scholarly journals Yokukansan, a Traditional Japanese Medicine, Enhances the Glutamate Transporter GLT-1 Function in Cultured Rat Cortical Astrocytes

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Toshiyuki Ueki ◽  
Zenji Kawakami ◽  
Hitomi Kanno ◽  
Yuji Omiya ◽  
Kazushige Mizoguchi ◽  
...  
Keyword(s):  
Glutamate Uptake ◽  
Glutamate Transporter ◽  
Culture Conditions ◽  
Mrna Levels ◽  
Extracellular Glutamate ◽  
Cultured Astrocytes ◽  
Traditional Japanese Medicine ◽  
Uptake Activity ◽  
The Brain ◽  
Necrosis Factor

Astrocytes carry two glutamate transporters—GLAST and GLT-1—the latter of which is responsible for >90% of glutamate uptake activity in the brain; however, under culture conditions, the GLT-1 expression in astrocytes is exceedingly low, as is the glutamate uptake activity mediated by GLT-1. This study aimed to elucidate the effects of yokukansan (YKS) in relation to the GLT-1-mediated regulation of extracellular glutamate concentrations. Thus, we treated cultured astrocytes with tumor necrosis factor-α (TNF-α) and dibutyryl-cAMP (dBcAMP) (hereinafter, referred to as “TA”) to increase GLT-1 expression and then functionally examined how YKS would affect glutamate uptake ability derived from GLT-1. Contrary to expectations, although the TA treatments did not affect the uptake activity, YKS significantly augmented it. Conversely, GLAST-derived glutamate uptake was significantly reduced by TA treatments but was unaffected by YKS. Subsequently, we analyzed the GLT-1 protein and mRNA levels and found that TA treatments had significantly increased them, which were then further augmented by YKS. These findings suggest that YKS enhances GLT-1-derived glutamate transport functions in TA-treated cultured astrocytes and that this process entails increased GLT-1 protein and mRNA levels. This type of mechanism may contribute to the YKS-mediated regulation of extracellular glutamate concentrations.

scholarly journals GLT-1 overexpression attenuates bladder nociception and local/cross-organ sensitization of bladder nociception

2011 ◽  
Vol 300 (6) ◽  
pp. F1353-F1359 ◽  
Author(s):  
M. Yang ◽  
K. Roman ◽  
D.-F. Chen ◽  
Z.-G. Wang ◽  
Y. Lin ◽  
...  
Keyword(s):  
Glutamate Uptake ◽  
Glutamate Transporter ◽  
Vehicle Group ◽  
Trinitrobenzene Sulfonic Acid ◽  
Nociceptive Response ◽  
Bladder Distension ◽  
Beneficial Effects ◽  
Visceromotor Response ◽  
Colonic Distension ◽  
Uptake Activity

Glutamatergic pathways mediate transmission of pain. Strategies to reduce glutamatergic neurotransmission may have beneficial effects to mitigate nociception. Recent work revealed that overexpression of the astrocytic glutamate transporter (GLT-1) by transgenic or pharmacologic approaches produced a diminished visceral nociceptive response to colonic distension. The purpose of this study was to determine the effect of GLT-1 overexpression on the visceromotor response to bladder distension. Increased glutamate uptake activity produced by 1-wk ceftriaxone (CTX) treatment attenuated 60–64% the visceromotor response to graded bladder distension compared with vehicle-treated mice. One-hour pretreatment with selective GLT-1 antagonist dihydrokainate reversed the blunted visceromotor response to bladder distension produced by 1-wk CTX, suggesting that GLT-1 overexpression mediated the analgesic effect of CTX. Moreover, sensitization of the visceromotor response to bladder distension produced by local bladder irritation (acrolein) was also attenuated by 1-wk CTX treatment. A model of cross-organ sensitization of bladder visceromotor response to distension was next studied to determine whether increased expression of GLT-1 can mitigate colon to bladder sensitization. Intracolonic trinitrobenzene sulfonic acid (TNBS) administered 1 h before eliciting the visceromotor response to graded bladder distension produced a 75–138% increase in visceromotor response compared with animals receiving intracolonic vehicle. In marked contrast, animals treated with 1-wk CTX + intracolonic TNBS showed no enhanced visceromotor response compared with the 1-wk vehicle + intracolonic vehicle group. The study suggests that GLT-1 overexpression attenuates the visceromotor response to bladder distension and both local irritant-induced and cross-organ-sensitized visceromotor response to bladder distension.

