the left intraplantar or intrathecal L5-4 segments. MAIN OUTCOME MEASURES： The number of c-Fos positive neurons in both Ⅰ/Ⅱ and Ⅲ/Ⅳ spinal layers at L6 was observed using immunohistochemistry 2 hours after administration. RESULTS： （1） SNL increased the level of c-Fos expression in two sides of the spinal cord, particularly on Ⅲ/Ⅳ spinal layers of the ligated side. （2） Intraplantar or intrathecal administration of saline significantly increased the c-Fos labeled neurons in Ⅰ/Ⅱ spinal layers of the ligated side, compared with SNL alone （P 〈 0.01）. （3） Intraplantar Glu （5 μmol） increased the number of c-Fos positive neurons in Ⅰ/Ⅱ spinal layers compared with intraplantar saline （P〈 0.01）. （4） The number of c-Fos neurons in Ⅰ/Ⅱ spinal layers on both the ipsilateral and contralateral side after intraplantar Glu was lower than intrathecal Glu （P〈 0.01）, with a 3-fold higher induction by intrathecal Glu. （5） Co-administration of D-AP5 or cpccoEt reduced the effects of intrathecal Glu （P 〈 0.01）. CONCLUSION： Intrathecal Glu increases c-Fos expression more than intraplantar Glu. Antagonists of NMDA and group I mGluRs block this effect.
基金Supported by grants from the Ministerio de Ciencia y Tecnología, No. SAF2002-00851 and SAF2005-06089 and from Ministerio de Sanidad, No. Red G03-155 and PI050253 of Spain and by grants from Consellería de Empresa, Universidad y Ciencia, and de Sanidad, Generalitat Valenciana, No. Grupos03/001, GV04B-055, GV04B-012, GVS05/082 and ACOMP06/005 and AP-005/06
文摘Patients with liver disease may present hepatic enceph- alopathy (HE), a complex neuropsychiatric syndrome covering a wide range of neurological alterations, including cognitive and motor disturbances. HE reduces the quality of life of the patients and is associated with poor prognosis. In the worse cases HE may lead to coma or death. The mechanisms leading to HE which are not well known are being studied using animal models. The neurological alterations in HE are a consequence of impaired cerebral function mainly due to alterations in neurotransmission. We review here some studies indicating that alterations in neurotransmission associated to different types of glutamate receptors are responsible for some of the cognitive and motor alterations present in HE. These studies show that the function of the signal transduction pathway glutamate-nitric oxide-cGMP associated to the NMDA type of glutamate receptors is impaired in brain in vivo in HE animal models as well as in brain of patients died of HE. Activation of NMDA receptors in brain activates this pathway and increases cGMP. In animal models of HE this increase in cGMP induced by activation of NMDA receptors is reduced, which is responsible for the impairment in learning ability in these animal models. Increasing cGMP by pharmacological means restores learning ability in rats with HE and may be a new therapeutic approach to improve cognitive function in patients with HE. However, it is necessary to previously assess the possible secondary effects.Patients with HE may present psychomotor slowing, hypokinesia and bradykinesia. Animal models of HE also show hypolocomotion. It has been shown in rats with HE that hypolocomotion is due to excessive activation of metabotropic glutamate receptors (mGluRs) in substantia nigra pars reticulata. Blocking mGluR1 in this brain area normalizes motor activity in the rats, suggesting that a similar treatment for patients with HE could be useful to treat psychomotor slowing and hypokinesia. However, the possible secondary effects of mGluR1 antagonists should be previously evaluated. These studies are setting the basis for designing therapeutic procedures to specifically treat the individual neurological alterations in patients with HE.
基金Shandong Provincial Science and Technology Plan Foundation
文摘BACKGROUND：Studies have reported that potassium channel openers exhibit a protective effect on cerebral ischemia-reperfusion injury and inhibit glutamate excitotoxicity in rats.However,the effects of the glutamate receptor 1α and glutamate transporter 1 remain poorly understood.OBJECTIVE：To investigate the prophylactic use of the adenosine triphosphate-sensitive potassium channel opener cromakalim on neurological function and cerebral infarct size,as well as glutamate receptor 1α and glutamate transporter 1 expression,in rats with cerebral ischemia-reperfusion injury,and to explore action mechanisms underlying reduced glutamate excitotoxicity and neuroprotection in rats.DESIGN,TIME AND SETTING：Randomized,controlled,animal experiment was performed at the Brain Institute,Qingdao University Medical College,Between July 2008 and April 2009.MATERIALS：Cromakalim was purchased from Sigma,USA; rabbit anti-glutamate receptor 1α polyclonal antibody was offered by Wuhan Boster,China; rabbit anti-glutamate transporter 1 polyclonal antibody was offered by Santa Cruz Biotechnology,USA.METHODS：Sixty male,Wistar rats,aged 6 months,were randomly assigned to three groups （n =20）：sham-surgery,model,and cromakalim.Intraluminal thread methods were used to establish middle cerebral artery occlusion in rats from the model and cromakalim groups.Rats from the sham-surgery group were subjected to exposed common carotid artery,external carotid artery,and internal carotid artery,without occlusion.Cromakalim （10 mg/kg） was administered 30 minutes prior to middle cerebral artery occlusion,but there was no intervention in the model and sham-surgery groups.MAIN OUTCOME MEASURES：At 24 hours post-surgery,neurological behavioral functions were evaluated using Bederson＇s test,cerebral infarction volume was determined following tetrazolium chloride staining,and glutamate receptor 1a and glutamate transporter 1 expressions were detected using immunohistochemistry.RESULTS：Following cerebral ischemia-reperfusion injury,neurological behavioral malfunctions were obvious in all mice.Focal cerebral infarction was detected in ischemic hemispheres,glutamate receptor 1α expression increased,and glutamate transporter 1 expression decreased in the ischemic hemisphere （P〈 0.05）.Compared with the model group,neurological behavioral functions significantly improved,cerebral infarction volume was significantly reduced （P〈 0.05）,glutamate receptor 1α expression was significantly decreased,and glutamate transporter 1 expression was increased in the cromakalim group （P 〈 0.05）.CONCLUSION：Improved neurological function and reduced cerebral infarction volume in rats through the preventive use of cromakalim could be related to decreased glutamate receptor 1α expression and enhanced glutamate transporter 1 expression.
