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
The effects of bis(7) tacrine, a novel dimeric acetylcholinesterase (AChE) inhibitor, on glutamate induced cell injury were investigated in primary cerebral cortical neurons of rats. Exposure of cultured neurons (1...The effects of bis(7) tacrine, a novel dimeric acetylcholinesterase (AChE) inhibitor, on glutamate induced cell injury were investigated in primary cerebral cortical neurons of rats. Exposure of cultured neurons (12 days after plating) to 0.5 mmol/L glutamate for 30 min resulted in significant cell damage. Pretreatment with bis(7) tacrine (0.03 1.0 μmol/L) reduced the glutamate induced neurotoxicity in a concentration dependent manner and the maximal response was seen at 1 μmol/L with approximately 30% protection. A receptor binding assay showed that bis(7) tacrine can completely displace MK 801 binding to rat cortical membrane with an IC 50 of 0.57 μmol/L. These findings suggest that bis(7) tacrine can directly interact with N methyl D aspartate receptor channel complex, which may contribute to the inhibitor's protective effects against glutamate induced excitotoxicity. Thus, it is possible that anti glutamate/anti AChE synergism is responsible for potentially better Alzheimer's therapy of bis(7) tacrine relative to tacrine.展开更多
Septic encephalopathy is a frequent complication of sepsis,but there are few studies examining the role of micro RNAs(mi Rs) in its pathogenesis.In this study,a mi R-219 mimic was transfected into rat hippocampal ne...Septic encephalopathy is a frequent complication of sepsis,but there are few studies examining the role of micro RNAs(mi Rs) in its pathogenesis.In this study,a mi R-219 mimic was transfected into rat hippocampal neurons to model mi R-219 overexpression.A protective effect of mi R-219 was observed for glutamate-induced neurotoxicity of rat hippocampal neurons,and an underlying mechanism involving calmodulin-dependent protein kinase II γ(Ca MKIIγ) was demonstrated.mi R-219 and Ca MKIIγ m RNA expression induced by glutamate in hippocampal neurons was determined by quantitative real-time reverse transcription-polymerase chain reaction(q RT-PCR).After neurons were transfected with mi R-219 mimic,effects on cell viability and apoptosis were measured by 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide(MTT) assay and flow cytometry.In addition,a luciferase reporter gene system was used to confirm Ca MKIIγ as a target gene of mi R-219.Western blot assay and rescue experiments were also utilized to detect Ca MKIIγ expression and further verify that mi R-219 in hippocampal neurons exerted its effect through regulation of Ca MKIIγ.MTT assay and q RT-PCR results revealed obvious decreases in cell viability and mi R-219 expression after glutamate stimulation,while Ca MKIIγ m RNA expression was increased.MTT,flow cytometry,and caspase-3 activity assays showed that mi R-219 overexpression could elevate glutamate-induced cell viability,and reduce cell apoptosis and caspase-3 activity.Moreover,luciferase Ca MKIIγ-reporter activity was remarkably decreased by co-transfection with mi R-219 mimic,and the results of a rescue experiment showed that Ca MKIIγ overexpression could reverse the biological effects of mi R-219.Collectively,these findings verify that mi R-219 expression was decreased in glutamate-induced neurons,Ca MKIIγ was a target gene of mi R-219,and mi R-219 alleviated glutamate-induced neuronal excitotoxicity by negatively controlling Ca MKIIγ expression.展开更多
Ciliary neurotrophic factor has neuroprotective effects mediated through signal transducer and Janus kinase(JAK) 2/activator of transcription 3(STAT3) and phosphatidylinositol 3-kinase(PI3 K)/Akt signaling pathw...Ciliary neurotrophic factor has neuroprotective effects mediated through signal transducer and Janus kinase(JAK) 2/activator of transcription 3(STAT3) and phosphatidylinositol 3-kinase(PI3 K)/Akt signaling pathways.Whether ciliary neurotrophic factor is neuroprotective for glutamate-induced excitotoxicity of dorsal root ganglion neurons is poorly understood.In the present study,the in vitro neuroprotective effects of ciliary neurotrophic factor against glutamate-induced excitotoxicity were determined in a primary culture of dorsal root ganglion neurons from Wistar rat embryos at embryonic day 15.Whether the JAK2/STAT3 and PI3 K/Akt signaling pathways were related to the protective effects of ciliary neurotrophic factor was also determined.Glutamate exposure inhibited neurite outgrowth,cell viability,and growth-associated protein 43 expression and promoted apoptotic neuronal cell death,all of which were reversed by the administration of exogenous ciliary neurotrophic factor.Additionally,preincubation with either JAK2 inhibitor AG490 or PI3 K inhibitor LY294002 blocked the neuroprotective effect of ciliary neurotrophic factor.These data indicate that the two pathways JAK2/STAT3 and PI3 K/Akt play major roles in mediating the in vitro neuroprotective effects of ciliary neurotrophic factor on dorsal root ganglion neurons with glutamate-induced neurotoxicity.展开更多
To investigate the intracellular mechanism that interleukin 1β (IL 1β) facilitates epileptic seizure and neuronal damage, the effect of IL 1β alone or IL 1β plus glutamate (Glu) on the intracellular free calci...To investigate the intracellular mechanism that interleukin 1β (IL 1β) facilitates epileptic seizure and neuronal damage, the effect of IL 1β alone or IL 1β plus glutamate (Glu) on the intracellular free calcium ([Ca 2+ ] i) of single cultured hippocampal neuron was examined by using EPC 9 light electricity measurement system. The results showed that IL 1β of different concentrations (5×10 3 U/L, 10×10 3 U/L, 20×10 3 U/L, 30×10 3 U/L, 50×10 3 U/L, 100×10 3 U/L) failed to affect the neuronal [Ca 2+ ] i, but IL 1β could facilitate the augmentation of neuronal [Ca 2+ ] i induced by Glu in a dose dependent pattern. MK 801 inhibited the effect of Glu on [Ca 2+ ] i, and also inhibited the effect of IL 1β on [Ca 2+ ] i induced by Glu, while verapamil did not influence the effect of Glu or IL 1β. It is concluded that IL 1β, as a neuromodulator, can facilitate the activation of NMDA receptor by Glu, induce the increase of intracellular calcium, which enhances the excitement of neuron.展开更多