scholarly journals Ischemic Preconditioning Reveals that GLT1/EAAT2 Glutamate Transporter is a Novel PPARγ Target Gene Involved in Neuroprotection

2007 ◽  
Vol 27 (7) ◽  
pp. 1327-1338 ◽  
Author(s):  
Cristina Romera ◽  
Olivia Hurtado ◽  
Judith Mallolas ◽  
Marta P Pereira ◽  
Jesús R Morales ◽  
...  
Keyword(s):  
Nervous System ◽  
Ischemic Preconditioning ◽  
Transcriptional Activity ◽  
Target Gene ◽  
Glutamate Uptake ◽  
Glutamate Release ◽  
Glutamate Transporter ◽  
Glutamate Transport ◽  
Extracellular Glutamate ◽  
Pparγ Agonist

Excessive levels of extracellular glutamate in the nervous system are excitotoxic and lead to neuronal death. Glutamate transport, mainly by glutamate transporter GLT1/EAAT2, is the only mechanism for maintaining extracellular glutamate concentrations below excitotoxic levels in the central nervous system. We recently showed that neuroprotection after experimental ischemic preconditioning (IPC) involves, at least partly, the upregulation of the GLT1/EAAT2 glutamate transporter in astrocytes, but the mechanisms were unknown. Thus, we decided to explore whether activation of the nuclear receptor peroxisome proliferator-activated receptor (PPAR)γ, known for its antidiabetic and antiinflammatory properties, is involved in glutamate transport. First, we found that the PPARγ antagonist T0070907 inhibits both IPC-induced tolerance and reduction of glutamate release after lethal oxygen-glucose deprivation (OGD) (70.1% ± 3.4% versus 97.7% ± 5.2% of OGD-induced lactate dehydrogenase (LDH) release and 61.8% ± 5.9% versus 85.9% ± 7.9% of OGD-induced glutamate release in IPC and IPC + T0070907 1 μmol/L, respectively, n = 6 to 12, P < 0.05), as well as IPC-induced astrocytic GLT-1 overexpression. IPC also caused an increase in nuclear PPARγ transcriptional activity in neurons and astrocytes (122.1% ± 8.1% and 158.6% ± 22.6% of control PPARγ transcriptional activity, n = 6, P < 0.05). Second, the PPARγ agonist rosiglitazone increased both GLT-1/EAAT2 mRNA and protein expression and [3H]glutamate uptake, and reduced OGD-induced cell death and glutamate release (76.3% ± 7.9% and 65.5% ± 15.1% of OGD-induced LDH and glutamate release in rosiglitazone 1 μmol/l, respectively, n = 6 to 12, P < 0.05). Finally, we have identified six putative PPAR response elements (PPREs) in the GLT1/EAAT2 promoter and, consistently, rosiglitazone increased fourfold GLT1/EAAT2 promoter activity. All these data show that the GLT1/EAAT2 glutamate transporter is a target gene of PPARγ leading to neuroprotection by increasing glutamate uptake.

scholarly journals The Meningococcal ABC-Type l-Glutamate Transporter GltT Is Necessary for the Development of Experimental Meningitis in Mice

2009 ◽  
Vol 77 (9) ◽  
pp. 3578-3587 ◽  
Author(s):  
Roberta Colicchio ◽  
Susanna Ricci ◽  
Florentia Lamberti ◽  
Caterina Pagliarulo ◽  
Chiara Pagliuca ◽  
...  
Keyword(s):  
Histological Analysis ◽  
Glutamate Uptake ◽  
Glutamate Transporter ◽  
Systemic Infection ◽  
Fold Increase ◽  
Wild Type ◽  
Nutrient Source ◽  
Infectious Dose ◽  
Life Threatening ◽  
The Brain