基金supported by the Key Technology Research of Major Mental Illness Prevention and Treatment for the Barriers to the Recognition and Prevention of Depression and Anxiety in the General Hospital,China(No.2012BAI01B05)
文摘In recent years, more attention has been paid to the role of the glutamate transporter 1 （GLT-1, EAAT2） in major depressive disorder （MDD）. However, experimental data on brain GLT-1 levels are, to some extent, inconsistent in human postmortem and animal studies, These discrepancies imply that the role of GLT-1 in the pathophysiology of MDD and the action of antidepressants remain obscure. This work was designed to study the impact of chronic unpredictable stress （CUS） for 2 ses- sions per day for 35 days and four weeks of fluoxetine （FLX） on depressive-like behaviors in rats, as well as the concomitant expression of the GLT-1 protein in the hippocampus. Behavioral changes were assessed by the sucrose preference and open field tests. GLT-1 levels were detected by immunohisto- chemistry and Western blot analysis. Our study demonstrated that the animals exposed to CUS showed depressive-like behaviors and exhibited a significant decrease in GLT-1 expression in the hippocampus. Chronic FLX treatment reversed the behavioral deficits and the CUS-induced decrease in GLT-1 levels. Taken together, our results support the reduction of GLT-1 in human postmortem studies in MDD and suggest that GLT-1 may be involved in the antidepressant activity of FLX. Our studies further support the notion that GLT-1 is an attractive candidate molecule associated with the fundamental processes of MDD and may be a potential, and novel pharmacological target for the treatment of MDD.
文摘Glutamate is a regulated molecule in the mammalian testis. Extracellular regulation of glutamate in the body is determined largely by the expression of plasmalemmal glutamate transporters. We have examined by PCR, western blotting and immunocytochemistry the expression of a panel of sodium-dependent plasmalemmal glutamate transporters in the rat testis. Proteins examined included： glutamate aspartate transporter （GLAST）, glutamate transporter 1 （GLT1）, excitatory amino acid carrier 1 （EAAC1）, excitatory amino acid transporter 4 （EAAT4） and EAAT5. We demonstrate that many of the glutamate transporters in the testis are alternately spliced. GLAST is present as exon-3- and exon-9-skipping forms. GLT1 was similarly present as the alternately spliced forms GLT1 b and GLTlc, whereas the abundant brain form （GLTla） was detectable only at the mRNA level. EAAT5 was also strongly expressed, whereas EAAC1 and EAAT4 were absent. These patterns of expression were compared with the patterns of endogenous glutamate localization and with patterns of D-aspartate accumulation, as assessed by immunocytochemistry. The presence of multiple glutamate transporters in the testis, including unusually spliced forms, suggests that glutamate homeostasis may be critical in this organ. The apparent presence of many of these transporters in the testis and sperm may indicate a need for glutamate transport by such cells.
基金supported by the National Basic Research Program of China(2015CB553504)the National Natural Science Foundation of China(81471350 and 81671321)the Natural Science Foundation of Ningbo Municipality,Zhejiang Province,China(2015A610193)
文摘Activation of presynaptic group II metabotropic glutamate receptors（mGluR2/3） inhibits drug reward and drug-seeking behavior, but the role of N-acetylaspartylglutamate（NAAG）, an agonist of endogenous mGluR2/3,in heroin reward and heroin-seeking behavior remained unclear. Here, we aimed to explore the effects of exogenous NAAG on heroin self-administration and heroinseeking behavior. First, rats were trained to self-administer heroin under a fixed ratio 1（FR1） schedule for 10 days,then received NAAG（50 or 100μg/10 μL in each nostril）in the absence or presence of LY341495（1 mg/kg, i.p.）, an antagonist of mGluR2/3, on day 11 and the effects of NAAG on heroin self-administration under FR1 were recorded for 3 consecutive days. Motivation was assessed in heroin self-administration under a progressive ratio schedule on day 11 in another 5 groups with the same doses of NAAG. Additional rats were withdrawn for 14 days after 14 days of heroin self-administration, then received the same pharmacological pretreatment and were tested for heroin-seeking behaviors induced by heroin priming or cues. The results showed that intranasal administration of NAAG significantly decreased intravenous heroin selfadministration on day 12, but not on day 11. Pretreatment with LY341495 prior to testing on day 12 prevented the inhibitory effect of NAAG on heroin reinforcement. The break-point for reward motivation was significantly reduced by NAAG. Moreover, NAAG also significantly inhibited the heroin-seeking behaviors induced by heroinpriming or cues and these were restored by pretreatment with LY341495. These results demonstrated that NAAG,via activation of presynaptic mGluR2/3, attenuated the heroin reinforcement, heroin motivational value, and heroin-seeking behavior, suggesting that it may be used as an adjunct treatment for heroin addiction.