Excess extracellular glutamate leads to excitotoxicity,which induces neuronal death through the overactivation of N-methyl-D-aspartate receptors(NMDARs).Excitotoxicity is thought to be closely related to various acute...Excess extracellular glutamate leads to excitotoxicity,which induces neuronal death through the overactivation of N-methyl-D-aspartate receptors(NMDARs).Excitotoxicity is thought to be closely related to various acute and chronic neurological disorders,such as stroke and Alzheimer’s disease.Polygalasaponin F(PGSF)is a triterpenoid saponin monomer that can be isolated from Polygala japonica,and has been reported to protect cells against apoptosis.To investigate the mechanisms underlying the neuroprotective effects of PGSF against glutamateinduced cytotoxicity,PGSF-pretreated hippocampal neurons were exposed to glutamate for 24 hours.The results demonstrated that PGSF inhibited glutamate-induced hippocampal neuron death in a concentration-dependent manner and reduced glutamate-induced Ca^(2+)overload in the cultured neurons.In addition,PGSF partially blocked the excess activity of NMDARs,inhibited both the downregulation of NMDAR subunit NR2A expression and the upregulation of NMDAR subunit NR2B expression,and upregulated the expression of phosphorylated cyclic adenosine monophosphate-responsive element-binding protein and brain-derived neurotrophic factor.These findings suggest that PGSF protects cultured hippocampal neurons against glutamate-induced cytotoxicity by regulating NMDARs.The study was approved by the Institutional Animal Care Committee of Nanchang University(approval No.2017-0006)on December 29,2017.展开更多
BACKGROUND: Nerve growth factor (NGF) attenuates glutamate-induced injury to hippocampal neurons, and the human tumor suppressor gene phosphatase and tensin homologue deleted on chromosome 10 (PTEN) promotes neur...BACKGROUND: Nerve growth factor (NGF) attenuates glutamate-induced injury to hippocampal neurons, and the human tumor suppressor gene phosphatase and tensin homologue deleted on chromosome 10 (PTEN) promotes neuronal apoptosis. However, effects of PTEN in NGF-mediated neuroprotection against glutamate excitotoxicity remain poorly understood. OBJECTIVE: To investigate the relationship between NGF inhibition of glutamate-induced injury and PTEN. DESIGN, TIME AND SE'I'rlNG: The randomized, controlled, in vitro study was performed at the Department of Pathophysiology, Medical School of Nantong University, China from October 2007 to March 2008. MATERIALS: Glutamate, NGF, 4, 6-diamidino-2-phenyl-indolediacetate, 3-[4, 5-dimethylthiazol-2-yl]- 2, 5-diphenyl tetrazoliumbromide (M-I-F), and lactate dehydrogenase kit (Sigma, USA), fluorescence microscope and inverted phase contrast microscope (Olympus, Japan) were used in this study. METHODS: Hippocampal neurons were obtained from newborn (〈 24 hours) Sprague Dawley rats and cultured for 7 days. The control group was not treated with any intervention factor, the glutamate group was treated with glutamate (0.2 mmol/L), and NGF groups were treated with NGF (10, 50, 100, and 200 μg/L, respectively) prior to glutamate treatment. MAIN OUTCOME MEASURES: The MTT and lactate dehydrogenase assays were applied to evaluate viability of hippocampal neurons. Morphological changes in hippocampal neurons were observed using an inverted phase-contrast microscope, and neuronal apoptosis was detected by 4, 6-diamidino-2- phenyl-indolediacetate staining. PTEN mRNA and protein expression were measured by reverse transcription-polymerase chain reaction and Western blot analysis, respectively. RESULTS: Glutamate (0.2 mmol/L) induced significantly decreased neuronal viability and greater lactate dehydrogenase efflux compared with the control group (P 〈 0.01). However, compared with the glutamate group, cell viability significantly increased and lactate dehydrogenase efflux decreased in the NGF group with increasing NGF concentrations (P 〈 0.05 or P 〈 0.01). The apoptotic ratio and PTEN mRNA and protein expression decreased in the NGF group compared with the glutamate group (P 〈 0.01). CONCLUSION: Pretreatment with NGF exerted neuroprotective effects against glutamate-induced injury, partially through inhibition of PTEN expression and neuronal apoptosis.展开更多
During brain ischemia,excitotoxicity and peri-infarct depolarization injuries occur and cause cerebral tissue damage.Indeed,anoxic depolarization,consisting of massive neuronal depolarization due to the loss of membra...During brain ischemia,excitotoxicity and peri-infarct depolarization injuries occur and cause cerebral tissue damage.Indeed,anoxic depolarization,consisting of massive neuronal depolarization due to the loss of membrane ion gradients,occurs in vivo or in vitro during an energy failure.The neuromodulator adenosine is released in huge amounts during cerebral ischemia and exerts its effects by activating specific metabotropic receptors,namely:A_(1),A_(2A),A_(2B),and A_(3).The A_(2A)receptor subtype is highly expressed in striatal medium spiny neurons,which are particularly susceptible to ischemic damage.Evidence indicates that the A2Areceptors are upregulated in the rat striatum after stroke and the selective antagonist SCH58261 protects from exaggerated glutamate release within the first 4 hours from the insult and alleviates neurological impairment and histological injury in the following 24 hours.We recently added new knowledge to the mechanisms by which the adenosine A2Areceptor subtype participates in ischemia-induced neuronal death by performing patch-clamp recordings from medium spiny neurons in rat striatal brain slices exposed to oxygen and glucose deprivation.We demonstrated that the selective block of A2Areceptors by SCH58261 significantly reduced ionic imbalance and delayed the anoxic depolarization in medium spiny neurons during oxygen and glucose deprivation and that the mechanism involves voltage-gated K+channel modulation and a presynaptic inhibition of glutamate release by the A2Areceptor antagonist.The present review summarizes the latest findings in the literature about the possibility of developing selective ligands of A2Areceptors as advantageous therapeutic tools that may contribute to counteracting neurodegeneration after brain ischemia.展开更多
The iron chelator deferoxamine has been shown to inhibit ferroptosis in spinal cord injury.However,it is unclear whether deferoxamine directly protects neurons from ferroptotic cell death.By comparing the survival rat...The iron chelator deferoxamine has been shown to inhibit ferroptosis in spinal cord injury.However,it is unclear whether deferoxamine directly protects neurons from ferroptotic cell death.By comparing the survival rate and morphology of primary neurons and SH-SY5Y cells exposed to erastin,it was found that these cell types respond differentially to the duration and concentration of erastin treatment.Therefore,we studied the mechanisms of ferroptosis using primary cortical neurons from E16 mouse embryos.After treatment with 50μM erastin for 48 hours,reactive oxygen species levels increased,and the expression of the cystine/glutamate antiporter system light chain and glutathione peroxidase 4 decreased.Pretreatment with deferoxamine for 12 hours inhibited these changes,reduced cell death,and ameliorated cellular morphology.Pretreatment with the apoptosis inhibitor Z-DEVD-FMK or the necroptosis inhibitor necrostain-1 for 12 hours did not protect against erastin-induced ferroptosis.Only deferoxamine protected the primary cortical neurons from ferroptosis induced by erastin,confirming the specificity of the in vitro ferroptosis model.This study was approved by the Animal Ethics Committee at the Institute of Radiation Medicine of the Chinese Academy of Medical Sciences,China(approval No.DWLL-20180913)on September 13,2018.展开更多