ABSTRACT Experimental animal models of bacterial meningitis are useful to study the host-pathogen interactions occurring at the cerebral level and to analyze the pathogenetic mechanisms behind this life-threatening disease. In this study, we have developed a mouse model of meningococcal meningitis based on the intracisternal inoculation of bacteria. Experiments were performed with mouse-passaged serogroup C Neisseria meningitidis. Survival and clinical parameters of infected mice and microbiological and histological analysis of the brain demonstrated the establishment of meningitis with features comparable to those of the disease in humans. When using low bacterial inocula, meningococcal replication in the brain was very efficient, with a 1,000-fold increase of viable counts in 18 h. Meningococci were also found in the blood, spleens, and livers of infected mice, and bacterial loads in different organs were dependent on the infectious dose. As glutamate uptake from the host has been implicated in meningococcal virulence, mice were infected intracisternally with an isogenic strain deficient in the ABC-type l-glutamate transporter GltT. Noticeably, the mutant was attenuated in virulence in mixed infections, indicating that wild-type bacteria outcompeted the GltT-deficient meningococci. The data show that the GltT transporter plays a role in meningitis and concomitant systemic infection, suggesting that meningococci may use l-glutamate as a nutrient source and as a precursor to synthesize the antioxidant glutathione.

scholarly journals Lesion-Induced Alterations in Astrocyte Glutamate Transporter Expression and Function in the Hippocampus

2013 ◽  
Vol 2013 ◽  
pp. 1-16 ◽  
Author(s):  
Alexandra E. Schreiner ◽  
Eric Berlinger ◽  
Julia Langer ◽  
Karl W. Kafitz ◽  
Christine R. Rose
Keyword(s):  
Cell Damage ◽  
Glutamate Uptake ◽  
Hippocampal Slices ◽  
Glutamate Transporter ◽  
Reactive Astrocytes ◽  
Extracellular Glutamate ◽  
Sodium Imaging ◽  
Ca1 Area ◽  
And Function ◽  
Transporter Expression

Astrocytes express the sodium-dependent glutamate transporters GLAST and GLT-1, which are critical to maintain low extracellular glutamate concentrations. Here, we analyzed changes in their expression and function following a mechanical lesion in the CA1 area of organotypic hippocampal slices. 6-7 days after lesion, a glial scar had formed along the injury site, containing strongly activated astrocytes with increased GFAP and S100β immunoreactivity, enlarged somata, and reduced capability for uptake of SR101. Astrocytes in the scar’s periphery were swollen as well, but showed only moderate upregulation of GFAP and S100β and efficiently took up SR101. In the scar, clusters of GLT-1 and GLAST immunoreactivity colocalized with GFAP-positive fibers. Apart from these, GLT-1 immunoreactivity declined with increasing distance from the scar, whereas GLAST expression appeared largely uniform. Sodium imaging in reactive astrocytes indicated that glutamate uptake was strongly reduced in the scar but maintained in the periphery. Our results thus show that moderately reactive astrocytes in the lesion periphery maintain overall glutamate transporter expression and function. Strongly reactive astrocytes in the scar, however, display clusters of GLAST and GLT-1 immunoreactivity together with reduced glutamate transport activity. This reduction might contribute to increased extracellular glutamate concentrations and promote excitotoxic cell damage at the lesion site.

Effects of SSRI on L-glutamate uptake activity of cultured astrocytes

2009 ◽  
Vol 65 ◽  
pp. S87
Author(s):  
Junpei Takaki ◽  
Jun-Ichi Kuriwaki ◽  
Kaoru Sato ◽  
Takeshi Suzuki
Keyword(s):  
Glutamate Uptake ◽  
Cultured Astrocytes ◽  
Uptake Activity

Deep Hypothermia and Rewarming Alters Glutamate Levels and Glycogen Content in Cultured Astrocytes 

1999 ◽  
Vol 91 (6) ◽  
pp. 1763-1763 ◽  
Author(s):  
Bruno Bissonnette ◽  
Luc Pellerin ◽  
Patrick Ravussin ◽  
Véronique B. Daven ◽  
Pierre J. Magistretti
Keyword(s):  
Glycogen Content ◽  
Glutamate Uptake ◽  
Primary Cultures ◽  
Deep Hypothermia ◽  
Extracellular Glutamate ◽  
Mild Hyperthermia ◽  
Extracellular Concentration ◽  
Sequence Of Events ◽  
Cultured Astrocytes