Epilepsy is a neurological disorder caused by the pathological hyper-synchronization of neuronal discharges.The fundamental research of epilepsy mechanisms and the targets of drug design options for its treatment have...Epilepsy is a neurological disorder caused by the pathological hyper-synchronization of neuronal discharges.The fundamental research of epilepsy mechanisms and the targets of drug design options for its treatment have focused on neurons.However,approximately 30%of patients suffering from epilepsy show resistance to standard anti-epileptic chemotherapeutic agents while the symptoms of the remaining 70%of patients can be alleviated but not completely removed by the current medications.Thus,new strategies for the treatment of epilepsy are in urgent demand.Over the past decades,with the increase in knowledge on the role of glia in the genesis and development of epilepsy,glial cells are receiving renewed attention.In a normal brain,glial cells maintain neuronal health and in partnership with neurons regulate virtually every aspect of brain function.In epilepsy,however,the supportive roles of glial cells are compromised,and their interaction with neurons is altered,which disrupts brain function.In this review,we will focus on the role of glia-related processes in epileptogenesis and their contribution to abnormal neuronal activity,with the major focus on the dysfunction of astroglial potassium channels,water channels,gap junctions,glutamate transporters,purinergic signaling,synaptogenesis,on the roles of microglial inflammatory cytokines,microglia-astrocyte interactions in epilepsy,and on the oligodendroglial potassium channels and myelin abnormalities in the epileptic brain.These recent findings suggest that glia should be considered as the promising next-generation targets for designing anti-epileptic drugs that may improve epilepsy and drug-resistant epilepsy.展开更多
In this study,I focused on finding a mean of protecting against hearing loss.By infusing the cochlea with the neurotrophin factor,NT-3 alone or combined treatment with MK 801,a NMDA receptor antagonist I found hearing...In this study,I focused on finding a mean of protecting against hearing loss.By infusing the cochlea with the neurotrophin factor,NT-3 alone or combined treatment with MK 801,a NMDA receptor antagonist I found hearing loss was attenuated and spiral ganglion neuron loss was nearly totally protected indicating that the importance of the combined treatment of NT-3 and NMDA receptor antagonists in the treatment of hearing disorders.展开更多
Mitochondrial division inhibitor 1(Mdivi-1) is a selective cell-permeable inhibitor of dynamin-related protein-1(Drp1) and mitochondrial division.To investigate the effect of Mdivi-1 on cells treated with glutamat...Mitochondrial division inhibitor 1(Mdivi-1) is a selective cell-permeable inhibitor of dynamin-related protein-1(Drp1) and mitochondrial division.To investigate the effect of Mdivi-1 on cells treated with glutamate,cerebral cortex neurons isolated from neonatal rats were treated with 10 m M glutamate for 24 hours.Normal cultured cells and dimethyl sulfoxide-cultured cells were considered as controls.Apoptotic cells were detected by flow cytometry.Changes in mitochondrial morphology were examined by electron microscopy.Drp1,Bax,and casp ase-3 expression was evaluated by western blot assays and immunocytochemistry.Mitochondrial membrane potential was detected using the JC-1 probe.Twenty-four hours after 10 m M glutamate treatment,Drp1,Bax and caspase-3 expression was upregulated,Drp1 and Bax were translocated to mitochondria,mitochondrial membrane potential was decreased and the rate of apoptosis was increased.These effects were inhibited by treatment with 50 μM Mdivi-1 for 2 hours.This finding indicates that Mdivi-1 is a candidate neuroprotective drug that can potentially mitigate against neuronal injury caused by glutamate-induced excitotoxicity.展开更多
Glial glutamate transporter-1(GLT-1)is the predominant subtype of glutamate transporters and is responsible for the clearance of extracellular glutamate and for limiting the concentration of extracellular glutamate.Ou...Glial glutamate transporter-1(GLT-1)is the predominant subtype of glutamate transporters and is responsible for the clearance of extracellular glutamate and for limiting the concentration of extracellular glutamate.Our previous studies have shown that the up-regulation of GLT-1 expression plays an important role展开更多
Objective To examine the effects of Pb2+ on N-methyl-D-aspartate (NMDA)-, K+- and quisqualate(QA)/kainite(KA)-induced increases in intracellular free calcium concentration ([Ca2+],) in cultured fetal rat hippocampal n...Objective To examine the effects of Pb2+ on N-methyl-D-aspartate (NMDA)-, K+- and quisqualate(QA)/kainite(KA)-induced increases in intracellular free calcium concentration ([Ca2+],) in cultured fetal rat hippocampal neurons in order to explain the cognitive and learning deficits produced by this heavy metal. Methods Laser scanning confocal microscopy was used. Results The results clearly demonstrated that adding Pb2+ before or after NMDA/glycine stimulation selectively inhibited the stimulated increases in [Ca2+], in a concentration-dependent manner. In contrast, Pb2+ treatment did not markedly affect increases in [Ca2+], induced by an admixture of QA and KA. The minimal inhibitory effect of Pb2+ occurred at 1 μmol/L, and more than seventy percent abolition of the NMDA-stimulated increase in [Ca2+]; was observed at 100 Jμmoll/L Pb2+. Evaluation of Pb2+-induced increase in [Ca2+], response to elevating extracellular concentrations of NMDA, glycine or calcium revealed that Pb2+ was a noncompetitive antagonist of both NMDA and glycine, and a competitive antagonist of Ca2+ at NMDA receptor channels. In addition. Pb2+ inhibited depolarization-evoked increases in [Ca2+], mediated by K+ stimulation(30μmol/L). indicating that Pb2+ also depressed the voltage-dependent calcium channels. Also, the results showed that Pb2+ appeared to be able to elevate the resting levels of [Ca2+|, in cultured neurons, implying a reason for Pb2+-enhanced spontaneous release of several neurotransmitters reported in several previous studies. Conclusion Lead can inhibit NMDA-. K+-, QA/KA-jnduced increases in intracellular [Ca2+], in cultured hippocampal neurons.展开更多
Gentianine has been shown to have a protective effect on hippocampal CA1 neurons in rats subjected to recurrent febrile convulsion(FC).The present study sought to explore the possible mechanism of gentianine by intr...Gentianine has been shown to have a protective effect on hippocampal CA1 neurons in rats subjected to recurrent febrile convulsion(FC).The present study sought to explore the possible mechanism of gentianine by intraperitoneally injecting gentianine into rats with warm water-induced FC.The results revealed that neuronal organelle injury was slightly ameliorated in the hippocampal CA1 region.The level of glutamate was decreased,but the level of γ-aminobutyric acid was increased,as detected by ninhydrin staining.In addition,glutamate acid decarboxylase expression in hippocampal CA1 was increased,as determined by immunohistochemistry.The results demonstrated that gentianine can ameliorate FC-induced neuronal injury by enhancing glutamate acid decarboxylase activity,decreasing glutamate levels and increasing γ-aminobutyric acid levels.展开更多
Activation of metabotropic glutamate receptor la aggravates traumatic brain injury. The constitutively expressed protein Homerlb/c participates in delivering and anchoring metabotropic glutamate receptors in neurons. ...Activation of metabotropic glutamate receptor la aggravates traumatic brain injury. The constitutively expressed protein Homerlb/c participates in delivering and anchoring metabotropic glutamate receptors in neurons. Here, we aimed to verify whether down-regulation of Homerlb/c by RNA interference could protect cultured rat cortical neurons from traumatic injury. We showed that 36 hours after transfection of Homerlb/c small interfering RNA, metabotropic glutamate receptor la was present only in the neuronal cytoplasm, but not in the dendrites. Calcium fluorescence intensity was also decreased significantly. Moreover, lactate dehydrogenase concentration was significantly decreased in Homerlb/c small interfering RNA-transfected cells compared with that in untransfected and control small interfering RNA-transfected cells 24 hours after traumatic neuronal injury. Our findings indicate that down-regulation of Homerlb/c could reduce metabotropic glutamate receptor la transfer from the cell body to the dendrite, relieve calcium overload, and protect neurons from traumatic injury.展开更多
Glutamate(Glu)is the main excitatory amino acid in the brain and plays a pivotal role in many neurophysiological functions.Nevertheless,an excess and prolonged exposure to Glu determines the overactivation of glutam...Glutamate(Glu)is the main excitatory amino acid in the brain and plays a pivotal role in many neurophysiological functions.Nevertheless,an excess and prolonged exposure to Glu determines the overactivation of glutamate receptors(Glu Rs)with consequent impairment of cellular calcium(Ca2+)homeostasis,展开更多
The present study used cultures of primary astrocytes, isolated from neonatal rats, to verify the hypothesis that arsenite-induced neurotoxicity can influence neuronal function by altering glutamate-induced gliotransm...The present study used cultures of primary astrocytes, isolated from neonatal rats, to verify the hypothesis that arsenite-induced neurotoxicity can influence neuronal function by altering glutamate-induced gliotransmitter release. Primary astrocytes were exposed to 0, 2.5, 5, 10, 20 or 30 μM arsenite for 24 hours. Cell viability and morphological observations revealed that 5 μM arsenic exposure could induce cytotoxicity. Cells were then cultured in the presence of 0, 2.5, 5, or 10 μM arsenite for 24 hours and stimulated with 25 μM glutamate for 10 minutes. Results showed that [Ca2+]i in astrocytes exposed to 5 and 10 μM arsenite was significantly increased and levels of D-serine, γ-aminobutyric acid and glycine in cultures exposed to 2.5-10 μM arsenite were also increased. However, glutamate levels in the media were significantly increased only after treatment with 10 μM arsenite. In conclusion, our findings suggest that arsenic exposure may affect glutamate-induced gliotransmitter release from astrocytes and further disturb neuronal function.展开更多
Increasing evidence, including from our laboratory, has revealed that opening of ATP sensitive potassium channels(K-ATP channels) plays the neuronal protective roles both in vivo and in vitro. Thus K-ATP channel opene...Increasing evidence, including from our laboratory, has revealed that opening of ATP sensitive potassium channels(K-ATP channels) plays the neuronal protective roles both in vivo and in vitro. Thus K-ATP channel openers(KCOs) have been proposed as potential neuroprotectants. Our previous studies demonstrated that K-ATP channels could regulate glutamate uptake activity in PC12 cells as well as in synaptosomes of rats. Since glutamate transporters(GluTs) of astrocytes play crucial roles in glutamate uptake and KATP channels are also expressed in astrocytes, the present study showed whether and how KATP channels regulated the function of GluTs in primary cultured astrocytes. The results showed that nonselective KCO pinacidil, selective mitochondrial KCO diazoxide, novel, and blood-brain barrier permeable KCO iptakalim could enhance glutamate uptake, except for the sarcolemmal KCO P1075. Moreover pinacidil, diazoxide, and iptakalim reversed the inhibition of glutamate uptake induced by 1-methyl-4-phenylpyridinium(MPP+). These potentiated effects were completely abolished by mitochondrial K-ATP blocker 5-hydroxydecanoate. Furthermore, either diazoxide or iptakalim could inhibit MPP+-induced elevation of reactive oxygen species (ROS) and phosphorylation of protein kinases C(PKC). These findings are the first to demonstrate that activation of K-ATP channel, especially mitochondrial K-ATP channel, improves the function of GluTs in astrocytes due to reducing ROS production and downregulating PKC phosphorylation. Therefore, the present study not only reveals a novel pharmacological profile of KCOs as regulators of GluTs, but also provides a new strategy for neuroprotection.展开更多
To investigate the expression of interleukin 2 (IL 2), metabotropic glutamate receptor subunit 1 (mGluR1) and estrogen receptor (ER) in neurons of the rat central nervous system (CNS) and identify the coexistence po...To investigate the expression of interleukin 2 (IL 2), metabotropic glutamate receptor subunit 1 (mGluR1) and estrogen receptor (ER) in neurons of the rat central nervous system (CNS) and identify the coexistence possibility of these immune neuro endocrine substances in the central neurons, the tri labeling immunocytochemical technique with different species specific primary antibodies (goat anti IL 2 antibody, rabbit anti mGluR1 antibody and mouse anti ER antibody ) were used to incubate two serial neighbor sections (one for demonstrating IL 2, another for mGluR1 and ER) of the cerebral cortex, medulla oblongata and spinal cord. There were IL 2 , mGluR1 and ER immunoreactivity (IR) positive labeled neurons in the above mentioned central areas. The IL 2 IR production showed brown color, located in the cytoplasm; In the neighbor serial section, the mGluR1 IR, production showed blue black color, located on the cell membrane; the ER IR production also showed brown color, located in the cytoplasm and nuclei. There were mGluR1/ER double labeled cells in the same section, which accounted for about 50 %-60 % of the total single and double labeled neurons. It was identified by projection check of serial neighbor sections that had mGluR1/ER/IL 2 tri labeled cells, which accounted for about 30 % of total mGluR1/ER double labeled neurons. The results indicate that mGluR1, ER and Il 2 can coexist in the same rat central neurons, therefore, providing morphological basis for the theory about immune neuro endocrine network at the cellular level for the first time.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.