Background Deep hypothermia has been associated with an increased incidence of postoperative neurologic dysfunction after cardiac surgery in children. Recent studies suggest an excitotoxic mechanism involving overstimulation of glutamate receptors. Extracellular glutamate uptake occurs primarily by astrocytes. Astrocytes also store glycogen, which may be used to sustain the energy-consuming glutamate uptake. Extracellular glutamate and glycogen content were studied during temperature changes mimicking cardiopulmonary bypass in vivo. Methods Primary cultures of cerebral cortical astrocytes were used in a specially designed incubator allowing continuous changes of temperature and ambient gas concentrations. The sequence of events was as follows: normothermia, rapid cooling (2.8 degrees C/min) followed by 60 min of deep hypothermia (15 degrees C), followed by rewarming (3.0 degrees C/min) and subsequent 5 h of mild hyperthermia (38.5 degrees C). Two different conditions of oxygenation were studied: (1) normoxia (25% O2, 70% N2, 5% CO2); or (2) hyperoxia (95% O2, 5% CO2). The extracellular glutamate concentrations and intracellular glycogen levels were measured at nine time points. Results One hundred sixty-two cultures were studied in four independent experiments. The extracellular concentration of glutamate in the normoxic group increased significantly from 35+/-10 nM/mg protein at baseline up to 100+/-15 nM/mg protein at the end of 5 h of mild hyperthermia (P &lt; 0.05). In contrast, extracellular glutamate levels did not vary from control in the hyperoxic group. Glycogen levels decreased significantly from 260+/-85 nM/mg protein at baseline to &lt; 25+/-5 nM/mg protein at the end of 5 h in the normoxic group (P &lt; 0.05) but returned to control levels after rewarming in the hyperoxic group. No morphologic changes were observed in either group. Conclusion The extracellular concentration of glutamate increases, whereas the intracellular glycogen content decreases when astrocytes are exposed to a sequence of deep hypothermia and rewarming. This effect of hypothermia is prevented when astrocytes are exposed to hyperoxic conditions.

scholarly journals Effect of Inhibition of Spinal Cord Glutamate Transporters on Inflammatory Pain Induced by Formalin and Complete Freund's Adjuvant

2011 ◽  
Vol 114 (2) ◽  
pp. 412-423 ◽  
Author(s):  
Myron Yaster ◽  
Xiaowei Guan ◽  
Ronald S. Petralia ◽  
Jeffery D. Rothstein ◽  
Wei Lu ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Dorsal Horn ◽  
Inflammatory Pain ◽  
Glutamate Uptake ◽  
Glutamate Transporter ◽  
Glutamate Transporters ◽  
Superficial Dorsal Horn ◽  
Group Iii ◽  
Metabotropic Glutamate ◽  
Uptake Activity

Background Spinal cord glutamate transporters clear synaptically released glutamate and maintain normal sensory transmission. However, their ultrastructural localization is unknown. Moreover, whether and how they participate in inflammatory pain has not been carefully studied. Methods Immunogold labeling with electron microscopy was carried out to characterize synaptic and nonsynaptic localization of glutamate transporters in the superficial dorsal horn. Their expression and uptake activity after formalin- and complete Freund's adjuvant (CFA)-induced inflammation were evaluated by Western blot analysis and glutamate uptake assay. Effects of intrathecal glutamate transporter activator (R)-(-)-5-methyl-1-nicotinoyl-2-pyrazoline and inhibitors (DL-threo-β-benzyloxyaspartate [TBOA], dihydrokainate, and DL-threo-β-hydroxyaspartate), or TBOA plus group III metabotropic glutamate receptor antagonist (RS)-α-methylserine-O-phosphate, on formalin- and CFA-induced inflammatory pain were examined. Results In the superficial dorsal horn, excitatory amino acid carrier 1 is localized in presynaptic membrane, postsynaptic membrane, and axonal and dendritic membranes at nonsynaptic sites, whereas glutamate transporter-1 and glutamate/aspartate transporter are prominent in glial membranes. Although expression of these three spinal glutamate transporters was not altered 1 h after formalin injection or 6 h after CFA injection, glutamate uptake activity was decreased at these time points. Intrathecal (R)-(-)-5-methyl-1-nicotinoyl-2-pyrazoline had no effect on formalin-induced pain behaviors. In contrast, intrathecal TBOA, dihydrokainate, and DL-threo-β-hydroxyaspartate reduced formalin-evoked pain behaviors in the second phase. Intrathecal TBOA also attenuated CFA-induced thermal hyperalgesia at 6 h after CFA injection. The antinociceptive effects of TBOA were blocked by coadministration of (RS)-α-methylserine-O-phosphate. Conclusion Our findings suggest that spinal glutamate transporter inhibition relieves inflammatory pain through activation of inhibitory presynaptic group III metabotropic glutamate receptors.

scholarly journals PKN1 promotes synapse maturation by inhibiting mGluR-dependent silencing through neuronal glutamate transporter activation

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Hiroki Yasuda ◽  
Hikaru Yamamoto ◽  
Kenji Hanamura ◽  
Mona Mehruba ◽  
Toshio Kawamata ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Metabotropic Glutamate Receptor ◽  
Excitatory Amino Acid ◽  
Glutamate Uptake ◽  
Critical Role ◽  
Glutamate Transporter ◽  
Wild Type ◽  
Excitatory Amino Acid Transporter ◽  
The Brain ◽  
Neuronal Glutamate Transporter

AbstractAbnormal metabotropic glutamate receptor (mGluR) activity could cause brain disorders; however, its regulation has not yet been fully understood. Here, we report that protein kinase N1 (PKN1), a protein kinase expressed predominantly in neurons in the brain, normalizes group 1 mGluR function by upregulating a neuronal glutamate transporter, excitatory amino acid transporter 3 (EAAT3), and supports silent synapse activation. Knocking out PKN1a, the dominant PKN1 subtype in the brain, unmasked abnormal input-nonspecific mGluR-dependent long-term depression (mGluR-LTD) and AMPA receptor (AMPAR) silencing in the developing hippocampus. mGluR-LTD was mimicked by inhibiting glutamate transporters in wild-type mice. Knocking out PKN1a decreased hippocampal EAAT3 expression and PKN1 inhibition reduced glutamate uptake through EAAT3. Also, synaptic transmission was immature; there were more silent synapses and fewer spines with shorter postsynaptic densities in PKN1a knockout mice than in wild-type mice. Thus, PKN1 plays a critical role in regulation of synaptic maturation by upregulating EAAT3 expression.

scholarly journals Endothelin-1 decreases glutamate uptake in primary cultured rat astrocytes

2001 ◽  
Vol 281 (5) ◽  
pp. C1495-C1503 ◽  
Author(s):  
Julia Leonova ◽  
Thorleif Thorlin ◽  
N. David Åberg ◽  
Peter S. Eriksson ◽  
Lars Rönnbäck ◽  
...  
Keyword(s):  
Glutamate Uptake ◽  
Wide Spectrum ◽  
Glutamate Transporter ◽  
Fatty Acid Binding ◽  
Endothelin 1 ◽  
Biological Responses ◽  
Cultured Astrocytes ◽  
Intracellular Ca ◽  
Potent Vasoconstrictor ◽  
Glutamate Transporter 1

Endothelin-1 (ET-1) is a potent vasoconstrictor peptide that is also known to induce a wide spectrum of biological responses in nonvascular tissue. In this study, we found that ET-1 (100 nM) inhibited the glutamate uptake in cultured astrocytes expressing the glutamate/aspartate transporter (GLAST); astrocytes did not express the glutamate transporter-1 (GLT-1). The V maxand the K m of the glutamate uptake were reduced by 57% and 47%, respectively. Application of the ETA and ETB receptor antagonists BQ-123 and BQ-788 partly inhibited the ET-1-evoked decrease in the glutamate uptake, whereas the nonspecific ET receptor antagonist bosentan completely inhibited this decrease. Incubation of the cultures with pertussis toxin abolished the effect of ET-1 on the uptake. The ET-1-induced decrease in the glutamate uptake was independent of extracellular free Ca2+concentration, whereas the intracellular Ca2+ antagonists thapsigargin and 3,4,5-trimethoxybenzoic acid 8-(diethylamino)octyl ester abolished the effect of ET-1 on the glutamate uptake. Incubation with the protein kinase C (PKC) antagonist staurosporine, but not with the fatty acid-binding protein bovine serum albumin, prevented the ET-1-induced decrease in the glutamate uptake. These results suggest that ET-1 impairs the high-affinity glutamate uptake in cultured astrocytes through a G protein-coupled mechanism, involving PKC and changes in intracellular Ca2+.

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