文摘The effects of bis(7) tacrine, a novel dimeric acetylcholinesterase (AChE) inhibitor, on glutamate induced cell injury were investigated in primary cerebral cortical neurons of rats. Exposure of cultured neurons (12 days after plating) to 0.5 mmol/L glutamate for 30 min resulted in significant cell damage. Pretreatment with bis(7) tacrine (0.03 1.0 μmol/L) reduced the glutamate induced neurotoxicity in a concentration dependent manner and the maximal response was seen at 1 μmol/L with approximately 30% protection. A receptor binding assay showed that bis(7) tacrine can completely displace MK 801 binding to rat cortical membrane with an IC 50 of 0.57 μmol/L. These findings suggest that bis(7) tacrine can directly interact with N methyl D aspartate receptor channel complex, which may contribute to the inhibitor's protective effects against glutamate induced excitotoxicity. Thus, it is possible that anti glutamate/anti AChE synergism is responsible for potentially better Alzheimer's therapy of bis(7) tacrine relative to tacrine.
基金supported by the National Natural Science Foundation of China,No.81101159the Natural Science Foundation of Jiangsu Province of China,No.BK20151268
文摘Septic encephalopathy is a frequent complication of sepsis,but there are few studies examining the role of micro RNAs(mi Rs) in its pathogenesis.In this study,a mi R-219 mimic was transfected into rat hippocampal neurons to model mi R-219 overexpression.A protective effect of mi R-219 was observed for glutamate-induced neurotoxicity of rat hippocampal neurons,and an underlying mechanism involving calmodulin-dependent protein kinase II γ(Ca MKIIγ) was demonstrated.mi R-219 and Ca MKIIγ m RNA expression induced by glutamate in hippocampal neurons was determined by quantitative real-time reverse transcription-polymerase chain reaction(q RT-PCR).After neurons were transfected with mi R-219 mimic,effects on cell viability and apoptosis were measured by 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide(MTT) assay and flow cytometry.In addition,a luciferase reporter gene system was used to confirm Ca MKIIγ as a target gene of mi R-219.Western blot assay and rescue experiments were also utilized to detect Ca MKIIγ expression and further verify that mi R-219 in hippocampal neurons exerted its effect through regulation of Ca MKIIγ.MTT assay and q RT-PCR results revealed obvious decreases in cell viability and mi R-219 expression after glutamate stimulation,while Ca MKIIγ m RNA expression was increased.MTT,flow cytometry,and caspase-3 activity assays showed that mi R-219 overexpression could elevate glutamate-induced cell viability,and reduce cell apoptosis and caspase-3 activity.Moreover,luciferase Ca MKIIγ-reporter activity was remarkably decreased by co-transfection with mi R-219 mimic,and the results of a rescue experiment showed that Ca MKIIγ overexpression could reverse the biological effects of mi R-219.Collectively,these findings verify that mi R-219 expression was decreased in glutamate-induced neurons,Ca MKIIγ was a target gene of mi R-219,and mi R-219 alleviated glutamate-induced neuronal excitotoxicity by negatively controlling Ca MKIIγ expression.
基金supported by the Natural Science Foundation of Shandong Province of China,No.ZR2014HQ065a grant from the Medical Science and Technology Development Project of Shandong Province of China,No.2015WS0445
文摘Ciliary neurotrophic factor has neuroprotective effects mediated through signal transducer and Janus kinase(JAK) 2/activator of transcription 3(STAT3) and phosphatidylinositol 3-kinase(PI3 K)/Akt signaling pathways.Whether ciliary neurotrophic factor is neuroprotective for glutamate-induced excitotoxicity of dorsal root ganglion neurons is poorly understood.In the present study,the in vitro neuroprotective effects of ciliary neurotrophic factor against glutamate-induced excitotoxicity were determined in a primary culture of dorsal root ganglion neurons from Wistar rat embryos at embryonic day 15.Whether the JAK2/STAT3 and PI3 K/Akt signaling pathways were related to the protective effects of ciliary neurotrophic factor was also determined.Glutamate exposure inhibited neurite outgrowth,cell viability,and growth-associated protein 43 expression and promoted apoptotic neuronal cell death,all of which were reversed by the administration of exogenous ciliary neurotrophic factor.Additionally,preincubation with either JAK2 inhibitor AG490 or PI3 K inhibitor LY294002 blocked the neuroprotective effect of ciliary neurotrophic factor.These data indicate that the two pathways JAK2/STAT3 and PI3 K/Akt play major roles in mediating the in vitro neuroprotective effects of ciliary neurotrophic factor on dorsal root ganglion neurons with glutamate-induced neurotoxicity.
文摘To investigate the intracellular mechanism that interleukin 1β (IL 1β) facilitates epileptic seizure and neuronal damage, the effect of IL 1β alone or IL 1β plus glutamate (Glu) on the intracellular free calcium ([Ca 2+ ] i) of single cultured hippocampal neuron was examined by using EPC 9 light electricity measurement system. The results showed that IL 1β of different concentrations (5×10 3 U/L, 10×10 3 U/L, 20×10 3 U/L, 30×10 3 U/L, 50×10 3 U/L, 100×10 3 U/L) failed to affect the neuronal [Ca 2+ ] i, but IL 1β could facilitate the augmentation of neuronal [Ca 2+ ] i induced by Glu in a dose dependent pattern. MK 801 inhibited the effect of Glu on [Ca 2+ ] i, and also inhibited the effect of IL 1β on [Ca 2+ ] i induced by Glu, while verapamil did not influence the effect of Glu or IL 1β. It is concluded that IL 1β, as a neuromodulator, can facilitate the activation of NMDA receptor by Glu, induce the increase of intracellular calcium, which enhances the excitement of neuron.
基金supported by the National Natural Science Foundation of China,Nos.31971035(to BML),31771182(to BML),81471116(to BML)the Natural Science Foundation of Jiangxi Province of China,Nos.20171BAB204019(to CS),20192ACB20022(to CS)。
文摘Excess extracellular glutamate leads to excitotoxicity,which induces neuronal death through the overactivation of N-methyl-D-aspartate receptors(NMDARs).Excitotoxicity is thought to be closely related to various acute and chronic neurological disorders,such as stroke and Alzheimer’s disease.Polygalasaponin F(PGSF)is a triterpenoid saponin monomer that can be isolated from Polygala japonica,and has been reported to protect cells against apoptosis.To investigate the mechanisms underlying the neuroprotective effects of PGSF against glutamateinduced cytotoxicity,PGSF-pretreated hippocampal neurons were exposed to glutamate for 24 hours.The results demonstrated that PGSF inhibited glutamate-induced hippocampal neuron death in a concentration-dependent manner and reduced glutamate-induced Ca^(2+)overload in the cultured neurons.In addition,PGSF partially blocked the excess activity of NMDARs,inhibited both the downregulation of NMDAR subunit NR2A expression and the upregulation of NMDAR subunit NR2B expression,and upregulated the expression of phosphorylated cyclic adenosine monophosphate-responsive element-binding protein and brain-derived neurotrophic factor.These findings suggest that PGSF protects cultured hippocampal neurons against glutamate-induced cytotoxicity by regulating NMDARs.The study was approved by the Institutional Animal Care Committee of Nanchang University(approval No.2017-0006)on December 29,2017.
基金the Natural Science Foundation of Jiangsu Province, No. BK2004048the Social Development and Technology Plan of Nantong City, No. K2008009
文摘BACKGROUND: Nerve growth factor (NGF) attenuates glutamate-induced injury to hippocampal neurons, and the human tumor suppressor gene phosphatase and tensin homologue deleted on chromosome 10 (PTEN) promotes neuronal apoptosis. However, effects of PTEN in NGF-mediated neuroprotection against glutamate excitotoxicity remain poorly understood. OBJECTIVE: To investigate the relationship between NGF inhibition of glutamate-induced injury and PTEN. DESIGN, TIME AND SE'I'rlNG: The randomized, controlled, in vitro study was performed at the Department of Pathophysiology, Medical School of Nantong University, China from October 2007 to March 2008. MATERIALS: Glutamate, NGF, 4, 6-diamidino-2-phenyl-indolediacetate, 3-[4, 5-dimethylthiazol-2-yl]- 2, 5-diphenyl tetrazoliumbromide (M-I-F), and lactate dehydrogenase kit (Sigma, USA), fluorescence microscope and inverted phase contrast microscope (Olympus, Japan) were used in this study. METHODS: Hippocampal neurons were obtained from newborn (〈 24 hours) Sprague Dawley rats and cultured for 7 days. The control group was not treated with any intervention factor, the glutamate group was treated with glutamate (0.2 mmol/L), and NGF groups were treated with NGF (10, 50, 100, and 200 μg/L, respectively) prior to glutamate treatment. MAIN OUTCOME MEASURES: The MTT and lactate dehydrogenase assays were applied to evaluate viability of hippocampal neurons. Morphological changes in hippocampal neurons were observed using an inverted phase-contrast microscope, and neuronal apoptosis was detected by 4, 6-diamidino-2- phenyl-indolediacetate staining. PTEN mRNA and protein expression were measured by reverse transcription-polymerase chain reaction and Western blot analysis, respectively. RESULTS: Glutamate (0.2 mmol/L) induced significantly decreased neuronal viability and greater lactate dehydrogenase efflux compared with the control group (P 〈 0.01). However, compared with the glutamate group, cell viability significantly increased and lactate dehydrogenase efflux decreased in the NGF group with increasing NGF concentrations (P 〈 0.05 or P 〈 0.01). The apoptotic ratio and PTEN mRNA and protein expression decreased in the NGF group compared with the glutamate group (P 〈 0.01). CONCLUSION: Pretreatment with NGF exerted neuroprotective effects against glutamate-induced injury, partially through inhibition of PTEN expression and neuronal apoptosis.
基金supported by University of Florence RICATEN 2023 to EC.Grant/Award Numbers 58514_InternazionalizzazioneUniversity of Florence,to EC.Parkinson’s UK,Grant/Award Number:H-0902 to AJGWellcome Trust,Grant/Award Number:0926/Z/10/Z to AJG。
文摘During brain ischemia,excitotoxicity and peri-infarct depolarization injuries occur and cause cerebral tissue damage.Indeed,anoxic depolarization,consisting of massive neuronal depolarization due to the loss of membrane ion gradients,occurs in vivo or in vitro during an energy failure.The neuromodulator adenosine is released in huge amounts during cerebral ischemia and exerts its effects by activating specific metabotropic receptors,namely:A_(1),A_(2A),A_(2B),and A_(3).The A_(2A)receptor subtype is highly expressed in striatal medium spiny neurons,which are particularly susceptible to ischemic damage.Evidence indicates that the A2Areceptors are upregulated in the rat striatum after stroke and the selective antagonist SCH58261 protects from exaggerated glutamate release within the first 4 hours from the insult and alleviates neurological impairment and histological injury in the following 24 hours.We recently added new knowledge to the mechanisms by which the adenosine A2Areceptor subtype participates in ischemia-induced neuronal death by performing patch-clamp recordings from medium spiny neurons in rat striatal brain slices exposed to oxygen and glucose deprivation.We demonstrated that the selective block of A2Areceptors by SCH58261 significantly reduced ionic imbalance and delayed the anoxic depolarization in medium spiny neurons during oxygen and glucose deprivation and that the mechanism involves voltage-gated K+channel modulation and a presynaptic inhibition of glutamate release by the A2Areceptor antagonist.The present review summarizes the latest findings in the literature about the possibility of developing selective ligands of A2Areceptors as advantageous therapeutic tools that may contribute to counteracting neurodegeneration after brain ischemia.
基金supported by the National Natural Science Foundation of China,Nos.81672171(to XY),81620108018(to SQF),81772342(to GZN)the State Key Laboratory of Medicinal Chemical Biology of Nankai University of China,No.2017027(to XY)
文摘The iron chelator deferoxamine has been shown to inhibit ferroptosis in spinal cord injury.However,it is unclear whether deferoxamine directly protects neurons from ferroptotic cell death.By comparing the survival rate and morphology of primary neurons and SH-SY5Y cells exposed to erastin,it was found that these cell types respond differentially to the duration and concentration of erastin treatment.Therefore,we studied the mechanisms of ferroptosis using primary cortical neurons from E16 mouse embryos.After treatment with 50μM erastin for 48 hours,reactive oxygen species levels increased,and the expression of the cystine/glutamate antiporter system light chain and glutathione peroxidase 4 decreased.Pretreatment with deferoxamine for 12 hours inhibited these changes,reduced cell death,and ameliorated cellular morphology.Pretreatment with the apoptosis inhibitor Z-DEVD-FMK or the necroptosis inhibitor necrostain-1 for 12 hours did not protect against erastin-induced ferroptosis.Only deferoxamine protected the primary cortical neurons from ferroptosis induced by erastin,confirming the specificity of the in vitro ferroptosis model.This study was approved by the Animal Ethics Committee at the Institute of Radiation Medicine of the Chinese Academy of Medical Sciences,China(approval No.DWLL-20180913)on September 13,2018.
基金supported by the Ministry of Education,Science and Technological Development of Republic of Serbia,Nos.451-03-68/2022-14/200007 and 451-03-68/2022-14/200053(to LN and JBP),Grants from European Commission(H2020 MSCA-ITN EU-GliaPhD No.72205)(to PN)Agence Nationale de la Recherche,Nos.ANR-19-CE16-0018-03 and ANR-20CE16-0003-02(to PN)+1 种基金Grants from Science and Technology Department of Zhejiang Province,China,No.2021RC051(to WS)Scientific Research Foundation for Returned Scholars of Hangzhou City,China,No.2019(to WS).
文摘Epilepsy is a neurological disorder caused by the pathological hyper-synchronization of neuronal discharges.The fundamental research of epilepsy mechanisms and the targets of drug design options for its treatment have focused on neurons.However,approximately 30%of patients suffering from epilepsy show resistance to standard anti-epileptic chemotherapeutic agents while the symptoms of the remaining 70%of patients can be alleviated but not completely removed by the current medications.Thus,new strategies for the treatment of epilepsy are in urgent demand.Over the past decades,with the increase in knowledge on the role of glia in the genesis and development of epilepsy,glial cells are receiving renewed attention.In a normal brain,glial cells maintain neuronal health and in partnership with neurons regulate virtually every aspect of brain function.In epilepsy,however,the supportive roles of glial cells are compromised,and their interaction with neurons is altered,which disrupts brain function.In this review,we will focus on the role of glia-related processes in epileptogenesis and their contribution to abnormal neuronal activity,with the major focus on the dysfunction of astroglial potassium channels,water channels,gap junctions,glutamate transporters,purinergic signaling,synaptogenesis,on the roles of microglial inflammatory cytokines,microglia-astrocyte interactions in epilepsy,and on the oligodendroglial potassium channels and myelin abnormalities in the epileptic brain.These recent findings suggest that glia should be considered as the promising next-generation targets for designing anti-epileptic drugs that may improve epilepsy and drug-resistant epilepsy.
文摘In this study,I focused on finding a mean of protecting against hearing loss.By infusing the cochlea with the neurotrophin factor,NT-3 alone or combined treatment with MK 801,a NMDA receptor antagonist I found hearing loss was attenuated and spiral ganglion neuron loss was nearly totally protected indicating that the importance of the combined treatment of NT-3 and NMDA receptor antagonists in the treatment of hearing disorders.
基金supported by the National Natural Science Foundation of China,No.81371967 and 81401807a grant from the 5th Phase of "Project 333"of Jiangsu Province of China,No.BRA2016512a grant from the Six Talent Peaks Project of Jiangsu Province of China,No.2014-WSN-012
文摘Mitochondrial division inhibitor 1(Mdivi-1) is a selective cell-permeable inhibitor of dynamin-related protein-1(Drp1) and mitochondrial division.To investigate the effect of Mdivi-1 on cells treated with glutamate,cerebral cortex neurons isolated from neonatal rats were treated with 10 m M glutamate for 24 hours.Normal cultured cells and dimethyl sulfoxide-cultured cells were considered as controls.Apoptotic cells were detected by flow cytometry.Changes in mitochondrial morphology were examined by electron microscopy.Drp1,Bax,and casp ase-3 expression was evaluated by western blot assays and immunocytochemistry.Mitochondrial membrane potential was detected using the JC-1 probe.Twenty-four hours after 10 m M glutamate treatment,Drp1,Bax and caspase-3 expression was upregulated,Drp1 and Bax were translocated to mitochondria,mitochondrial membrane potential was decreased and the rate of apoptosis was increased.These effects were inhibited by treatment with 50 μM Mdivi-1 for 2 hours.This finding indicates that Mdivi-1 is a candidate neuroprotective drug that can potentially mitigate against neuronal injury caused by glutamate-induced excitotoxicity.
文摘Glial glutamate transporter-1(GLT-1)is the predominant subtype of glutamate transporters and is responsible for the clearance of extracellular glutamate and for limiting the concentration of extracellular glutamate.Our previous studies have shown that the up-regulation of GLT-1 expression plays an important role
基金This work was supported by the Chinese Academy of Preventive Medicine Fund.
文摘Objective To examine the effects of Pb2+ on N-methyl-D-aspartate (NMDA)-, K+- and quisqualate(QA)/kainite(KA)-induced increases in intracellular free calcium concentration ([Ca2+],) in cultured fetal rat hippocampal neurons in order to explain the cognitive and learning deficits produced by this heavy metal. Methods Laser scanning confocal microscopy was used. Results The results clearly demonstrated that adding Pb2+ before or after NMDA/glycine stimulation selectively inhibited the stimulated increases in [Ca2+], in a concentration-dependent manner. In contrast, Pb2+ treatment did not markedly affect increases in [Ca2+], induced by an admixture of QA and KA. The minimal inhibitory effect of Pb2+ occurred at 1 μmol/L, and more than seventy percent abolition of the NMDA-stimulated increase in [Ca2+]; was observed at 100 Jμmoll/L Pb2+. Evaluation of Pb2+-induced increase in [Ca2+], response to elevating extracellular concentrations of NMDA, glycine or calcium revealed that Pb2+ was a noncompetitive antagonist of both NMDA and glycine, and a competitive antagonist of Ca2+ at NMDA receptor channels. In addition. Pb2+ inhibited depolarization-evoked increases in [Ca2+], mediated by K+ stimulation(30μmol/L). indicating that Pb2+ also depressed the voltage-dependent calcium channels. Also, the results showed that Pb2+ appeared to be able to elevate the resting levels of [Ca2+|, in cultured neurons, implying a reason for Pb2+-enhanced spontaneous release of several neurotransmitters reported in several previous studies. Conclusion Lead can inhibit NMDA-. K+-, QA/KA-jnduced increases in intracellular [Ca2+], in cultured hippocampal neurons.
基金the Key Project of Technology of Ministry of Education, No. 2007029
文摘Gentianine has been shown to have a protective effect on hippocampal CA1 neurons in rats subjected to recurrent febrile convulsion(FC).The present study sought to explore the possible mechanism of gentianine by intraperitoneally injecting gentianine into rats with warm water-induced FC.The results revealed that neuronal organelle injury was slightly ameliorated in the hippocampal CA1 region.The level of glutamate was decreased,but the level of γ-aminobutyric acid was increased,as detected by ninhydrin staining.In addition,glutamate acid decarboxylase expression in hippocampal CA1 was increased,as determined by immunohistochemistry.The results demonstrated that gentianine can ameliorate FC-induced neuronal injury by enhancing glutamate acid decarboxylase activity,decreasing glutamate levels and increasing γ-aminobutyric acid levels.
基金supported by the National Natural Science Foundation of China, No. 30930093the Natural Science Foundation of Shaanxi Province, No. 2005C_245
文摘Activation of metabotropic glutamate receptor la aggravates traumatic brain injury. The constitutively expressed protein Homerlb/c participates in delivering and anchoring metabotropic glutamate receptors in neurons. Here, we aimed to verify whether down-regulation of Homerlb/c by RNA interference could protect cultured rat cortical neurons from traumatic injury. We showed that 36 hours after transfection of Homerlb/c small interfering RNA, metabotropic glutamate receptor la was present only in the neuronal cytoplasm, but not in the dendrites. Calcium fluorescence intensity was also decreased significantly. Moreover, lactate dehydrogenase concentration was significantly decreased in Homerlb/c small interfering RNA-transfected cells compared with that in untransfected and control small interfering RNA-transfected cells 24 hours after traumatic neuronal injury. Our findings indicate that down-regulation of Homerlb/c could reduce metabotropic glutamate receptor la transfer from the cell body to the dendrite, relieve calcium overload, and protect neurons from traumatic injury.
文摘Glutamate(Glu)is the main excitatory amino acid in the brain and plays a pivotal role in many neurophysiological functions.Nevertheless,an excess and prolonged exposure to Glu determines the overactivation of glutamate receptors(Glu Rs)with consequent impairment of cellular calcium(Ca2+)homeostasis,
基金supported by the National Natural Science Foundation of China,No.30972441,81202158
文摘The present study used cultures of primary astrocytes, isolated from neonatal rats, to verify the hypothesis that arsenite-induced neurotoxicity can influence neuronal function by altering glutamate-induced gliotransmitter release. Primary astrocytes were exposed to 0, 2.5, 5, 10, 20 or 30 μM arsenite for 24 hours. Cell viability and morphological observations revealed that 5 μM arsenic exposure could induce cytotoxicity. Cells were then cultured in the presence of 0, 2.5, 5, or 10 μM arsenite for 24 hours and stimulated with 25 μM glutamate for 10 minutes. Results showed that [Ca2+]i in astrocytes exposed to 5 and 10 μM arsenite was significantly increased and levels of D-serine, γ-aminobutyric acid and glycine in cultures exposed to 2.5-10 μM arsenite were also increased. However, glutamate levels in the media were significantly increased only after treatment with 10 μM arsenite. In conclusion, our findings suggest that arsenic exposure may affect glutamate-induced gliotransmitter release from astrocytes and further disturb neuronal function.
文摘Increasing evidence, including from our laboratory, has revealed that opening of ATP sensitive potassium channels(K-ATP channels) plays the neuronal protective roles both in vivo and in vitro. Thus K-ATP channel openers(KCOs) have been proposed as potential neuroprotectants. Our previous studies demonstrated that K-ATP channels could regulate glutamate uptake activity in PC12 cells as well as in synaptosomes of rats. Since glutamate transporters(GluTs) of astrocytes play crucial roles in glutamate uptake and KATP channels are also expressed in astrocytes, the present study showed whether and how KATP channels regulated the function of GluTs in primary cultured astrocytes. The results showed that nonselective KCO pinacidil, selective mitochondrial KCO diazoxide, novel, and blood-brain barrier permeable KCO iptakalim could enhance glutamate uptake, except for the sarcolemmal KCO P1075. Moreover pinacidil, diazoxide, and iptakalim reversed the inhibition of glutamate uptake induced by 1-methyl-4-phenylpyridinium(MPP+). These potentiated effects were completely abolished by mitochondrial K-ATP blocker 5-hydroxydecanoate. Furthermore, either diazoxide or iptakalim could inhibit MPP+-induced elevation of reactive oxygen species (ROS) and phosphorylation of protein kinases C(PKC). These findings are the first to demonstrate that activation of K-ATP channel, especially mitochondrial K-ATP channel, improves the function of GluTs in astrocytes due to reducing ROS production and downregulating PKC phosphorylation. Therefore, the present study not only reveals a novel pharmacological profile of KCOs as regulators of GluTs, but also provides a new strategy for neuroprotection.
文摘To investigate the expression of interleukin 2 (IL 2), metabotropic glutamate receptor subunit 1 (mGluR1) and estrogen receptor (ER) in neurons of the rat central nervous system (CNS) and identify the coexistence possibility of these immune neuro endocrine substances in the central neurons, the tri labeling immunocytochemical technique with different species specific primary antibodies (goat anti IL 2 antibody, rabbit anti mGluR1 antibody and mouse anti ER antibody ) were used to incubate two serial neighbor sections (one for demonstrating IL 2, another for mGluR1 and ER) of the cerebral cortex, medulla oblongata and spinal cord. There were IL 2 , mGluR1 and ER immunoreactivity (IR) positive labeled neurons in the above mentioned central areas. The IL 2 IR production showed brown color, located in the cytoplasm; In the neighbor serial section, the mGluR1 IR, production showed blue black color, located on the cell membrane; the ER IR production also showed brown color, located in the cytoplasm and nuclei. There were mGluR1/ER double labeled cells in the same section, which accounted for about 50 %-60 % of the total single and double labeled neurons. It was identified by projection check of serial neighbor sections that had mGluR1/ER/IL 2 tri labeled cells, which accounted for about 30 % of total mGluR1/ER double labeled neurons. The results indicate that mGluR1, ER and Il 2 can coexist in the same rat central neurons, therefore, providing morphological basis for the theory about immune neuro endocrine network at the cellular level for the first time.